Follicular Becker's Nevus: A Case Report of an Uncommon Clinical Variant

Abstract

Pigmented hairy epidermal nevus, also known as Becker's nevus, has a typical description as a unilateral, hairy in appearance, light to dark brown patch with an irregular but clearly defined border. However, the exact aetiopathogenesis is still poorly comprehended. We report the case of a 19-year-old female who presented with asymptomatic brownish-pigmented macular lesions on the right breast that had slowly increased in size over the past three years. Upon cutaneous inspection, the right breast had 3-5 mm rounded and oval perifollicular macules that ranged from light to dark brown hue without increased hair growth. The macules were discrete and in no particular pattern. Dermoscopy of the lesions showed well-defined perifollicular hypopigmentation surrounded by a pigmented network-like pattern. Histopathology of a punch biopsy taken from one of the follicular lesions demonstrated an increase in basal layer pigmentation with elongation of rete ridges and acanthosis, consistent with Becker's nevus. The patient underwent three sittings of diode laser therapy, once in four weeks, with slight improvement in pigmentation.

Keywords: becker’s nevus; dermoscopy; hypopigmentation; macular lesions; perifollicular.

Figure 1. a) Numerous, hyperpigmented, follicular macules are seen on all four quadrants of the right breast. b) Exclusive involvement of the right breast with hyperpigmented macules in all four quadrants and relative sparing of the left breast

Figure 2. Dermoscopy (DermLite DL4) findings are a) islands of well-defined dark pigment network (violet arrows), interspersed between these islands are areas of normal skin with a normal skin pigment network (yellow arrows), and b) each individual follicle shows immediate perifollicular hypopigmentation (red arrows) surrounded by a hyperpigmented zone (blue arrows), which corresponds clinically to hyperpigmented macules representing follicular variant of Becker's nevus

Figure 3. Histopathological features are a (H&E ×100) and b (H&E ×400): skin with epidermis showing focal mild hyperpigmentation of basal keratinocytes with the superficial dermis showing minimal perivascular lymphoplasmacytic infiltrates. c) (H&E ×400) The deep dermis and sweat glands appearing unremarkable