A diagnosis of skin cancer requires a physical examination, a biopsy, and laboratory tests. The diagnosis usually includes an assessment of the stage of cancer present. Skin cancer can be local or metastatic. Self-examination often detects skin cancer in very early stages.
A physician or dermatologist examines the patient’s skin for irregular-looking areas when looking for a diagnosis of skin cancer. This type of cancer appears most often on sun-exposed areas, such as the face, scalp, neck, and shoulders. The arms and chest are also typical areas for skin cancer. Sometimes skin cancers appear in hidden areas, especially in people with dark skin. Skin cancer can even occur under the fingernails, the palms of the hands, or soles of the feet.
The three most common types of skin cancer are basal cell carcinoma, squamous cell carcinoma, and melanoma. Less common skin cancers include Merkle cell carcinoma, sebaceous gland carcinoma, and Karposi sarcoma. Basal cell carcinoma and squamous cell carcinoma rarely go beyond the local stage of cancer, but melanoma has a high likelihood of metastasizing. The local type of skin cancer remains in one area, usually as a bump or lesion. A diagnosis of skin cancer in a localized stage is typically found through a simple biopsy of the suspected skin area; a laboratory test is usually required to confirm the diagnosis.
Diagnosing metastatic cancer involves more intensive testing. Two types of biopsy, fine needle aspiration or surgical lymph, can sample nearby lymph nodes to determine whether skin cancer cells have moved from the skin to the lymphatic system. Sentinel lymphatic mapping can help determine the specific lymph node most likely to be infiltrated.
Imaging systems such as magnetic resonance imaging (MRI), computed tomography (CT scan), x-rays, and positron emission tomography (PET) scan are often used to discern whether a diagnosis of skin cancer has reached the metastatic stage. Typical affected organs are the lungs, heart, liver, and brain. CT scans are sometimes used to guide a fine needle or surgical biopsy.
Bone scans are used less often since melanoma is not typically found in the bones. Doctors perform a bone scan by injecting the patient with radioactive material. They then create a profile of the skeleton with a specialized camera.
A self-exam often points the way to a medically-confirmed diagnosis of skin cancer. Self-examination typically includes the ABCD approach where moles are concerned. A refers to the asymmetry of a suspicious mole, one half looking different from the other. B refers to the mole’s border—healthy moles have regular, definite borders. C is for the color of the suspicious mole which may not be a uniform color and may include unusual red, pink, or blue patches. D refers to the diameter of a mole, and healthy moles are usually less than a quarter-inch (6 millimeters) across.