An Unexpected Giant: A Case of Massive Paratesticular Extra-mammary Myofibroblastoma.

Mammary-type myofibroblastomas (MFBs) are benign spindle cell tumors, typically presenting in common locations such as the breast, abdomen, and inguinal region. We present a case of a 66-year-old male with a four-year history of painless scrotal swelling. The preoperative diagnosis was challenging, with an initial suspicion of soft tissue sarcoma. A complete surgical excision was performed, revealing a well-circumscribed, encapsulated mass. The tumor measured 30 x 20 x 14 cm, weighing 5.28 kg. Histopathology confirmed an MFB. This exceptionally large paratesticular MFB emphasizes the diagnostic difficulty of such tumors. Surgical resection remains the treatment of choice, with an excellent prognosis. This case highlights the importance of considering MFB in the differential diagnosis of scrotal masses, even with atypical presentations.