Differential Diagnosis for Facial Lesions Resembling Melanoma

Single Most Likely Diagnosis

• Melanoma: This is the most likely diagnosis given the description of the lesion resembling melanoma. Melanoma is a serious form of skin cancer that originates in the melanocytes, the cells responsible for skin pigmentation. Its appearance can vary, but it often presents as a new or changing mole.

Other Likely Diagnoses

• Seborrheic Keratosis: These are benign growths that can resemble melanoma due to their pigmentation but are generally more warty in appearance. They are very common and tend to increase with age.
• Dermatofibroma: A benign skin growth that can appear after a minor injury, often resembling a small, hard bump on the skin. While not typically pigmented, some variants can mimic melanoma.
• Basal Cell Carcinoma (BCC): The most common form of skin cancer, BCC can sometimes present with pigmentation, making it a differential for melanoma. However, it typically has a pearly appearance and may ulcerate.

Do Not Miss Diagnoses

• Merkel Cell Carcinoma: A rare and aggressive skin cancer that can resemble melanoma. It grows quickly and can be fatal if not treated promptly, making early diagnosis crucial.
• Squamous Cell Carcinoma (SCC): While SCC is generally less pigmented than melanoma, some variants can have significant pigmentation, making them a "do not miss" diagnosis due to their potential for metastasis.

Rare Diagnoses

• Atypical Fibroxanthoma: A rare skin tumor that can mimic melanoma in its appearance but is generally less aggressive. It tends to occur on sun-damaged skin of older adults.
• Bednar Tumor (Dermatofibrosarcoma protuberans): A rare skin cancer that can have a pigmented variant, making it a differential for melanoma, although it is much less common.
• Blue Nevus: A benign melanocytic lesion that can be mistaken for melanoma due to its deep pigmentation. While benign, its appearance warrants consideration in the differential diagnosis.

Each of these diagnoses has distinct characteristics, but given the initial presentation of a lesion resembling melanoma, a thorough examination, possibly including a biopsy, is necessary to determine the exact nature of the lesion.