Nevus comedonicus

Abstract

The nevus comedonicus (NC) is an uncommon variant of adnexal hamartoma which appears clinically as linear groups of open comedones. Its name may be a misnomer since, according to some, true comedones are not present. NC usually occurs by itself but may be linked with a variety of systemic findings such as skeletal or ocular anomalies. Although the nevus comedonicus is viewed by many as a hamartoma arising from a defective mesoderm, others consider this lesion to be an epidermal nevus involving the hair follicle or an appendageal nevus of sweat ducts.

Role of FGFR2-signaling in the pathogenesis of acne

“…141 Nevus comedonicus appears clinically as linear groups of open comedones presenting confluent clusters of dilated follicular orifices plugged with keratin. About 50% of cases are evident at birth, with the other 50% developing before the age of 10 years.…”

Update on Epidermal Nevi and Associated Syndromes

“…Lesions may be extensive unilaterally [29]. NC has a predilection for the face, neck, trunk, and proximal extremities [31]. Inflammatory variants can occur, with recurrent pustules, cysts, and secondary bacterial infections.…”

“…Despite comedonelike appearance of the lesion, appearance of NC is not altered by hormonal variations, such as menarche, menopause, or pregnancy [35]. It has been hypothesized that NC arises from a developmental defect in the mesodermal component of the pilosebaceous unit, wherein the resulting follicular structure is only able to produce soft keratin, which then accumulates [31]. One study found increased filaggrin expression in closed comedones of NC but found no differences in cytokeratin expression between NC and normal skin [36].…”

“…Histopathology of NC reveals epidermal invaginations resembling dilated hair follicles filled with lamellar keratin [31,35]. EHK has been described in the keratinocytes of the follicular epithelial wall in NC and therefore may represent mutations in keratins 1 and 10 [38,39].…”

“…Surgical excision is the definitive treatment and, as such, extensive lesions can be challenging to treat. Topical therapies, such as ammonium lactate and other keratolytics, retinoids, calcipotriene, or tacalcitol, have been variably effective [30,31,41,42]. Oral antibiotics or intralesional corticosteroids may be effective for the inflammatory variant [32,35].…”