The Diagnosis: Fibroepithelioma of Pinkus
Fibroepithelioma of Pinkus (FeP) was first described in 19531 and was thought to be premalignant as evidenced by the proposed name premalignant fibroepithelial tumor of the skin. This neoplasm now is largely believed to represent a rare form of basal cell carcinoma (BCC). Typical presentation is a smooth, flesh-colored or pink plaque or nodule.2 Fibroepithelioma of Pinkus has a predilection for the lumbosacral back, though the groin also has been reported as a common site of incidence.1,3 Similar to other BCCs, it is seen in older individuals, typically those older than 50 years.3,4
Clinical diagnosis of FeP can be difficult. The differential diagnosis of FeP can include acrochordon, amelanotic melanoma, compound nevus, hemangioma, neurofibroma, nevus sebaceous, pyogenic granuloma, and seborrheic keratosis.5 Dermoscopic evaluation can aid in the diagnosis. A vascular network composed of fine arborizing vessels with or without dotted vessels and white streaks are characteristic findings of FeP. Patients with pigment also demonstrate structureless gray-brown areas and gray-blue dots.6
Biopsy with subsequent histopathologic evaluation confirms the diagnosis of FeP. The characteristic microscopic findings of thin eosinophilic epithelial strands with eccrine ducts anastomosing in an abundant fibromyxoid stroma with collections of basophilic cells located at the ends of the epithelial strands were demonstrated in our patient’s histopathologic specimen (Figure). The histologic appearance is similar to syringofibroadenoma of Mascaro. Recognition of basaloid nests, which often demonstrate retraction, and mitotic activity can differentiate FeP from syringofibroadenoma of Mascaro.7
Anastomosing eosinophilic epithelial strands in a fibromyxoid stroma (A)(H&E, original magnification ×20). Basophilic cells at the ends of the eosinophilic strands with occasional eccrine ducts (B)(H&E, original magnification ×40).
Treatment of FeP is largely the same as other BCCs including destruction by electrodesiccation and curettage or complete removal by surgical excision. Several studies have demonstrated effective treatment of nonaggressive BCCs with curettage alone and subjectively reported improved cosmesis compared to electrodesiccation and curettage.8-10 Although methyl aminolevulinate photodynamic therapy has demonstrated some therapeutic efficacy for superficial and nodular BCCs,11 a case report utilizing the same modality for FeP did not provide adequate response.12 However, adequate data are not available to assess potential use of this less invasive therapy.