Low-grade chondrosarcoma vs enchondroma: challenges in diagnosis and management

A 28-year-old man presented with a swelling at the right thoracic wall. Com puted tomography showed an aggressive process involving the cortex of the r ib with concomitant soft tissue mass. However, a needle biopsy specimen rev ealed an enchondroma and consequently the physician decided to apply a "wai t-and-see" strategy. After 3 years of careful follow-up by MR imaging, the patient complained of subtle enlargement of the lesion, which was later con firmed on repeated CT scan. Despite an aggressive appearance on control MR imaging, histopathological examination after incisional biopsy could not di fferentiate between enchondroma and low-grade chondrosarcoma. Wide excision including previous biopsy trajectory was performed. Diagnosis of a low-gra de (grade I) chondrosarcoma was made on findings of the excisional specimen and seeding of cartilage tissue along the previous incisional biopsy traje ctory was found.