A huge left buttock mass in an old female.

INTRODUCTION: Myxofibrosarcoma also known as myxoid malignant fibrous histiocytoma is a rare soft tissue sarcoma that has a predilection for the elderly (beyond the 6th decade).

CLINICAL OBSERVATION: We report a case of a 64 years old patient that presented gradual appearance of huge tumor on her left buttock. Radiologic examination (MRI) concluded to MFS. There was no evidence of systemic involvement. The patient was directed in an oncology center, where the diagnostis of MFS was confirmed through surgical biopsy.

DISCUSSION: MFS is one of the most frequent sarcoma of soft tissue that occurs in elderly patients. This is an infiltrant tumor that is extending through muscular fascia. MRI is the gold standard in characterisation; it makes the positive diagnosis of MFS thanks to the myxoid signal, triple signal and the tail sign that is corresponding to the extension of the tumor into the muscular fascia and peri nervous spaces.

CONCLUSION: Cross-sectionnal imaging in particular MRI plays a key role in the positive diagnosis of soft tissue tumors. It makes possible to approach with great precision the exact nature of the tumor thanks to specific radiological semiology without however claiming to replace histology.