Diagnosis

Tests and procedures used to diagnose Merkel cell carcinoma include:

• Physical exam. Your doctor will examine your skin for unusual moles, freckles, pigmented spots and other growths.
• Removing a sample of suspicious skin. During a procedure called a skin biopsy, your doctor removes the tumor or a sample of the tumor from your skin. The sample is analyzed in a laboratory to look for signs of cancer.

Determining the extent

Your doctor may use the following tests to help determine whether the cancer has spread beyond your skin:

• Sentinel node biopsy. A sentinel node biopsy is a procedure to determine whether cancer has spread to your lymph nodes. This procedure involves injecting a dye near the cancer. The dye then flows through the lymphatic system to your lymph nodes.

  The first lymph nodes that receive the dye are called the sentinel nodes. Your doctor removes these lymph nodes and looks for cancerous cells under a microscope.

• Imaging tests. Your doctor may recommend a chest X-ray and a CT scan of your chest and abdomen to help determine whether the cancer has spread to other organs.

  Your doctor may also consider other imaging tests such as a positron emission tomography (PET) scan or an octreotide scan — a test that uses an injection of a radioactive tracer to check for the spread of cancer cells.