Diagnosis of Intraosseous Hibernoma of an Appendicular Skeleton in an Adult – A Rare Case Report

Abstract

Introduction: Hibernoma is an uncommon benign tumor composed of multivacuolated brown adipocytes described in the literature a decade back. Intraosseous hibernomas are extremely rare with propensity to affect axial skeleton. Involvement of appendicular skeleton has been reported only twice in the literature till date. Case Report: We present a case of solitary, painless mass in the left proximal tibia mimicking neoplasm in a 35-year-old male. The plain radiographs revealed a lytic lesion with well-defined margin at the junction of metaphyseal-diaphyseal region of the left proximal tibia. The lesion was hyperintense on T2 and hypointense on T1 with heterogenous enhancement on contrast imaging. FDG-PET showed high uptake of fluorodeoxyglucose. Histopathological examination revealed the presence of multivacuolated cytoplasm with abundant mitochondria suggestive of hibernoma. On immunohistochemistry, the cells were positive for S-100. Conclusion: The findings of imaging modalities are non-specific and histopathological examination is required to confirm the diagnosis of hibernoma. Intraosseous hibernoma needs to be considered as a differential diagnosis of sclerotic bone lesion. Further, evaluation with regular follow-up with imaging will be required if the mass undergoes any clinical changes. Both radiologists and pathologists, need to be aware of this rare entity to avoid misdiagnosis of the uncommon lesion.

Intraosseous hibernoma: clinicopathologic and imaging analysis of 18 cases

“…However, included in this series is the first reported paediatric case in a 7‐year‐old child, while the youngest patient previously reported was 35 31 . The patients in our study showed an almost even distribution between females and males; however, the aggregate of prior investigations has shown a strong female predominance 8–31 . Cancer‐related work‐up/surveillance or pain were the most common indications for imaging, similar to prior reports.…”

“…Compared to prior reports, our median age of diagnosis was slightly older than previous studies (65 versus 57 years). However, included in this series is the first reported paediatric case in a 7‐year‐old child, while the youngest patient previously reported was 35 31 . The patients in our study showed an almost even distribution between females and males; however, the aggregate of prior investigations has shown a strong female predominance 8–31 .…”

“…Further, intraosseous hibernomas have rarely been reported to have reached sizes of at least 9 cm, as reported recently by Srinivasan et al. , 31 which suggests that at least a subset are true neoplasms; therefore, the precise nature of intraosseous hibernomas and their relationship to their soft tissue counterparts remains unclear.…”

“…While one might interpret this as evidence that intraosseous hibernomas do not share common molecular alterations with soft tissue hibernomas, or that intraosseous hibernomas are non-neoplastic, more in-depth molecular analysis is needed before a confident conclusion is drawn. Further, intraosseous hibernomas have rarely been reported to have reached sizes of at least 9 cm, as reported recently by Srinivasan et al, 31 which suggests that at least a subset are true neoplasms; therefore, the precise nature of intraosseous hibernomas and their relationship to their soft tissue counterparts remains unclear.…”

“…Intraosseous hibernomas are rarely documented, usually in the form of case reports or small series, with only 38 cases in the English language literature 8–31 . The relatively small number of reported cases limits our understanding of these tumours.…”