Mucinous Nevus

Abstract

Mucinous nevus is an uncommon entity classified as either a cutaneous mucinosis or a connective tissue nevus. The condition presents as grouped papules and coalescent plaques growing in a unilateral or zosteriform manner. The key histopathological feature is a band-like deposition of mucin in the superficial dermis. A 34-year-old male presented with grouped gray-brown papules and confluent plaques exhibiting a zosteriform distribution on the right side of the lower back. The lesions had commenced in childhood. Histological examination revealed mucin deposition in the papillary dermis. Thus, we diagnosed a mucinous nevus. To date, only a few reports of such nevi have been reported in the literature. Therefore we report a rare case of mucinous nevus.

Keywords: Cutaneous; Mucin; Nevus.

Fig. 1. (A) Multiple gray-brownish papules and confluent plaques with a zosteriform distribution on the right lower back. (B) Close-up view.

Fig. 2. (A) Amorphous materials and loosely separated collagen fibers in the papillary dermis and acanthosis with elongated rete ridges (H&E, ×40). (B) Positively stained bluish amorphous materials in the papillary dermis (Alcian blue at pH 2.5, ×40). (C) Reduced numbers of elastic fibers in the papillary dermis bearing mucin deposits (Verhoeff-van Gieson, ×40).