Abstract

A 20-year-old female presented with a tan-red, dome-shaped 5 mm asymptomatic slowly growing papule on the nose present for one year. The clinical decision by plastic surgery was to excise the lesion. Upon histopathologic examination, a well-circumscribed dermal lesion was present immediately subjacent to the epdermis measuring 2mm in greatest horizontal dimension and 1mm in greatest vertical dimenstion. The tumor consistent of epithelioid and fusiform cells with significant nuclear pleormophism, nuclei with vesicular chromatin and pinpoint nucleoli, and abundant pale grey cytoplasm without pigment deposition. Collagenous stroma was interspersed between the tumor cells and admixed mature lymphocytes were present. No mitotic figures or necrosis was present. Immunohistochemical evaluation showed that the tumor cells were negative for Keratin AE1/AE3, S100, Mart1, Sox10, desmin, CD34, CD68, CD163, factor XIIIA, and podoplanin. Based on the histomorphology and negative immunohistochemical work-up, a diagnosis of an inflamed pleomorphic fibroma (PF) was rendered. First described by Kamino et al in 1989, PF is a rare entity that appears benign clinically, but histopathologically characterized by cells with significant nuclear pleormorphism without mitoses that can be mistaken for a malignancy. It presents as a flesh-colored papule or nodule in adults with no anatomic preference. The histogenesis is uncertain, but may be of myofibroblastic or dermal dendritic cell origin. The tumor cells are often CD34 positive often with focal staining and negative staining at times. Factor XIIIa staining may be seen. The tumors follow a benign course, but may be locally recurrent.

Financial Disclosure:
No current or relevant financial relationships exist.