Melanoma is a type of fast-growing skin cancer that can spread to lymph nodes and other parts of the body. While melanoma accounts for only 1% of all skin cancer cases in the United States, it is responsible for the majority of skin cancer deaths, with approximately 10,000 deaths in the United States each year. Melanomas are often identified as dark, large, irregular lesions which can arise de novo (from otherwise normal appearing skin) or from preexisting evolving moles.
Epidermal inclusion cysts, on the other hand, are keratin (skin protein) filled lesions that appear as bumps or lumps beneath the skin. Patients may opt to surgically remove these cysts when they become uncomfortable/painful, inflamed, associated with drainage, or unsightly. The vast majority of cysts are benign. However, cysts are routinely sent to pathology upon removal due to rare cases where a malignant tumor lies inside or the “cyst” may in fact turn out to be a cancerous tumor which has spread to the skin from inside organs.
Dr. Bajoghli encountered one of these rare instances. A patient came to the office with a bump on the front of his neck near the area of the voice box which appeared to be an epidermal inclusion cyst. He opted to have the lesion excised, and upon removal it appeared to be a normal benign cyst. However, when the sample was examined by pathologists, the cyst was found to contain malignant melanoma, the most dangerous form of skin cancer. The site was re-excised to ensure all of the cancer was removed, and pathologists confirmed that no remaining cancer cells remained.
There have been cases where other types of skin cancers (squamous cell carcinoma and basal cell carcinoma) were found in cysts as well as cases of melanomas arising adjacent to cysts. However, this is the first known case of a melanoma arising directly from an epidermal inclusion cyst. Dr. Bajoghli published his findings in the prestigious dermatology journal Journal of the American Academy of Dermatology.