Abstract
Epithelioid leiomyomas are uncommon tumors which are found almost exclusively in the gastrointestinal tract or the uterus. We report a case of epithelioid leiomyoma found in the muscles of the neck (m. sternocleido-mastoideus) in a sixteen-year-old boy. Histologically, the tumor cells were composed of round cells (epithelioid cells) and plump-spindle cells forming fascicles. The epithelioid cell showed eosinophilic cytoplasm and vesicular nuclei. The ultrastructural findings revealed the characteristics of smooth muscle cells, such as subplasmalemmal dense patch, cytoplasmic dense bodies, cytoplasmic microfilaments, pinocytotic vesicles, and basal lamina.
