A rare case of clear cell sarcoma of the foot with a cascade of pathological misdiagnosis—the importance of expert sarcoma pathology

摘要

Sarcoma pathology discrepancy is well known owing to the extremely heterogenous and rare nature of this tumour. Through this case, we want to highlight the difficulty that a patient has to undergo in a case of misdiagnosis. A 20-year-old male presented with swelling in the right foot for 4 months, which was initially diagnosed as alveolar rhabdomyosarcoma, subsequently as synovial sarcoma and finally as Ewing’s sarcoma (based upon positive Ewing Sarcoma Breakpoint Region 1 (EWSR1) by fluorescence in situ hybridisation and he underwent neoadjuvant chemotherapy and surgical excision with grafting before he presented to our institute, where the pathologists reviewed the biopsy slides, which were positive for HMB45 and negative for Melan-A suggestive of clear cell sarcoma. The next-generation sequencing suggested EWSR1-ATF1 fusion, which again reinforced the diagnosis. This case throws light on the importance of expert pathology and interpreting molecular results in the right context.