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Aneurysmal bone cyst of the pelvis: systematic literature review
*Corresponding author: Ayesha Saeed, Department of Pediatric Orthopedics, The Children’s Hospital and The Institute of Child Health, Faisalabad, Pakistan. drayeshasaeed@gmail.com
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Received: ,
Accepted: ,
How to cite this article: Saeed A, Rometsch E, Chong AH. Aneurysmal bone cyst of the pelvis: Systematic literature review. J Musculoskelet Surg Res 2023;7:11-23.
Abstract
Aneurysmal bone cysts (ABCs) are rare benign, vascular, and osteolytic bone lesions. Pelvic ABCs account for 8–12% of these tumors and no clear guidelines for their treatment are available. To the best of our knowledge, this is the first systematic literature review regarding pelvic ABCs. Our objective was to identify treatment modalities and assess bone healing, measured as the degree of radiological ossification. Searches were conducted in PubMed, Cochrane Library, and Web of Science. Based on the scarcity of reports, inclusion criteria were kept broad and included primary or recurrent pelvic ABCs, with a minimum follow-up of 1 year and available information on radiological ossification. Data were extracted at the individual patient level and grouped according to treatment modality. Forty-nine studies reporting on 194 patients were included from the study. The level of evidence was low (29 case reports and 20 retrospective case series), and the reporting of outcomes was inconsistent. Five major treatment groups were identified and divided into 11 subgroups. The largest subgroup was curettage (23%), followed by selective arterial embolization (20%). Most ABCs were located in the ilium. Variations in mean tumor size (4.5–22.2 cm) and degree of ossification (60–100%) depended on the treatment modality. Overall, in 77% of the cases, the cyst ossified completely. Recurrence was reported in 22 patients (11%) and two patients (1%) died during the course of the treatment. This systematic review provides the first comprehensive overview of pelvic ABC treatment modalities and their radiological and clinical outcomes. Neoadjuvant scleroembolic treatments appear to be used most in recent years, but further comparative studies and better quality of reporting are needed to determine their effectiveness.
Keywords
Aneurysmal bone cyst
Benign
Pelvis
Tumor
Selective arterial embolization
INTRODUCTION
Aneurysmal bone cysts (ABCs), also known as “Jaffe-Lichtenstein disease,”[1-3] are rare benign vascular lytic lesions of the bone of unknown etiology.[4,5] The annual incidence of ABC in all bony locations has been reported as 0.14/100,000 people, with slight female preponderance.[6] However, the true incidence is difficult to calculate as some of the ABC cases may have spontaneous regression, and some cases can be clinically silent.[6] Eighty percentages of ABCs occur within the first and second decades of life.[1,7] The clinical course is sometimes unpredictable, and local recurrences are relatively often,[8] with reported recurrence rates from 5% to 40%.[1,9,10]
A study describing the anatomical distribution of 897 ABCs found pelvic lesions in 11.6% of the cases, the fourth most frequent site in descending order after the tibia, femur, and vertebra.[11] In spite of accounting for nearly half of all flat bone lesions,[12] pelvic ABCs are extremely rare. Management of pelvic ABC requires careful consideration of special factors, such as the risk of bleeding, proximity to neurovascular structures, relative inaccessibility, and damage to the integrity of weight-bearing structures such as the acetabulum or sacrum.[8-10]
Several treatment modalities have been reported in the scarce literature available concerning pelvic ABCs.[13] Therefore, we performed a systematic literature review with the primary aim of analyzing the main treatments used for this particular disease and their radiological ossification outcomes. The secondary aims were to describe the demographics, tumor location, clinical and functional outcomes, complications, and recurrence rate.
MATERIALS AND METHODS
A systematic literature review on pelvic ABC was conducted on the September 28, 2017, and reported following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement.[14,15]
Electronic searches were conducted in PubMed, the Cochrane Library, and the Web of Science. The search strategy used a combination of the following terms: ([Pelvis OR pelvic] AND [ABC [MeSH Terms] OR “aneurysmal bone cyst”]). Additional articles were identified by hand, searching the reference lists of relevant articles such as large case series or literature reviews. A first survey of the identified literature revealed that it was limited to retrospective case series and case reports that provided information at the individual patient level in most cases. The eligibility criteria used for this systematic review were as follows:
Inclusion criteria
The following criteria were included in the study:
Primary or recurrent ABC located in the pelvis
Any age
Any treatment method (including observation)
A minimum follow-up of 1 year
Radiological, clinical, and functional outcomes provided by treatment method
Mention of ossification status • English language.
Exclusion criteria
The following criteria were excluded from the study:
Secondary pelvic ABCs
Information on treatment or outcome for pelvic tumors was not specified.
No date limits were applied. Screening and eligibility assessment was performed by the first author. Neither prospective nor comparative studies met the eligibility criteria. Due to the study designs and level of evidence found, data either on individual patients or grouped by treatment were extracted. The articles’ titles, publication year, authors, and number of patients with pelvic ABC were recorded. Articles describing ABCs in multiple locations but containing pelvic zone cases within their study population were also included in the study; only relevant information related to pelvic ABC was used.
Whenever possible, individual patient information on gender, age, location of ABC according to Enneking and Durham anatomic pelvic zones,[16] primary or recurrent ABC, tumor size, Enneking staging,[17] type of treatment, and years of follow-up was recorded.
Rossi et al. described the age groups into four categories, so it was excluded from the calculation of the mean age.[18] According to Enneking and Durham,[16] the pelvic zones used to describe tumor location were: 1 = ilium, 2 = acetabulum, 3 = ischium-pubis, and 4 = sacrum. If a tumor extended over more than one zone, the affected zones were combined into a separate category. Given the different ways of measuring and reporting tumor sizes used in the literature, the mean size was calculated using the maximum dimension reported.
The treatment and the outcomes for pelvic ABCs reported in the studies presented a high degree of heterogeneity. After reviewing the extracted data, treatment modalities were categorized into the following groups and subgroups for the qualitative synthesis of results:
Observation
-
Adjuvant treatment
Selective arterial embolization (SAE)
Sclerotherapy
Radiotherapy
SAE + Sclerotherapy
-
Minor surgery
Curettage
Extended curettage
-
Major surgery
Marginal excision
Wide excision
-
Combined
Adjuvant + minor surgery
Adjuvant + major surgery
The primary outcome was radiological ossification, defined as either “no evidence of disease” or “complete consolidation of the lesion” with or without exogenous material. “Partial ossification” was considered when terms such as “cystic residues,” “partial ossification between 25% and 75%,” or “healed with small and large residual geodes” were used. “No ossification” was considered for terms like “little ossification, defined as ossification of <25%,”[18] or “no healing” and “no progression of the lesion and no healing.”[10]
There was a large degree of imprecision and inconsistency in the terms used to describe clinical outcomes. Therefore, patients were considered “Functional” if they were reported as “functional,” “able to perform activities of daily living,” “having a full range of motion,” or with “no functional restrictions.” “Mild and moderate functional derangement (FD)” were considered when similar terms were found.[8] “Severe FD” was considered for terms such as “bladder and bowel dysfunction,”[19] “postoperative absent bowel and bladder function,”[20] or “patient’s functional ambulation which was markedly compromised.”[21]
Pain severity was categorized into “mild,” “moderate,” or “no pain,” “Recurrence” was considered as a reappearance of the tumor in the radiographs at least 6 weeks after intervention. Terms such as “disease free,” “tumor free,” or “no recurrence seen” were considered as “no recurrence.”
The information available on radiological and clinical outcomes was summarized according to the treatment method. Whenever information on the variables collected was not specified in the article, it was documented as not reported (NR).
The quality and study design of the articles included in this systematic review did not allow a meta-analysis. Therefore, summary measures, synthesis of results, risk of bias across studies, publication bias, and treatment effect and heterogeneity assessment could not be performed. Given the low level of evidence available, a formal quality assessment was not considered necessary.
Individual patient data were aggregated according to treatment received and descriptive statistics were applied using “StataCorp 2017.”
RESULTS
A total of 143 records were identified through database searching and cross-referencing retrieved articles. After removing duplicates, 123 records were screened for eligibility [Figure 1]. After reviewing the title and abstracts, 55 records were excluded from the study. From the remaining 68 records, full-text articles were reviewed for eligibility, and 19 were omitted. Among the 19 excluded articles, 16 did not report any outcomes for specific treatment of pelvic ABC and three had a follow-up of <1 year.
- Flow diagram to explain the methodology of the systematic review of pelvic aneurysmal bone cyst.
The final number of studies included in the systematic review was 49, of which 29 were case reports and 20 were case series, spanning from 1979 to 2017. From the 49 studies, data were extracted from 194 patients into an excel sheet.
Treatment groups and patients included per study
Many treatment options were identified and grouped into five major treatment groups: observation, adjuvant, minor surgery, major surgery, and combined. These major treatment groups were further subdivided into 11 distinct treatment subgroups. The number of studies and patients included in each treatment group are described in [Table 1]. Some studies appeared in more than one treatment group.
| Treatment groups | Subgroups | No. Of studies | Studies included in the systematic review | Publication year | No. of ptsaper study | Total no. of ptsa |
|---|---|---|---|---|---|---|
| Observation | - | 5 | McQueen[43] Capanna et al.[19] Cottalorda et al.[10] Louahem[44] Huschild[29] |
1985 1986 2005 2012 2016 |
2 3 3 4 1 |
13 |
| Adjuvant | SAEb | 11 | Wallace et al.[31] Misasi[45] Murphy[46] Keller[47] Cisneros[48] De Cristofaro et al.[30] Rossi et al.[17] Rossi[49] Doss[50] Do Brito et al.[51] Milan[52] |
1979 1982 1982 1983 1985 1992 2010 2012 2014 2015 2016 |
1 2 1 2 1 5 22 1 1 1 1 |
38 |
| Sclerotherapy | 5 | Flappa[33] Dubios[34] Docquier and Delloye[24] Bush[53] Brosjo et al.[35] |
2002 2003 2005 2010 2013 |
1 1 2 1 5 |
10 | |
| Radiotherapy | 2 | Capanna et al.[19] Elsayad et al.[25] |
1986 2017 |
4 1 |
5 | |
| SAEb+sclerotherapy | 4 | Dubois et al.[34] Docquier and Delloye[24] Bush[53] Simm[54] |
2003 2005 2010 2013 |
1 1 1 1 |
4 | |
| Minor surgery | Curettage | 9 | Capanna et al.[19] Abdullah[28] Papagelopoulos et al.[8] Cottalorda et al.[10] Brastianos et al.[18] Puri et al.[20] Ozdemir[55] Huschild[29] Elsayad et al.[25] |
1986 1986 2001 2005 2009 2009 2011 2016 2017 |
11 1 15 9 2 1 1 4 1 |
45 |
| Extended curettage | 4 | Khan[56] Kim[57] Novais et al.[9] Hetaimish[58] |
2010 2014 2014 2016 |
1 1 8 1 |
11 | |
| Major surgery | Marginal excision | 6 | Capanna et al.[19] Malghem[59] Papagelopoulos et al.[8] Huang[60] Brastianos et al.[18] Rao[61] |
1986 1989 2001 2004 2009 2013 |
3 1 17 1 3 2 |
27 |
| Wide excision | 5 | Papagelopoulos et al.[8] Honl et al.[37] Yu et al.[36] Puri[20] Sharifah et al.[22] |
2001 2003 2007 2009 2011 |
1 1 1 1 1 |
5 | |
| Combined | Adjuvant+minor surgery | 13 | Wallace et al.[31] Dick[60] Capanna et al.[19] Delloye et al.[23] Papagelopoulos et al.[8] Wathiong[61] Docquier and Delloye[24] Cottalorda et al.[10] Yildirim[64] Brastianos et al.[18] Novais et al.[9] Rossi[65] Syvanen[66] |
1979 1979 1986 1996 2001 2003 2005 2005 2007 2009 2014 2015 2017 |
1 1 2 1 2 1 2 3 2 4 5 1 1 |
26 |
| Adjuvant+major surgery | 6 | Cheah[67] Papagelopoulos et al.[8] Pogoda[68] Brastinos[18] van de Luijtgaarden[26] Sobeai[39] |
1999 2001 2003 2009 2009 2015 |
1 5 1 1 1 1 |
10 |
Within the five major treatment groups, more than half of the patients, 113/194 (58%), were treated either with adjuvant 57/194 (29%) or minor surgery 56/194 (29%). In contrast, observation was the least used treatment accounting for only 13/194 (7%) patients.
Looking at treatment subgroups, most patients were treated with curettage 45/194 (23%) followed by SAE 38/194 (20%). Among the latter, 18 (47%) patients had only one SAE session, 10 (26%) patients had two, and further, ten patients had three sessions of SAE. Diverse biomaterials such as gel foam, latex particles, biospheres, isobutyl 2 cyanoacrylate, polyvinyl alcohol, and stainless-steel coils were used for the embolization.
Marginal excision was the third most commonly used treatment, 27/194 (14%), whereas wide excision was used only in five cases. The terms marginal and wide are derived from the “Enneking classification of surgical margins,” which is a standard reported measurement of surgical margins in osseous and soft-tissue tumor surgery.[22] Various materials have been described to fill the bony voids after major or minor surgery, such as autologous bone grafts, allografts, bone cement, bioactive glass, plexur M biocomposite, arthrodesis with plating, and vascularized fibular grafts.
The combined treatment groups included any type of surgery along with either SAE, sclerotherapy, or radiotherapy. The combined group of minor surgery + adjuvant was the fourth most used treatment (26/194). Most of these patients received SAE as a neoadjuvant treatment.
Extended curettage was used in 11/194 cases and reportedly done through high-speed burr, phenol, or ethanol washes. Sclerotherapy (10/194 cases) was either performed percutaneously or through a mini-open approach under fluoroscopy and general anesthesia. The sclerosants used were ethibloc, demineralized bone matrix combined with autologous bone graft, 32 P chromic phosphate, and polidocanol. The least used methods included radiotherapy (5/194), wide excision (5/194), and SAE with sclerotherapy (4/194). Radiotherapy has been used as a neoadjuvant but also as an adjuvant and treatment for recurrence. The maximum dosage received by any patient was 6000 Gy (Gray).
Demographics, radiological, and functional outcomes were summarized according to the treatment subgroup.
Demographics
Patient demographics per treatment subgroup are described in [Table 2]. Of the 194 patients, 91 (47%) were female, 101 (52%) were male, and gender was NR for two (1%) patients. The overall median age was 15 years, ranging from 1.5 to 64 years old. The median age among the different treatment subgroups was very similar and within the second decade of life except for the wide excision group.
| Treatment groups | Subgroups | No. of ptsa | Median age (min-max) yrsb | Gender n (%) | Median follow-up (min–max) yrsb | ||
|---|---|---|---|---|---|---|---|
| Female | Male | NRc | |||||
| Observation | - | 13 | 13 (10.5–46) | 5 (38) | 8 (62) | - | 2.8 (0.4–11) |
| Adjuvant | SAEd | 38 | 16 (3–33) | 18 (47) | 20 (53) | - | 1.75 (0.6–8) |
| Sclerotherapy | 10 | 13.5 (5–28) | 5 (50) | 5 (50) | - | 1.5 (0.9–4.3) | |
| Radiotherapy | 5 | 15 (8–22) | 1 (20) | 4 (80) | - | 7 (2.1–14) | |
| SAEd+Sclerotherapy | 4 | 13.5 (8–22) | 1 (25) | 2 (50) | 1 (25) | 3.35 (1.5–5.6) | |
| Minor surgery | Curettage | 45 | 15 (1.5–64) | 18 (40) | 27 (60) | - | 5 (1.2–45) |
| Extended curettage | 11 | 13.9 (5–17.5) | 5 (45) | 6 (55) | - | 6 (0.6–19.8) | |
| Major surgery | Marginal excision | 27 | 14 (6–60) | 13 (48) | 14 (52) | - | 7 (1–42) |
| Wide excision | 5 | 21 (15–51) | 3 (60) | 2 (40) | - | 11 (3–19) | |
| Combined | Adjuvant+minor surgery | 26 | 13.5 (4–38) | 17 (65) | 8 (31) | 1 (4) | 4.5 (0.6–24) |
| Adjuvant+major surgery | 10 | 16.5 (10–57) | 5 (50) | 5 (50) | - | 5.25 (1–53) | |
The mean time from the start of the symptoms to diagnosis was 10 months, ranging from 2 weeks to 10 years. The median follow-up was 3 years, with the longest follow-up of 53 years in a 10-year-old with stage 2 ABC in the sacrum treated with extended curettage and radiotherapy.[8]
Tumor characteristics
Main tumor characteristics in terms of size, anatomic location within the pelvis, and Enneking staging according to treatment group and subgroup are described in [Table 3]. Only 8 (4%) patients presented with a recurring ABC; the rest were all primary de novo lesions.
| Treatment groups | Subgroups | No. of ptsa | *Mean size cmb | Pelvic zone location n(%) | Enneking staging n (%) | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Single zone | Two zones | Three zones | |||||||||||||||
| 1c | 2d | 3e | 4f | 1+2 | 1+3 | 1+4 | 2+3 | 1+2 + 3 | 1+2 + 4 | 1 | 2 | 3 | NRg | ||||
| Observation | - | 13 | 4.5 | 1 (8) | 1 (8) | 5 (38) | - | - | 1 (8) | - | 1 (8) | 4 (30) | - | 1 (8) | 4 (31) | 7 (53) | 1 (8) |
| Adjuvant | SAEh | 38 | 7.3 | 12 (32) | 2 (5) | 15 (40) | 7 (18) | - | - | 2 (5) | - | - | - | - | 16 (42) | 12 (32) | 10 (26) |
| Sclerotherapy | 10 | 7.68 | 1 (10) | 1 (10) | 3 (30) | 2 (20) | - | 1 (10) | - | 2 (20) | - | - | - | 1 (10) | 9 (90) | - | |
| Radiotherapy | 5 | NR | - | - | - | - | - | 3 (60) | 1 (20) | - | 1 (20) | - | - | - | - | 5 (100) | |
| SAEh+ Sclerotherapy | 4 | 7.83 | - | - | - | 2 (50) | - | 1 (25) | - | - | 1 (25) | - | - | - | 1 (25) | 3 (75) | |
| Minor surgery | Curettage | 45 | 22.5 | 8 (17) | 2 (4) | 8 (17) | 11 (24) | 2 (4) | 4 (8) | 1 (2) | 4 (8) | 5 (11) | - | 1 (25) | 15 (33) | 23 (51) | 6 (13) |
| Extended curettage | 11 | 11 | 1 (9) | - | 7 (63) | 3 (27) | - | - | - | - | - | - | 8 (72) | 3 (27) | - | ||
| Major surgery | Marginal excision | 27 | 10.8 | 2 (7) | - | 4 (15) | 8 (30) | 2 (7) | 1 (10) | - | 10 (37) | - | - | - | 7 (26) | 19 (70) | 1 (4) |
| Wide excision | 5 | 18.5 | - | 1 (20) | - | 1 (20) | 1 (20) | - | 1 (20) | - | 1 (20) | - | - | 4 (75) | 1 (25) | ||
| Combined | Adjuvant+ minor surgery | 26 | 7.77 | 2 (8) | 2 (8) | 5 (19) | 6 (23) | 5 (19) | 2 (8) | - | 3 (12) | 1 (3) | - | - | 6 (23) | 17 (65) | 3 (12) |
| Adjuvant+ major surgery | 10 | 21.5 | 1 (10) | - | 1 (10) | 4 (40) | 3 (30) | - | - | 1 (10) | - | - | - | 1 (10) | 9 (90) | - | |
The information on tumor size for individual patients was available for only 50/194 patients (25%). However, for 22 (11%) patients, tumor size was described in categories of less than, up to, or >5 cm.[18] The minimum reported tumor size was 3 cm and the maximum 30 cm. The treatment groups with an average size above 15 cm were all surgical (either as a standalone treatment or combined with adjuvant therapy). In contrast, tumors in the observation group were, on average 4.5 cm and were followed up with a median of 2.8 years.
Most tumors (126/194) were located within one pelvic zone, with a majority of them in the ischiopubic area (zone 3). Only 13/194 occupied three zones: ilium, acetabulum, and ischiopubic area in all except one case (zones 1 + 2 + 3). The most frequent combination for tumors within two zones was acetabulum and ischiopubic area (zones 2 + 3), followed by ilium and acetabulum (1 + 2), and ilium and ischiopubic (zones 1 + 3). Tumors involving both the ilium and sacrum (zones 1 + 4) were found only in four cases.
The Enneking staging divides benign bone tumors into three categories: latent (stage 1), active (stage 2), and aggressive (stage 3).[23] Over 50% of the cases were Enneking stage 3, and 30% were stage 2. The staging was not mentioned for 30 (15%) patients.
Outcomes
Radiological and clinical outcomes per treatment group are detailed in [Table 4]. Given that the radiological and functional outcomes reported in the retrieved studies were remarkably inconsistent, heterogenous, and, on occasions, extremely vague, we tried to categorize the outcomes following our best interpretation and understanding of what was reported by the authors. Only one study[9] described the outcomes using the musculoskeletal tumor rating scale, Toronto extremity salvage score, and the 36-item short-form health survey.
| Treatment | Subgroups | No. of ptsa | Ossificationn (%) | Functional outcomen (%) | Painn (%) | Recurrencen (%) | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Yes | Partial | No | NRb | Functionalc | Mild FDd | Moderate FDe | Severe FDf | NRb | No pain | Mild | Moderate | NRb | Yes | No | NRb | |||
| Obsg | - | 13 | 9 (69) | 3 (23) | - | 1 (8) | 12 (92) | - | - | - | 1 (8) | 12 (92) | - | 1 (8) | 1 (8) | - | 12 (92) | 1 (8) |
| Adjuvant | SAEh | 38 | 28 (74) | 7 (18) | 3 (8) | - | 14 (37) | - | - | - | 24 (63) | 14 (37) | - | - | 24 (63) | 1 (3) | 37 (97) | - |
| Sclerotherapy | 10 | 10 (100) | - | - | - | 8 (80) | - | - | - | 2 (20) | 8 (80) | - | - | 2 (20) | - | 9 (90) | 1 (10) | |
| Radiotherapy | 5 | 4 (80) | 1 (20) | - | - | 1 (20) | - | 2 (40) | 1 (20) | 1 (20) | 2 (40) | 2 (40) | 1 (20) | - | 1 (20) | 4 (80) | - | |
| SAEh+ Sclerotherapy | 4 | 4 (100) | - | - | - | 1 (25) | - | - | - | 3 (75) | 1 (25) | - | - | 3 (75) | - | 4 (100) | - | |
| Minor surgery | Curettage | 45 | 34 (75) | 5 (11) | 1 (2) | 5 (11) | 40 (88) | 2 (4) | - | 2 (4) | 1 (2) | 34 (75) | 6 (13) | 1 (2) | 4 (8) | 9 (20) | 30 (66) | 6 (13) |
| Extended curettage | 11 | 11 (100) | - | - | - | 8 (72) | 1 (9) | 1 (9) | - | 1 (9) | 3 (27) | - | - | 8 (72) | 1 (9) | 9 (81) | 1 (9) | |
| Major surgery | Marginal excision | 27 | 23 (85) | - | - | 4 (14) | 22 (81) | 3 (11) | 1 (3) | 1 (3) | 19 (70) | 4 (14) | - | 4 (14) | 2 (7) | 24 (88) | 1 (3) | |
| Wide excision | 5* | 3 (60) | - | - | 1 (20) | 2 (40) | 1 (20) | - | - | 1 (20) | 1 (20) | 1 (20) | 1 (20) | 1 (20) | 1 (20) | 2 (40) | 1 (20) | |
| Combined | Adjuvant+ minor surgery | 26 | 16 (61) | 3 (11) | - | 7 (26) | 15 (57) | 3 (11) | 2 (7) | - | 6 (23) | 12 (46) | 1 (3) | 1 (3) | 12 (46) | 3 (11) | 19 (73) | 4 (15) |
| Adjuvant+ major surgery | 10* | 8 (80) | - | 1 (20) | - | 7 (70) | 1 (10) | 1 (10) | - | - | 6 (60) | 2 (20) | - | 1 (10) | 3 (30) | 6 (60) | - | |
Our primary outcome focused on ossification. In total, 150 patients (77%) had complete ossification, 19 patients (10%) had partial, and five patients (2%) had no evidence of ossification. The ossification status was unavailable in 20/194 cases: in 18 patients (9%), it was NR, and two patients (1%) died during or shortly after surgery.
Clinical outcomes related to function, pain, and recurrence. Patients were reported as functional in 140 (72%) cases. However, mild FD was seen in 11 patients (6%), moderate in 6 (3%), severe in 4 (2%), and in 41 (21%), the functional outcome was NR. At the end of the follow-up, 112 patients (58%) reportedly had no pain, whereas mild pain was mentioned in 16 (8%) patients, moderate pain in 5 (2%) patients, and 50 patients (30%), the pain was NR.
Overall, the incidence of recurrence was low. Recurrence was reported in 21 (10.8%) patients and NR in 15 patients (8%), whereas the remaining patients had no recurrence at the time of the last follow-up. The longest time to recurrence was 6 years in a 13-year-old male patient with an ABC in the pubis extending to the acetabulum treated with an extended curettage.[8] Recurrence was treated mostly by curettage or excision and autologous bone grafting. Few recurrent cases were managed with scleroembolic treatments instead of surgery[24] and three cases were treated with radiotherapy.[22,25] Curettage had a relatively high number of recurrences compared to the other treatments. However, the unbalanced group size and a low number of patients in some subgroups preclude a proper statistical analysis.
The number of reported complications is low. Hemorrhage was reported in six (3%) patients who were treated with surgery (five patients) and sclerotherapy (one patient). Of these, one patient died secondary to massive bleeding. Neurological complications were described in 13 (7%) patients. These include hypoesthesia, bowel and bladder dysfunction or residual loss of bowel, bladder control, neuroma formations, and involvement of sacral roots, sciatic nerve, obturator nerve, and caudal sac. Eleven (6%) patients with neurological complications had ABC located in zone 4 (sacral), while the remaining two were in zones 2 and 3. One patient with a tumor in zones 2 and 3 had partial encasement of the bladder with the ABC mass resulting in subtotal cystectomy. Limb length discrepancy (0.6 – 3cm) was reported in four patients (2%) after marginal resection of ABC. Curettage in the sacrum (pelvic zone 4) was performed in 12 (26%) cases and had frequent reports of hemorrhage, bowel injury, dural tear, and loss of bowel bladder control. Nine out of 21 (42%) patients had complications after treatment for recurrence. Capanna et al. reported three cases, in which the primary treatment was radiotherapy or a combination of radiotherapy with surgery. Recurrence was observed and treated with curettage or radiotherapy. These patients were left with residual complications of crural nerve palsy, quadriceps, psoas deficit, and femoral head necrosis.[20]
Two patients died of treatment-related complications in this series of 194 cases reported in the literature. A 51-year-old female with a 25 × 25 × 20 cm ABC in the right ilium extending into the ischium. The patient was treated surgically and died of profuse perioperative bleeding.[26] The second case was a 48-year-old female with a 27.6 × 22.4 × 15.9 cm lesion in the left ilium with a history of embolization, sclerotherapy, and repeated surgery. The authors performed pre-operative embolization and percutaneous intralesional alcohol injection. This was followed by staged near-total resection combined with cryosurgery and off-label systemic treatment with bevacizumab, a monoclonal anti-vascular endothelial growth factor antibody, to reduce bleeding. The patient developed clinical heart failure, prompting the discontinuation of bevacizumab, followed by a rapid regrowth of the pelvic lesion. After seven surgical sessions, the patient’s condition no longer allowed further interventions and she was treated with radiotherapy. The patient died 2 years after ABC was first diagnosed.[27]
ABC in the pelvis has also been described in two pregnant women. A pelvic bone lesion in pregnancy can be difficult for the obstetrician to determine the effect of parturition on the pelvic bone.[28] The first reported case was in 1986 of a right iliac ABC measuring 15 cm in a 19-year-old primigravida. At the time of the elective caesarian section, the mass was excised through a separate lumbar approach. No recurrence or complication was reported.[29] The second reported case was a 6.1 × 2.9 × 6 cm lesion in the left ilium of a 26-year-old primigravida who had a successful elective cesarian section, and the ABC was observed until the last follow-up at 3 months.[28]
We, further, analyzed tumor characteristics and clinical and radiological outcomes according to their pelvic zone location and the results are summarized in [Table 5]. While zone 3 was overall the most common tumor location 48/194 (25%), when taking into consideration tumors with overlapping zones as well, most patients 74/194 (38%) had an affection of zone 1 – ilium; of these 14 had partial ossification and the functional outcome was NR in half of them. Tumors in zone 4 sacrum had more neurological complications reported, such as bladder and bowel dysfunction.[19] Moderate residual pain was mentioned in 4/194 patients located in zones 4, 2 + 3, and 1 + 2 + 3. Moreover, severe FD reported in 4/194 were located in zone 4 (3 cases) and zone 1 + 3 (1 case).
| Pelvic Zones | No. of ptsa | #Mean size (cm)b | Enneking stage n(%) | Ossification n(%) | Functional outcome n(%) | Pain n(%) | Recurrence n(%) | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | 2 | 3 | NRc | Yes | Partial | No | NRc | Functionald | Mild FDe | Moderate FDf | Severe FDg | NRc | No pain | Mild | Moderate | NRc | Yes | No | NRc | |||
| 1* | 28 | 10 | 1 (4) | 11 (39) | 10 (36) | 6 (21) | 15 (53) | 10 (35) | 2 (7) | - | 14 (50) | - | - | - | 13 (46) | 12 (42) | 2 (7) | - | 13 (46) | 6 (21) | 20 (71) | 1 (3) |
| 2 | 9 | 9.06 | - | 2 (22) | 6 (67) | 1 (11) | 7 (77) | 1 (11) | - | 1 (11) | 8 (88) | - | - | - | 1 (11) | 7 (77) | - | - | 2 (22) | - | 9 (100) | - |
| 3 | 48 | 8.2 | 1 (2) | 20 (41) | 19 (40) | 8 (17) | 41 (85) | 4 (8) | 2 (4) | 1 (2) | 36 (75) | 1 (2) | 1 (2) | - | 10 (20) | 31 (64) | - | - | 17 (35) | 3 (6) | 40 (83) | 5 (10) |
| 4 | 41 | 11.6 | - | 9 (22) | 26 (63) | 6 (15) | 28 (68) | - | - | 13 (31) | 23 (56) | 6 (15) | - | 3 (7) | 9 (21) | 18 (37) | 5 (12) | 2 (4) | 16 (39) | 6 (15) | 35 (85) | - |
| 1+2 | 15 | 7.5 | - | 5 (33) | 10 (67) | - | 13 (86) | - | - | 1 (6) | 9 (60) | 4 (26) | 1 (6) | - | 1 (6) | 7 (46) | 2 (13) | - | 6 (40) | 2 (13) | 13 (87) | - |
| 1+3* | 14 | 15.5 | - | 4 (29) | 10 (71) | - | 11 (78) | 1 (7) | 1 (7) | - | 8 (57) | - | 1 (7) | 1 (7) | 3 (21) | 8 (57) | 2 (14) | - | 3 (21) | 3 (21) | 9 (64) | 1 (7) |
| 1+4 | 4 | NRc | - | 1 (25) | 2 (50) | 1 (25) | 3 (75) | 1 (25) | - | - | 3 (75) | - | - | - | 1 (25) | 3 (75) | 1 (25) | - | - | - | 4 (100) | - |
| 2+3 | 22 | 7.75 | - | 5 (23) | 17 (77) | - | 21 (95) | 1 (5) | - | - | 21 (95) | - | 1 (5) | - | - | 18 (81) | 3 (13) | 1 (5) | - | 1 (5) | 20 (90) | 1 (5) |
| 1+2 + 3 | 12 | 11 | - | 2 (17) | 10 (83) | - | 8 (66) | 1 (8) | - | 3 (25) | 8 (66) | - | 1 (8) | - | 3 (25) | 7 (58) | 1 (8) | 1 (8) | 3 (25) | 1 (8) | 7 (58) | 4 (33) |
| 1+2 + 4 | 1 | NRc | - | - | 1 (100) | - | 1 (100) | - | - | - | - | - | - | - | 1 (100) | 1 (100) | - | - | - | - | - | 1 (100) |
DISCUSSION
A pelvic ABC is a treatment challenge. Most cases have been managed with individualized treatment plans tailored to their size, stage, location, behavior, available clinical resources, and surgical expertise. In this systematic literature review, we were able to successfully categorize these varied treatments for 194 patients of pelvic ABC in five groups and 11 sub-groups. This is not only a useful overview of existing therapeutic modalities but also suggests the variability that exists in choosing the best treatment modality.
We could identify only 194 patients of pelvic ABC, fulfilling our inclusion criteria since 1979, which emphasizes the rarity of the problem. In our study, the gender distribution of pelvic ABC had a slight male predominance in 52% of the cases. The median age was 15 years, although the range was quite wide, from 1.5 years to 65 years. Most lesions grow significantly, become stage 3, and remain asymptomatic before being diagnosed. Among the 194 reported treated cases in the literature, 60% showed complete radiological ossification, 72% were reported functional, and 10.8% had a recurrence. These results indicate that most pelvic ABCs have a good prognosis in general.
Curettage with bone grafting is the most preferred treatment method, followed by SAE either alone or in combination with surgery. In the curettage treatment group, 75% had radiological ossification with no pain and 88% were “functional” after treatment.[8,9,19,20,30] It was used in all pelvic zones and for any tumor stage. The maximum reported size for a lesion treated with curettage alone was 30 × 30 × 20 cm in zone 4 in a 14-years-old.[25]
SAE is described in the literature as a simpler, cheap, easily repeatable, less invasive, or less risky procedure. It has been used in patients at extreme ages, the youngest being 1.5 and the oldest 64 years. Surgery and radiotherapy were the main treatment modalities for ABC until the introduction of SAE.[31] The earliest records of SAE for pelvic ABC come from Wallace et al. in two patients. They reported a 15% reduction in size and pain-free status after 1 year in one 27-year-old female patient with an ABC in the ilium. The second patient, a 38-year-old male, was reported to have surgery and cordotomy followed by SAE. The patient remained pain-free at 5 years follow-up but had a recurrence later.[32]
Varshney et al. did a comparative study to determine the healing rate and functional score between two groups treated with sclerotherapy (polidocanol) or intralesional curettage. They concluded that “although the healing rates were similar, we found higher rates of clinically important complications, worse functional outcomes, and higher hospital burden associated with intralesional excision.” They called it a preliminary study and recommended larger studies to confirm their findings.[33] In this review, a comparison of the two groups was not possible due to a large discrepancy in patient number 45 in curettage versus 10 in the sclerotherapy group. Moreover, due to the poor quality of reporting outcomes, the reliability of the results is questionable.
In most recent studies reviewed, scleroembolic procedures are used as adjuncts or combined with major surgical procedures in large pelvic tumors.[33-36] Papagelopoulos et al. set five cm as a cut-off for performing a curettage or excisional surgery.[8] We observed in the systematic review that tumors >15 cm were all treated surgically either alone or combined with adjuvants. However, we cannot say if this is the best treatment in such cases. Following an excisional surgery, some major mechanical complications are reported, such as hip dislocation/subluxation, protrusio acetabuli, and limb length discrepancy.[8] However, according to the reports, the key to overcoming these issues is to get a near anatomic reconstruction of the pelvic defects. At present, tricortical iliac crest grafts, vascularized or non-vascularized fibular grafts, allografts, custom-made mega prosthesis, extracorporeal irradiated pelvic bone, and re-implantation have all been described.[19,21,37-39] Zidzislaw et al. predicted that the future for pelvic defects is a statistical shape model reconstruction method using a mirroring approach.
Since the anatomic location of the tumor influences the treatment strategy and prognosis, we analyzed the results by pelvic zone. Patients with tumors in zone 4 accounted for most of the neurological complications reported, whereas half of the cases with hemorrhage, including a deadly case, were located in zone 1. In their series of 13 pelvic ABCs in children, Novais et al. observed higher recurrence rates in open physis and suggested that destructive lesions in triradiate cartilage can lead to long-term complications.[9] In our results, we observed that 3/4 of patients with limb length discrepancy had their ABCs near the triradiate cartilage, that is, zones 2 and 3. In summary, the particular neighboring structures and their involvement require modified treatment methods for better outcomes, as Papagelopolus concluded.[8]
The minimum average tumor size per treatment group was 4.5 cm (observation), whereas the maximum average size was 22.5 cm (curettage). However, when the results are grouped by pelvic zones, the average diameter ranges only from 7.5 to 15.5 cm. This might suggest that in addition to the anatomic location, the tumor size also has some influence on the treatment method since the average size by pelvic zone is similar. However, since tumor size was only available for 25% of patients, these results should be interpreted with great caution.
Denosumab is a human monoclonal antibody that prevents the cytokine receptor activator of nuclear factor-kappa B ligand from activating the RANK receptor of osteoclasts, inhibiting osteoclast function. Denosumab is highly effective in giant cell tumors of bone (GCT), and therefore, similar effects in principle could be hoped for in ABC, which has distinct similarities to GCT. Up to now, no protocol or treatment recommendation for the use of denosumab in ABC exists. Dürr et al., while concluding off-label use of Denosumab in six patients of ABC (out of which two were sacral, one pelvic in location), suggest it as an adjuvant option in anatomically challenging locations and local recurrence. However, they reported severe rebound hypercalcemia in young patients.[40] Since this systematic review was compiled in September 2017; these reports are not part of the results.
The limitations of our systematic literature review are mainly due to the low evidence found, which was mostly restricted to retrospective case reports and case series. This was, further, hampered by the heterogeneous reporting and inconsistent outcome measurements, which precluded a meta-analysis. The systematic review was performed in September 2017, so reports published after that are not included in this study.
CONCLUSION
Pelvic ABC has been documented in medical literature as case reports or case series and with heterogeneous reporting. In this systematic literature review, individual patient data were extracted to give an overview regarding functional and radiological outcomes by treatment modality.
Although mostly benign, pelvic ABC has unpredictable behavior. A clear trend is being adopted toward using neoadjuvant scleroembolic treatments alone or combined with surgery for better radiological and functional outcomes.
RECOMMENDATIONS
We encourage reporting of surgical case reports following a standard reporting guideline like the SCARE statement (http://www.scareguideline.com/) to strengthen the quality of reporting.[41,42]
ACKNOWLEDGMENT
The present research work was supported by AOTrauma in the form of a clinical research fellowship at AOCID granted to the first author. We are grateful to the AOCID staff, and in particular to Vasiliki Kalampoki, for her help in data analysis. We also acknowledge the contribution of Prof Syed Muhammad Awais, Dean Faculty of Health Sciences, University of Punjab, Lahore, Pakistan, for his generous sharing of knowledge, constant support, and for being a source of inspiration.
ETHICAL APPROVAL
An ethics statement is not applicable, because this study is based exclusively on published literature.
AUTHORS’ CONTRIBUTIONS
The authors confirm contribution to the paper as follows: study conception and design, draft manuscript preparation: AS, ER and AHC. AHC and AS mainly performed the analysis and interpretation of results. Data collection was done by AS. All authors have critically reviewed and approved the final draft and are responsible for the manuscript’s content and similarity index.
DECLARATION OF PATIENT CONSENT
Patients consent is not applicable, because this study is based exclusively on published literature. FINANCIAL SUPPORT AND SPONSORSHIP
This study did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
CONFLICTS OF INTEREST
There are no conflicting relationships or activities.
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