melanocytic

Melanocytic is an adjective referring to melanocytes, the pigment-producing cells located primarily in the skin but also in the eyes, mucous membranes, and certain other tissues. Melanocytes synthesize melanin, the pigment that determines color and provides some protection against ultraviolet radiation. They originate from neural crest cells and reside in the epidermal basal layer, in hair follicles, and in other pigment-bearing sites such as the uveal tract of the eye.

Melanocytic activity influences human coloration and photoprotection. Melanin production is controlled by enzymes including tyrosinase and is modulated by genetics, sun exposure, and hormonal factors. The pigment is transferred from melanocytes to neighboring keratinocytes in the epidermis, forming visible skin color.

Clinical relevance: Melanocytic lesions include benign nevi (moles), which are clusters of melanocytes at the dermal-epidermal junction or in the dermis. Dysplastic nevi show architectural and cytologic atypia and may carry a higher risk of progressing to melanoma. Melanoma is a malignant tumor of melanocytes and is the most serious pigmented skin cancer; prognosis depends on thickness, ulceration, location, and molecular features. Management typically involves excision and, depending on stage, systemic therapy.

Pathology and diagnostics: Immunohistochemical markers such as S-100 protein, HMB-45 (gp100), Melan-A/MART-1, and MITF are used to identify melanocytic lineage in tissue samples. In the eye and other sites, melanocytic tumors can occur (e.g., uveal melanoma).

Overall, melanocytic describes anything related to melanocytes, their pigment production, and the spectrum of benign and malignant lesions arising from them.