[Giant cell tumor of bone-an update]. / Der Riesenzelltumor des Knochens ­ ein Update.

In the past few years, numerous new insights have been gained in the field of giant cell tumor of bone (GCTB). On the one hand, the detection of the highly characteristic histone mutation in the H3F3A gene in GCTB is becoming increasingly important in diagnostics in differentiating GCTB from other giant cell-rich lesions of bone as well as for defining rare variants of GCTB without osteoclastic giant cells. On the other hand, the effects of the H3F3A mutation were shown to have an impact on the epigenetic profile of tumor-driving stromal cells, providing new insights into tumorigenesis of GCTB.

DNA methylation profile discriminates sporadic giant cell granulomas of the jaws and cherubism from their giant cell-rich histological mimics.

Sporadic giant cell granulomas (GCGs) of the jaws and cherubism-associated giant cell lesions share histopathological features and microscopic diagnosis alone can be challenging. Additionally, GCG can morphologically closely resemble other giant cell-rich lesions, including non-ossifying fibroma (NOF), aneurysmal bone cyst (ABC), giant cell tumour of bone (GCTB), and chondroblastoma. The epigenetic basis of these giant cell-rich tumours is unclear and DNA methylation profiling has been shown to be clinically useful for the diagnosis of other tumour types. Therefore, we aimed to assess the DNA methylation profile of central and peripheral sporadic GCG and cherubism to test whether DNA methylation patterns can help to distinguish them. Additionally, we compared the DNA methylation profile of these lesions with those of other giant cell-rich mimics to investigate if the microscopic similarities extend to the epigenetic level. DNA methylation analysis was performed for central (n = 10) and peripheral (n = 10) GCG, cherubism (n = 6), NOF (n = 10), ABC (n = 16), GCTB (n = 9), and chondroblastoma (n = 10) using the Infinium Human Methylation EPIC Chip. Central and peripheral sporadic GCG and cherubism share a related DNA methylation pattern, with those of peripheral GCG and cherubism appearing slightly distinct, while central GCG shows overlap with both of the former. NOF, ABC, GCTB, and chondroblastoma, on the other hand, have distinct methylation patterns. The global and enhancer-associated CpG DNA methylation values showed a similar distribution pattern among central and peripheral GCG and cherubism, with cherubism showing the lowest and peripheral GCG having the highest median values. By contrast, promoter regions showed a different methylation distribution pattern, with cherubism showing the highest median values. In conclusion, DNA methylation profiling is currently not capable of clearly distinguishing sporadic and cherubism-associated giant cell lesions. Conversely, it could discriminate sporadic GCG of the jaws from their giant cell-rich mimics (NOF, ABC, GCTB, and chondroblastoma).

H3F3A mutation as a marker of malignant giant cell tumor of the bone: A case report and review of literature.

Giant cell tumor of the bone (GCTB) is a locally aggressive lesion, which characteristically arises from the epimetaphyseal region of long bones. They occur commonly in the third or fourth decade of life with a slight female preponderance. Various lesions such as chondroblastoma, aneurysmal bone cysts, and nonossifying fibromas can mimic the radiologic appearance of giant cell tumors. However, the greatest challenge is to differentiate between a conventional GCTB, a malignancy arising in a giant cell tumor, and osteoclast-rich osteosarcomas. The presence of a histone gene mutation, H3F3A, involving the substitution of glycine 34 has been reported in more than 95% of GCTB. Immunohistochemical (IHC) analysis of the biopsy specimens for H3.3pG34W expression is a surrogate for gene analysis and can be used to establish the presence of GCTB. Our report is the first in Indian literature to report the use of H3.3pG34W IHC in establishing the diagnosis of a primary malignant GCTB.

Significance of Histone H3.3 (G34W)-Mutant Protein in Pathological Diagnosis of Giant Cell Tumor of Bone.

OBJECTIVE: This study aimed to examine the expression of Histone H3.3 glycine 34 to tryptophan (G34W) mutant protein in Giant Cell Tumor of Bone (GCTB). METHODS: This analytic observation research used a cross-sectional study design on 71 bone tumors. The cases involved 54 tissue samples diagnosed as GCBT. It was divided into GCTB primer (n=37), recurrent GCTB (n=5), GCTB with metastasis (n=9), and malignant GCTB (n=3). There were 17 samples mimics of GCTB also tested, including chondroblastoma (n=1), giant cell reparative granuloma (n=2), giant cell of tendon sheath (n=7), chondromyxoid fibroma (n=2), aneurysmal bone cyst (n=2), and giant cell-rich osteosarcoma (n=3). The Immunohistochemistry was used to evaluate the expression of G34W-mutated protein in these bone tumors. RESULT: The representation H3.3 (G34W) was expressed in the nuclei of mononuclear stromal cells but not stained on osteoclast-like giant cells. This study was analyzed by the Chi-square test, Fisher's test, specificity test, and sensitivity test. We obtained p = 0.001 for Histone H3.3 (G34W) mutant expression in GCTB vs Non-GCTB. Statistically, there was no significant difference in the expression level of Histone H3.3 (G34W) in the GCTB and its variants p-value = 0.183. We also obtained that the specificity of Histone H3.3 expression on GCTB was 100% and the sensitivity of Histone H3.3 on GCTB was 77.8%. CONCLUSION: Histon H3.3 mutant as a mutated driver gene in an Indonesian GCTB can assist to diagnose GCTB and compare it from other bone tumors.

Giant cell tumor of bone with H3F3B mutation: A case report.

RATIONALE: Giant cell tumor of bone is a locally aggressive and rarely metastasizing neoplasm that typically affects the ends of long bones or the axial skeleton of young to middle-aged adults. As many as 69% to 100% of giant cell tumors harbor H3F3A gene mutations, while H3F3B gene mutations have rarely been reported. PATIENT CONCERNS: A 53-year-old male patient who underwent right distal femoral tumor resection. DIAGNOSES: Preoperative CT plain scan indicated giant cell tumor of bone with pathological fracture. Laboratory findings were as follows: serum calcium was 2.23 mmol/L (reference range: 2.1-2.55 mmol/L) and serum phosphorus was 1.35 mmol/L (reference range: 0.81-1.45 mmol/L). INTERVENTIONS: The histological morphology showed the typical features of a conventional GCT. The immunoprecipitation analysis results were as follows: H3.3G34W(-), H3.3G34R(-), H3.3G34V(-), and H3K36M(-). Sanger sequencing showed that the H3F3A and H3F3B gene mutations were wild type. The high-throughput gene sequencing results revealed the H3F3B gene mutations H3.3p.Gly35Trp and H3.3p.Val36Leu. OUTCOMES: The patient was stable with no recurrence in 12 months follow-up. LESSONS: Giant cell tumor of bone with H3F3B gene mutations is extremely rare. In the pathological diagnosis of bone tumors, we need to analyze clinical presentation, imaging features, histology, immunophenotype, and cytogenetic/molecular alterations, in order to get a correct diagnosis.

Anti-histone H3.3K36M Antibody is a Highly Sensitive and Specific Immunohistochemistry Marker for the Diagnosis of Chondroblastoma. A Validation Based on Study 136 Cases Comprising Chondroblastoma and its Mimics from Single a Centre in India.

Introduction. Chondroblastoma has a wide range of differential diagnosis encompassing various benign and malignant entities. The closest differential diagnosis is giant cell tumor of the bone due to overlapping radiological and histomorphological features. Extensive aneurysmal bone cyst like changes and lack of adequately sampled chondroid matrix often masquerades the primary bone lesion and amplifies the diagnostic difficulty in small biopsies with limited tissue. Immunohistochemistry is helpful in such instances to resolve the diagnostic dilemma. Objectives. To analyze the immunohistochemical expression of anti-histone H3F3K36M antibody inchondroblastoma and validate its utility in differentiating chondroblastoma from its histological mimics. Material and methods. Immunohistochemistry was performed using anti-histone antibody H3.3K36M in 44 histologically diagnosed chondroblastoma and 92 other histological mimickers. All chondroblastoma and giant cell tumor of the bone included in the study were also tested for anti-histone H3.3 G34W antibody. Of the 33 giant cell tumors of bone with classic morphology and imaging findings, 24 H3.3 G34W positive and 9 negative tumors were included intentionally to rule out the possibility of chondroblastoma. The sensitivity, specificity, positive and negative predictive value of marker with regard to chondroblastoma was calculated. Results. Immunohistochemistry revealed unequivocal nuclear positivity for H3.3K36M in the mononuclear cells in all the 44 chondroblastoma tested, denoting a sensitivity of 100% cases. Allthesetumors tested simultaneously for anti-histone H3.3G34W were negative. None of the histological mimickers were positive H3.3K36M indicating a specificity of 100%. The positive and negative predictive value was 100%. Conclusion. H3.3K36M mutant antibody is highly sensitive and specific IHC marker and can be used as a valuable adjunct to distinguish chondroblastoma from its histological mimics especially on small biopsies.

Giant Cell Tumor of Bone Without Giant Cells with a Long Clinical Course: A Case Report.

Giant cell tumor of bone (GCTB) consists of a mixture of neoplastic mononuclear cells and non-neoplastic cells, including polynuclear giant cells. Recently, with the spread of the immunohistochemical staining marker H3.3 G34W corresponding to specific genetic abnormalities, the histological diversity of GCTB has been recognized. GCTB without giant cells is uncommon, although it has also been reported previously. Herein, we describe a 45-year-old man with GCTB without giant cells who was successfully diagnosed using H3.3 G34W immunohistochemistry. Other unusual findings in GCTB that were identified in this patient include bone and osteoid formation with a long clinical course of 13 years. We also compared the histological findings of the current patient to those who received denosumab therapy.

Giant cell tumor of bone: An update, including spectrum of pathological features, pathogenesis, molecular profile and the differential diagnoses.

Giant cell tumor of bone (GCTB) is an enigmatic tumor. Despite its benign histological appearance and clinical behavior in most cases, it is associated with recurrences, uncommonly metastasis, and rarely with a malignant transformation. During the last few years, there has been a significant evolution in the diagnosis and management of GCTB, including discoveries related to the underlying pathogenesis (RANK/RANK/OPG pathway), with treatment-related implications in the form of denosumab (approved inhibitor for targeting RANKL), leading to improved surgical resections, especially in cases of recurrent, large and borderline resectable tumors. Lately, a specific Histone mutation, namely H3.3G34W underlying almost all GCTBs has been discovered, further leading to the identification of a highly sensitive and specific immunohistochemical antibody marker, H3.3G34W, which is very useful for an exact diagnosis of a GCTB, including its differentiation from its various mimics, which has significant implications. This review describes clinicopathological features of a GCTB, including its variable features, recent concepts, underlying pathogenesis, post-denosumab related changes and various entities that constitute its differential diagnosis, including their molecular signatures, with treatment-related implications.

Malignant Transformation of Giant Cell Tumour of Bone: A Review of Literature and the Experience of a Referral Centre.

Giant cell tumour of bone (GCTB) is a benign, locally aggressive primary bone neoplasm that represents 5% of all bone tumours. The principal treatment approach is surgery. Although generally GCTB is considered only a locally aggressive disease, it can metastasise, and lung metastases occur in 1-9% of patients. To date, only the use of denosumab has been approved as medical treatment for GCTB. Even more rarely, GCTB undergoes sarcomatous transformation into a malignant tumour (4% of all GCTB), but history of this malignant transformation is unclear and unpredictable. Considering the rarity of the event, the data in the literature are few. In this review, we summarise published data of GCTB malignant transformation and we analyse three cases of malignant transformation of GCTB, evaluating histopathology, genetics, and radiological aspects. Despite the rarity of this event, we conclude that a strict follow up is recommended to detect early malignant transformation.

Combined fibrinogen and neutrophil-lymphocyte ratio as a biomarker in predicting recurrence of giant cell tumor of bone.

Aims: The present study investigated the combined clinical significance of fibrinogen and neutrophil-lymphocyte ratio (F-NLR) in predicting postoperative recurrence of giant cell tumor of bone. Methods: A total of 113 participants were included in this retrospective study to examine the effects of inflammatory factors on postoperative tumor recurrence. Results: The high-score F-NLR group was significantly associated with larger tumor size (p = 0.001), advanced tumor stage (p = 0.018), wide resection (p = 0.004) and greater local recurrence (p = 0.014). Univariate and multivariate survival analyses revealed that F-NLR (p = 0.035) remained an independent factor influencing tumor recurrence rates. Conclusions: This study reveals that the F-NLR score is a promising blood biomarker for predicting giant cell tumor recurrence.

Giant cell tumor of bone (GCT) is predominantly regarded as an intermediate, locally destructive but rarely metastasizing tumor with recurrence potential and peak incidence in the second to fourth decades of life. The treatment of GCT is often difficult due to local recurrence. Therefore, a new indicator is urgently needed to predict postoperative recurrence more accurately in patients with GCT. The preoperative combined fibrinogen and neutrophil­lymphocyte ratio as a predictor of tumor recurrence and prognosis in GCT patients has been assessed. The present study is the first to demonstrate that a grading system based on the fibrinogen and neutrophil­lymphocyte ratio score is an easily determined, meaningful and reproducible biomarker for predicting recurrence in GCT patients.

Anti-Histone H3.3 G34W antibody is a sensitive and highly specific immunohistochemistry marker for the diagnosis of Giant cell tumor of bone. A validation based on analysis of 198 cases from a single centre in India.

Context: The diagnosis of giant cell tumor of bone (GCTB) is difficult in small biopsies with unusual age of presentation, location, and extensive secondary changes. Most of the GCTBs harbor H3F3A G34W mutations with a subset of cases showing alternate G34V, G34R, and G34L mutations. Objectives: To analyze the expression of anti-histone H3.3G34W antibody in different cellular components of GCTB across different locations and presentations (including the unusual ones) and validate the utility of this antibody in the diagnosis of GCTB and differentiate it from the other osteoclast-like giant-cell-rich lesions. Design: Immunohistochemistry was performed using anti-histone H3.3G34W antibody in the diagnosed cases of GCTB (136 cases of GCTB from 133 patients, including two malignant GCTBs) and other giant cell-containing lesions (62 cases). The presence of unequivocal crisp nuclear staining was considered positive. Results: Immunohistochemistry revealed unequivocal nuclear positivity in the mononuclear cells in 87.3% of the cases of GCTB. Of these, most showed diffuse expression with moderate to strong intensity staining. The positive staining was restricted to the nuclei of mononuclear cells with the nuclei of osteoclastic giant cells being distinctly negative. In addition to conventional GCTBs, two cases each of multicentric and malignant GCTB showed positive staining. The other giant-cell containing lesions were distinctly negative. The present study showed a sensitivity of 87.3% with specificity and positive predictive value of 100%. Conclusion: The anti-histone G34W antibody is a highly sensitive and specific marker for the diagnosis of GCTB and differentiating it from its mimics. The positive staining is restricted to the mononuclear cell component of GCTB with sparing the osteoclastic giant cells further reiterating the fact that the mononuclear stromal cells are the true neoplastic component of GCTB.

Oestrogen receptor expression distinguishes non-ossifying fibroma from other giant cell containing bone tumours.

Non-ossifying fibroma (NOF) and central giant cell granuloma (CGCG) are both benign tumours of bone with overlapping morphology and similar mutations in the RAS/MAPK pathway. However, NOF is located in the long bones with regression after puberty in contrast to CGCG which is located in the jaw bones and does not regress spontaneously. We hypothesised that endocrine regulation by oestrogen plays a role in the spontaneous regression in NOF. Therefore, we examined the expression of ERα in a series of NOF and CGCG. ERα expression (EP1) was determined using immunohistochemistry on 16 NOFs (whole slides), and 47 CGCGs (tissue microarrays (TMA's n = 41 and whole slide n = 6)). As comparison, we included TMAs of other giant cell containing bone lesions: giant cell tumour of bone (n = 75), chondroblastoma (n = 12), chondromyxoid fibroma (n = 12), aneurysmal bone cyst (n = 6) and telangiectatic osteosarcoma (n = 6). All 16 NOF samples demonstrated ERα protein expression, while all 47 CGCG and all other giant cell containing bone tumours were negative. Most NOF samples had moderate staining intensity and between 24 and 49% of the spindle cells were ERα-positive. Our findings further support the role of endocrine regulation via oestrogen in the spontaneous regression in NOF. Whether oestrogen signalling at puberty is involved in the induction of senescence in the neoplastic cells of NOF harbouring RAS/MAPK pathway mutations needs further research. Since ERα expression was not observed in other giant cell containing bone lesions with overlapping morphological features, positive ERα expression may favour the diagnosis of NOF in challenging diagnostic cases.

Histopathological Features Of Denosumab Treated Giant Cell Tumours Of Bone "A Single Institutional Experience" At A Tertiary Care Center, Karachi.

BACKGROUND: Giant cell tumour (GCT) is a primary benign, locally aggressive bone tumour. Treatment is surgical however, denosumab has been increasingly used as a treatment in recurrent or unresectable locally advanced GCT because of its effect in reducing tumour size. Denosumab treated GCT can exhibit a wide array of histopathological features resulting in diagnostic problems for pathologists. Our study aimed at identifying these histopathological features to aid pathologists in reaching a correct diagnosis. METHODS: Our study included 20 patients of biopsy-proven GCT cases treated with denosumab. We received specimens for histopathological examination in our institution from January 2018 to March 2020. The demographic and clinical data of these patients were retrieved from the Health Management Information System (HMIS). The slides were retrieved and studied for histopathological changes. RESULTS: The mean age of patients in our study was 29.5 years. There were 11 males and 9 females. Distal radius was most commonly involved bone. On histopathological examination, ovoid to spindle mononuclear stromal cells were seen. Total absence of osteoclast like giant cells was seen in 10 (50%) cases, whereas 3 (15%) cases showed a marked reduction in osteoclast like giant cells. CONCLUSIONS: Denosumab treated GCT of bone can exhibit a wide spectrum of histopathological features. Pathologists need to be mindful of these features. Correlation of histopathological findings with clinical history and radiological features is important to prevent erroneous diagnosis. Treatment history of patients with denosumab is essential as incorrect diagnosis can be made if the history of denosumab treatment is not provided.

Giant cell tumor of hyoid bone: Diagnostic dilemma with a novel management.

Giant cell tumor of bone (GCTB) is locally aggressive tumor occurring in the epiphysis of long bones. GCTBs are uncommon tumors in the head-and-neck region and rarely involve hyoid bone. We report a case of GCTB of hyoid bone. The patient presented with swelling in left submandibular region. The tumor was surgically excised after initial denosumab therapy. Despite adequate resection and rehabilitation, he was tube dependent. Subsequently it was found that the patient had a coexisting myotonic dystrophy, unknown to exist with GCTB of hyoid. Eventually, the patient succumbed to respiratory failure secondary to myotonic dystrophy. GCTB hyoid is a rare presentation posing a diagnostic dilemma. Ours is the first case to report the use of denosumab for GCT in head-and-neck region. Myotonic dystrophy Type I and GCTB are both known to result from abnormality of closely situated foci on chromosome 19.

Diaphyseal giant cell tumor with multiple relapses in a skeletally immature patient: a case report.

Giant cell tumor (GCT) is an aggressive osteolytic lesion mostly affecting the meta-epiphyses of long bones at skeletal maturity. Occurrence of the GCT in diaphysis is a rare entity in adult and exceptionally rare in pediatric population. This is the only third diaphyseal case reported in pediatric population. We report a case of recurrent diaphyseal GCT in a skeletally immature patient of 15-year-old male at the right radius after previous resection with plate and screw fixation. Upon optimal investigations, en-bloc resection of the tumor with radial resection and ulna centralization with wrist arthrodesis was done for a campanacci stage III GCT. The patient had an uneventful recovery without recurrence for 2 years and 2 months following surgery. The main challenge relies on accurate diagnosis due to uncommon location that hinders adequate treatment plan, therefore diagnosis should be solely based on histopathology findings.

Diagnostic Utility of Genetic and Immunohistochemical H3-3A Mutation Analysis in Giant Cell Tumour of Bone.

To validate the reliability and implementation of an objective diagnostic method for giant cell tumour of bone (GCTB). H3-3A gene mutation testing was performed using two different methods, Sanger sequencing and immunohistochemical (IHC) assays. A total of 214 patients, including 120 with GCTB and 94 with other giant cell-rich bone lesions, participated in the study. Sanger sequencing and IHC with anti-histone H3.3 G34W and G34V antibodies were performed on formalin-fixed, paraffin-embedded tissues, which were previously decalcified in EDTA if needed. The sensitivity and specificity of the molecular method was 100% (95% CI: 96.97-100%) and 100% (95% CI: 96.15-100%), respectively. The sensitivity and specificity of IHC was 94.32% (95% CI: 87.24-98.13%) and 100% (95% CI: 93.94-100.0%), respectively. P.G35 mutations were discovered in 2/9 (22.2%) secondary malignant GCTBs and 9/13 (69.2%) GCTB after denosumab treatment. We confirmed in a large series of patients that evaluation of H3-3A mutational status using direct sequencing is a reliable tool for diagnosing GCTB, and it should be incorporated into the diagnostic algorithm. Additionally, we discovered IHC can be used as a screening tool. Proper tissue processing and decalcification are necessary. The presence of the H3-3A mutation did not exclude malignant GCTB. Denosumab did not eradicate the neoplastic cell population of GCTB.

Clinicopathologic and molecular features of denosumab-treated giant cell tumour of bone (GCTB): Analysis of 21 cases.

GCTB is an osteolytic, locally-aggressive, rarely-metastasizing tumour, characterized by abundance of osteoclast-like giant cells, induced by neoplastic mononuclear cells expressing high-levels of the receptor activator of nuclear factor Kappa-B ligand (RANKL), a mediator of osteoclast activation. Although the mainstay of treatment is complete tumour removal with preservation of bone, therapy with denosumab, an inhibitor of RANKL, has been introduced for selected cases. OBJECTIVES: Denosumab-treated GCTB (DT-GCTB) was reported to show a wide spectrum of histological changes such as depletion of osteoclast-like giant cells and intralesional bone deposition, which may lead to diagnostic difficulties. We investigated clinicopathologic and molecular features of DT-GCTB, matched with pre-therapy samples. PARTICIPANTS: 21 cases were included (13 females, 8 males), aged 15 to 64 (median, 30 years). RESULTS: DT-GCTB showed development of sclerotic neocortex and varying degrees of osteosclerosis radiographically. Marked depletion of giant cells, different degree of ossification, fibrosis, and proliferation of mononuclear cells was observed. Staining for H3.3G34W was positive in mononuclear cells in 19 cases (90.5%), while one negative case was positive for H3.3G34V. H3F3A G34W mutation was confirmed in 17 of 19 cases (89.5%), corresponding to nuclear staining with H3.3 G34W antibody. G34L mutation was detected in one G34W negative case, in which H3.3 G34V nuclear positive staining was observed, possibly due to cross-reaction. CONCLUSIONS: Post-therapy tumours still exhibit a similar mutation profile, while significantly differing from classic GCTB morphologically. Correlation with history of denosumab administration, awareness of features of DT-GCTB, IHC and molecular studies for histone H3 mutations are important in its assessment.

Histological and immunohistochemical features and genetic alterations in the malignant progression of giant cell tumor of bone: a possible association with TP53 mutation and loss of H3K27 trimethylation.

In rare cases, giant cell tumor of bone (GCTB) can undergo primary or secondary malignant transformation to malignant giant cell tumor of bone (MGCTB), but the details of the molecular alterations are still unclear. The present study aimed to elucidate the clinicopathologic and molecular features of MGCTBs based on immunohistochemistry, fluorescence in situ hybridization (FISH) and next generation sequencing (NGS) of nine MGCTBs (five primary and four secondary). Seven (78%) of 9 MGCTBs were immunohistochemically positive for H3.3 G34W. In two (22%) patients, although GCTB components were focally or diffusely positive for H3.3 G34W, their malignant components were entirely negative for H3.3 G34W, which was associated with heterozygous loss of H3F3A by FISH. NGS on four MGCTBs revealed pathogenic mutations in TP53 (n = 3), EZH2 (n = 1) and several other genes. Immunohistochemical analysis of the nine MGCTBs confirmed the p53 nuclear accumulation (n = 5) and loss of H3K27me3 expression (n = 3) and showed that they were mutually exclusive. In addition, four (80%) of five cases of pleomorphic or epithelioid cell-predominant MGCTBs were positive for p53, while three (75%) of four cases of spindle cell-predominant MGCTBs were negative for trimethylation at lysine 27 of histone 3 (H3K27me3). The results suggested that p53 alteration and dysfunction of histone methylation as evidenced by H3K27me3 loss may play an important role in the malignant progression of GCTB, and might contribute to the phenotype-genotype correlation in MGCTB. The combined histologic, immunohistochemical and molecular information may be helpful in part for the diagnosis of challenging cases.

Cytodiagnosis of giant cell tumour presenting at unusual age and site with review of literature.

Giant cell tumour (GCT), also known as osteoclastoma, is an osteolytic tumour. It involves the epiphyseal and metaphyseal regions of long bones in adults. On rare occasions, these may occur in paediatric patients, and may involve uncommon locations such as the sternum, pelvis and, particularly infrequently, rib bones. We present a rare case of GCT in the rib of a child, diagnosed on fine needle aspiration.