Case of Rare follicular variant of Becker's nevus reported

An 18‑year‑old man presented with multiple asymptomatic well‑defined, folliculocentric macules tending to coalesce at one side over the right chest and supraclavicular area since 1.5 years which was gradually progressive in nature. There was no history of seizures, developmental delay or any other neurological complaints associated with the lesion. The patch had terminal hair in at the centre of each hyperpigmented macule without any skin thickening or nodularity. There was no evidence of limb or breast hypoplasia or asymmetry.

Dermoscopy (Dermlite DL200 Hybrid M; polarized mode) showed a well‑defined network‑like pigmentation with immediate perifollicular hypopigmentation and well‑defined areas of darker pigment network surrounding these areas. Histopathology demonstrated hyperpigmentation of the basal layer and regular acanthosis with no evidence of dermal smooth muscle proliferation. Thus, a final diagnosis of follicular Becker's nevus was made. The patient was counselled about the nature of the condition and advised treatment with Q‑switched ND-YAG laser in higher centres.

Becker's nevus is a cutaneous hamartoma exact etiology of which is unknown. Beta‑actin (ACTB) mutations amplify Hedgehog signaling leading to interference with the development of hair follicles and arrector pili muscles explaining perifollicular arrangement of macules. Androgens play a role in this condition as seen by peri‑pubertal development, hypertrichosis, acneiform lesions in the involved area, and hypertrichosis, with an increase in androgen receptors in the involved skin noted.

Several morphological variants of Becker's nevus have been reported including the presence of only pigmentation (Becker' melanosis), giant Becker's nevus, blaschkoid Becker's nevus, bilateral involvement, and presence of multiple lesions. Becker's nevus syndrome is an association of Becker's nevus with unilateral breast hypoplasia and muscle, skin, and/or skeletal abnormalities.

It is suggested by the authors that the presence of folliculocentric macules points to an causative role of the follicular epithelium. In contrast to the dermoscopy of classical Becker's nevus in which a continuous sheet of pigmentation is seen, islands of pigmentation are seen in the case of follicular Becker's nevus. It can often pose a diagnostic conundrum, being misdiagnosed as pityriasis versicolor.

To conclude it is of importance that follicular variant of Becker's nevus is rare but can present as early and evolving lesions of Becker's nevus and lack of scaling and unilateral location along with the dermoscopic findings can help differentiate the lesion from pityriasis versicolor.

Source- Ranglani H, Malakar S. Clinical and Dermoscopic Features of Follicular Becker's Nevus: A Rare Variant. Indian Dermatol Online J. 2021 Aug 21;12(5):750-751. doi: 10.4103/idoj.IDOJ_877_20. PMID: 34667764; PMCID: PMC8456253.