Becker’s Nevus on Face Misdiagnosed as Whiskers

Introduction

Becker’s nevus (BN), whose additional name was pigmented hairy epidermal nevus, was originally described by Samuel William Becker in 1949.¹ BN is a kind of epidermal cutaneous hamartoma,² which can be present at birth or appear in early childhood, but they mostly occur around puberty. A noticeable hyperpigmented patch with a big, unilateral, hyperpigmented macule and irregularly shaped borders is the manner in which BN often presents. Males are more likely to develop this type of nevus than females, which typically occurs on the upper trunk and shoulders. Occasionally, it could appear in unusual locations like the forehead, cheek, eyelids, neck, abdomen, hips, and so on.^2–4 Hypertrichosis is another manifestation but does not occur so prevalently.⁵ In our clinic, we found this case of BN with apparent hypertrichosis on one side of the cheek rather than in common areas, which made it challenging to make a differential diagnosis with whiskers.

Case Report

A 16-year-old boy has asymptomatic dark brown colored follicular macule on the left side of the cheek shortly after birth. The lesions were initially inconspicuous but gradually became darker as time passed. The macules on some of them grew hair. Cutaneous examination exhibited a continuous area of brownish perifollicular macules with hypertrichosis on the left cheek as opposed to the same location on the other side of the face (Figure 1). Before this visit, he had been diagnosed with whiskers at a local hospital. The patient did not consent to undergo histological examination. Becker’s nevus syndrome (BNS) is a syndrome that presents not only Becker’s nevus but also other extracutaneous symptoms such as musculoskeletal abnormalities and ipsilateral breast hypoplasia. We examined the patient for these extracutaneous symptoms, but found no abnormalities. These findings corresponded to BN.

Figure 1 (A) the normal side of the right cheek. (B) a continuous area of brownish perifollicular macules with hypertrichosis on the left cheek.

Discussion

In spite of being relatively rare, BN that develops on the face still exists in clinical. It was challenging for dermatology residents to differentiate BN mentioned in this report from typical whiskers due to the apparent hypertrichosis on the cheek. Kiliç et al and Polat et al respectively reported a case of BN with asymmetrical beard hair growth. These two patients were easily misdiagnosed as whiskers because of their long beard.^3,6 The primary point of differentiation is that the lesions of BN only appear unilaterally. On the other hand, the face has whiskers on both sides. Additionally, BN will show hyperpigmentation whereas whiskers do not.

The epidermis of histology of BN exhibits acanthosis, papillomatosis, and hyperpigmentation, while the erector pili muscle exhibits hyperplasia, and the dermis exhibits melanophages.⁶ Unfortunately, the patient enrolled in this report did not have a histologic examination. The etiology of BN is still unclear. It is considered to be an abnormality of epidermal-dermal interaction that may be exacerbated by hormone-influencing factors, particularly androgen, as BN more frequently affects males and commonly develops or aggravates around the age of puberty.⁷

Conclusion

In conclusion, for its unusual clinical presentation, we believe that reporting this case may help dermatologists avoid misdiagnosing similar cases.