Leiomyoadenomatoid Tumor of Epididymis: A Variant of Adenomatoid Tumor

Abstract

Adenomatoid tumor is a rare tumor of mesothelial origin, usually arising in the epididymis. It is the most common paratesticular tumor of middle-aged men. A rare variant of adenomatoid tumor is leiomyoadenomatoid tumor which is characterized by prominent spindle cell myoblastic and myofibroblastic proliferation in the background of an adenomatoid tumor with tubular spaces lined by mesothelial cells. In some cases, the spindle cell component obscures the adenomatoid tumor component, complicating accurate diagnosis. Here, we report two cases of paratesticular leiomyoadenomatoid tumor in 28-year-old and 50-year-old patients. The tumors from both cases were centered in the epididymis and measured 1.0 cm and 3.0 cm, respectively. Both had similar morphology with myofibroblastic proliferation in one case and myoblastic (smooth muscle) proliferation in the other. Both cases followed a benign course without local recurrence or distant metastasis for 14 and 22 months postoperatively, respectively. We propose the use of the term "adenomyomatoid tumor" to describe a neoplasm exhibiting adenomatoid tumor admixed with either leiomyomatous or myofibroblastic proliferation.

Keywords: adenomatoid tumor; immunohistochemistry; leiomyoadenomatoid tumor; myoblast; myofibroblast; paratesticular.