Fig. 2
From: Myofibroma of the pinna: a case report and review of the literature
Histopathology of the left ear lesion at A 4×, B 10×, and C 20× magnification. Bland spindle cell and fibrous lesion, suggestive of myofibroma. Microscopic examination reveals a poorly demarcated and low- to moderately-cellular spindle cell and fibrous lesion. Spindle cells are arranged in intersecting and whorled fascicles and appear to entrap adipose tissue and associated skin adnexal structures, but there is no evidence of cytologic atypia or increased mitotic activity. The fibrous stroma is variably sclerotic and focal keloidal type collagen is apparent. Intervening vascular structures including angulated capillary forms and relatively larger and thick-walled arteries are identified; there is patchy vascular congestion, but no red blood cell extravasation is appreciated. D By immunoperoxidase staining methods, the spindle cells show patchy weak positivity for SMA indicating myofibroblastic differentiation. A CD34 stain (not shown) is negative in the spindle cells and highlights the component vasculature. The cells are negative for nuclear expression of beta-catenin