Coexistence of Giant Blue Nevus of the Scalp with Hair Loss and Alopecia Areata

A 43-year-old Japanese man exhibited a giant blue nevus on his scalp, characterized by a 7 cm grayish macule with sparse hair, present for 13 years. Histopathological analysis revealed spindle-shaped and ovoid melanocytes with abundant melanin around the pilosebaceous apparatus and fibrous collagen bundles around small hair follicles. This led to a diagnosis of a cellular type blue nevus. Such nevi are rare on the scalp, with only 11 cases reported, and are known for causing hair loss and potential cranial invasion. The melanocytes in these nevi can damage underlying structures, including bone and hair follicles. Additionally, the patient had alopecia areata on the left temporal area, which responded well to topical corticosteroid treatment.