A new look at fibroepithelioma of pinkus: features on confocal microscopy.

Abstract

Fibroepithelioma of Pinkus (FEP) is an uncommon subtype of basal cell carcinoma (BCC) with a distinct growth pattern first described by Hermann Pinkus in 1953 as a premalignant fibroepithelial tumor.1,2 Pinkus noted four such lesions to have a peculiar histologic appearance that resembled both a reticulated seborrheic keratosis and a BCC. These lesions are frequently slow growing and found on the trunk or extremities of individuals between 40 and 60 years of age.3 Clinically, they appear as benign, slowly enlarging, raised or pedunculated solid tumors with a constricted base and of variable color, including shades of pink, yellow, brown, or skin color. They are most commonly found on the trunk or extremities.4–7 Several forms of FEP, including cystic, pleomorphic, eroded, and giant variants have been described. The differential diagnoses include intradermal and compound melanocytic nevi, pedunculated fibroma, fibroepithelial papilloma (acrocordon), granuloma, hemangioma, amelanotic melanoma, neurofibroma, seborreic keratosis, nevus lipomatosus, and nevus sebaceous.3,7 The definitive diagnosis is generally made by histopathology. As variants of BCC, FEP lesions illustrate the interaction and interdependence of stromal and epithelial components in BCC.1 Dermatoscopy and confocal microscopy are noninvasive adjuvant tools that allow the in-vivo evaluation of structures, colors, and patterns in the epidermis, dermoepidermal junction, and the papillary dermis not visible to the naked eye.8 The term dermatoscopy was introduced by German dermatologist Johann Saphier in the 1920s.9 The first Consensus Conference on Skin Surface Microscopy was held in 1989 in Hamburg and the Consensus Net meeting on Dermoscopy was held in Rome in 2001.10 These meetings standardized the definitions of structures seen in benign and malignant pigmented lesions. In the last 10 years, dermatoscopy, also termed epiluminescence microscopy, has opened a new dimension in the examination of pigmented and non-pigmented lesions of the skin.11 Confocal microscopy, first introduced to the scientific community in 195712 uses an image-capturing device that produces in-vivo “optical sections” of an object under observation. This device provides cellular resolution images, which may be used to refine the differential diagnosis of lesions in clinical practice. Both confocal microscopy and dermatoscopy are believed to improve diagnostic accuracy. To our knowledge, the characteristics of FEP as seen on confocal microscopy have not been described. We present a patient with FEP, which clinically resembled an intradermal nevus. The presence of dermatoscopic and confocal features assisted in the diagnosis, which was subsequently confirmed by histopathology.