Which is a malignant neoplasm originating in the skin?

Melanoma is a malignant neoplasm of melanocytes, which are pigment-producing cells found primarily in the skin. It is one of the most serious forms of skin cancer and is classified under ICD-10-CM category C43.- (Malignant melanoma of skin).

Osteosarcoma is a malignant tumor of bone, not skin (ICD-10-CM C40–C41).

Hemangioma is a benign tumor of blood vessels and is not malignant (often coded under D18.-).

Lymphoma is a malignancy of the lymphatic system, not a primary skin neoplasm (ICD-10-CM C81–C85), though rare cutaneous lymphomas exist, they are not the standard CPC exam answer here.