Combined Epidermal-Follicular Mucinous Nevus: Dermoscopic Appearance.

Case Presentation

A 17-year-old Hispanic male presented with long-standing asymptomatic papules grouped as an irregular, brown, 10 cm × 6 cm × 0.2 cm plaque over the right aspect of the neck (Figure 1A). Perifollicular hypopigmentation and geometric brown structures were observed on dermoscopy (Figure 1B). Epidermal hyperkeratosis, acanthosis, papillomatosis, as well as abundant mucin deposits around the hair follicles were noted on histopathology, compatible with combined epidermal-follicular mucinous nevus (MN).

Figure 1

Combined epidermal-follicular mucinous nevus. (A) Clinical appearance. (B) Perifollicular hypopigmentation and pigmented geometric structures around the papules can be observed on dermoscopy.

Teaching Point

There are less than 30 reports of MN in the literature [1]. Histopathology is essential for the diagnosis, wherein mucin deposits along the superficial dermis are present. The combined epidermal subtype also exhibits hyperkeratosis, acanthosis, and rete ridges elongation. Perifollicular mucinous involvement has only been described in one case, yet epidermal changes were subtle [2]. In contrast, we observed epidermal changes and perifollicular mucin deposits, which correlated with perifollicular hypopigmentation observed in dermoscopy. The dermoscopic appearance of MN has not been previously documented.