P. Treadwell et al. (eds.)Atlas of Adolescent Dermatologyhttps://doi.org/10.1007/978-3-030-58634-8_24

24. Pilomatrixoma

Patricia Treadwell¹

(1)

Department of Dermatology, Indiana University School of Medicine, Indianapolis, IN, USA

Patricia Treadwell

Email: ptreadwe@iupui.edu

Keywords

PilomatrixomaAdnexal tumorHair follicle matrix

24.1 Introduction

Pilomatrixoma is a benign adnexal tumor. It is also known as a calcifying epithelioma of Malherbe. It consists of benign hyperplasia of the hair follicle matrix cells.

24.2 Epidemiology

Pilomatrixomas may occur at any age; nonetheless, they most often are noted prior to age 20. Generally, these lesions do not have a known genetic predisposition; however, multiple lesions have been associated with myotonic dystrophy, Gardner syndrome, Rubenstein-Taybi syndrome, and trisomy 9 (among others) . Some recent studies have identified an association with mutations in Wnt (wingless and Int-1) signaling pathways [1].

24.3 Clinical Findings

Pilomatrixomas are typically solitary nodule and noted most often on the face or proximal extremities. The lesions tend to be slow growing, firm lesions with an irregular surface (Fig. 24.1). Some of the lesions will have a violaceous discoloration initially. Pilomatrixomas may develop calcium deposits and become very hard.

../images/446896_1_En_24_Chapter/446896_1_En_24_Fig1_HTML.jpg — Fig. 24.1
Irregular surface of this pilomatrixoma below the medial eyebrow

24.4 Laboratory

When a biopsy is performed, the findings are proliferation of basaloid cells, shadow cells, or both [1].

24.5 Treatment

The lesions will sometimes resolve spontaneously over a period of several months. If they become repeatedly flared or superinfected, they can be surgically excised.

24.6 Prognosis

When the lesions resolve spontaneously, minimal scarring is noted. When they are surgically excised, a healed surgical scar will result.