성인에서 발생한 근섬유형 혈관주위근종

초록

Myofibromatosis is a rare but well recognized entity which was considered to arise exclusively in neonates and infants and is extremely rare in adults. Recently, adult myofibromatosis, glomangiopericytoma and myopericytoma were categorized as a perivascular myoma.We report a case of myofibromatosis type perivascular myoma arising in an adult patient. A 47-year-old man was admitted to our hospital because of palpable masswhich was slowly growing for 6 years in the right knee. He had medical history of three times of operation due to colon cancer, stomach cancer and testicular seminoma several years ago and underwent radiotherapy. The tumor was located in the subcutaneous tissue and measured 1.2x1cm. It was well circumscribed but not encapsulated. Histologically, it showed a biphasic pattern that consisted of fascicles of spindle cells with abundant eosinophilic cytoplasms that resembled smooth muscle surrounding thin and thick walled vessels,in addition to a population of more cellular areas of primitive small, ovoid to spindled cells with scant cytoplasm, focally associated with hemangiopericytoma-like vascular pattern. The arrangement of the two components was a pattern of reverse zonation. The tumor cells were diffusely immunoreactive for smooth muscle actin and vimentin, focally positive for desmin in the spindle cell myoid area, but not reactive for S-100 protein, CD34 and CD 68. This tumor showed characteristic histologicfeature which enable to be distinguished from other fibrous lesions and from benign or malignant smooth muscle tumors.