Histologic Variants of Fibrous Papule

Abstract

Fibrous papule (FP), synonymous with angiofibroma, is a common lesion that is often biopsied to exclude carcinoma. Clinically, FPs are small, dome‐shaped, solitary, flesh colored papules arising on the nose and face of adults. Histologically, FPs are characterized by a dome‐shape, fibrotic collagenized stroma, sparse inflammatory cell infiltrate, and variably increased and dilated vascular spaces. The vast majority of FPs are readily diagnosable based on these clinical and histologic criteria. Rare histopathologic variants have been reported. Recognition of these variants may avoid misdiagnosis of this common benign lesion. We illustrate four rare variants of FP that can cause diagnostic uncertainty including: hypercellular, clear cell, pigmented, and pleomorphic variants. Cellular FP has a dense infiltrate of round fibroblasts that have a nevoid appearance. Clear cell FP has a proliferation of round clear cells, some with slightly foamy cytoplasm, resembling histiocytes or clear epithelial cells. Pleomorphic FP demonstrates bizarre, stellate fibroblasts like those seen in pleomorphic fibroma. Pigmented FP has prominent melanocytic hyperplasia and dermal melanophages that can be confused with a melanocytic lesion. It is important to recognize these unusual variants of FP in order to accurately diagnose this common benign lesion and avoid over treatment or rebiopsy.