Blue Nevus with a Dermoscopic Appearance of Peripheral Streaks with Branches
A 46-year-old Japanese woman came to us with an asymptomatic pigmented plaque on her left arm. The patient did not remember its onset. She was otherwise healthy. A physical examination revealed an asymptomatic blue-blackish plaque 2 mm in size on the left upper extremity (fig. ). Dermoscopy showed a central homogeneous dark blue-black pigmentation and peripheral blue-brownish streaks with branches (arrow) (fig. ). We performed a whole excision as biopsy, because we suspected the plaque to be a malignant melanoma. The specimen from the central lesion showed spindle cells with melanin pigments in the upper dermis, but not in the epidermis (fig. ). A deep section of the peripheral lesion identified focally aggregated and isolated spindle cells with melanin pigments in the upper dermis (fig. ).\nWith the deep sections, we confirmed that the dermal dendritic melanocytes were distributed in the direction of the streaks. Using dermoscopy, we confirmed peripheral branching streaks and diagnosed the blue-blackish plaque as blue nevus with histopathologic assessment.