Clinical pathologic conference case 1: a woman with a lump in her cheek

Pilomatrixoma of the right thigh: Sonographic-pathologic correlation in a young man

Pilomatrixoma, also known as calcifying epithelioma of Malherbe, is a histological type of benign subcutaneous tumor arising from the cutaneous adnexa. We present our experience and the characteristic findings of a pilomatrixoma of the right thigh in a young healthy man. The lesion had grown slowly in size over the past year and this was the reason for referral to the Department of Plastic Surgery. Ultrasound imaging was performed and, through the use of B-mode, color-Doppler, and elastosonography, the lesion was depicted. The patient was therefore scheduled for surgery.

Pilomatrixomas at times can pose a diagnostic challenge, especially when the location is unusual. Ultrasound and its tools, that is, color-Doppler and elastography, can assist the clinician arising the suspicion of pilomatrixoma.

Pilomatrixoma: A Comprehensive Review of the Literature

INTRODUCTION

Pilomatrixoma, also known as calcifying epithelioma of Malherbe, is a superficial benign skin tumor that arises from hair follicle matrix cells. Although pilomatrixomas are well-recognized lesions, clinically they are frequently misdiagnosed as other skin conditions. By reviewing all the literature over the past 10 years, the aims of this article are to analyze the cause, clinical presentation, management, and outcome of pilomatrixoma among children and adults to gain a more complete understanding of this lesion in today's clinical context.

METHODS

A MEDLINE and EMBASE search was conducted from January 2005 to February 2015 using a combination of the terms: "child," "childhood," "adult," and keywords: "pilomatrixoma," "pilomatricoma," and "calcifying epithelioma of Malherbe." A total of 150 articles were reviewed.

RESULTS

The lesions occurred most commonly in the first and second decades (mean age 16 years and 7 months). The commonest presentation was of an asymptomatic, firm, slowly growing, mobile nodule. Only 16% were accurately diagnosed on clinical examination. Imaging in the form of ultrasound, computed tomography, and magnetic resonance imaging has been reported. Pathological diagnosis was achieved through incision, punch, and shave biopsies. Pathological findings are discussed and summarized in this review.

CONCLUSION

Pilomatrixomas are thought to arise from mutation in the Wnt pathway and has been linked to several genetic conditions. It is commonly misdiagnosed preoperatively; however, with better awareness of the lesion, it can be appropriately treated while avoiding unnecessary diagnostic tests. Complete surgical excision with clear margins is almost always curative.