A 55-year-old presents to the clinic with a changing mole on her back that she first noticed three months ago. She states it has grown in size since she first noticed it, and it recently started to itch. She reports a history of multiple sunburns in the past, and past medical history is otherwise negative. Vital signs are within normal limits. Physical examination reveals a fair-skinned woman with a mole on the back that is 8 mm in diameter and asymmetric, with irregular borders, and variegated color.
C) Melanoma
The ABCDE rule is a tool used to identify suspicious pigmented lesions that may represent melanoma.
Asymmetry means one half of the lesion does not mirror the other.
Border irregularity occurs when the edges are ragged, notched, or poorly defined.
Color variation may include multiple shades such as brown, black, red, white, or blue within the same lesion.
Diameter greater than 6mm increases the risk of a lesion being melanoma.
Evolution is considered the most important feature and means any change in size, shape, color, or associated symptoms like itching or bleeding.
Cutaneous melanoma arises from melanocytes, with risk factors including age (peak 50-60 years), female gender, fair skin, ultraviolet exposure, and family history (e.g., CDKN2A mutations).
Answer choice A: Basal cell carcinoma, is incorrect. Basal cell carcinoma is a pearly nodule that is slow growing and related to ultraviolet exposure, but the description of this mole is more consistent with melanoma.
Answer choice B: Dermatofibrosarcoma protuberans, is incorrect. Dermatofibrosarcoma protuberans is a rare, slow-growing skin cancer that starts in the dermis and forms a firm, reddish-purple or flesh-colored patch or nodule. It often appears on the trunk and can resemble a scar.
Answer choice D: Merkel cell carcinoma, is incorrect. Merkel cell carcinoma is a rare-aggressive skin cancer that forms in Merkel cells, which are neuroendocrine cells in the skin’s top layer. It often appears as a fast-growing, painless flesh-colored or reddish lump on sun-exposed skin, especially of the head and neck.
Answer choice E: Squamous cell carcinoma, is incorrect. Squamous cell carcinoma is hyperkeratotic lesion often appearing as a red, scaly patch, firm bump, or wart-like sore, especially in sun-exposed areas like the face, ears, hands, and scalp. It is primarily caused by ultraviolet radiation.
Key Learning Point
Melanoma risk factors include age, fair skin, UV exposure, and genetics. The ABCDE criteria can be used to help differentiate a melanoma from a benign nevus.
