Non-Melanoma Skin Cancers Coverage from Every Angle

Case Study: Malignant Melanoma After Merkel Cell Carcinoma

By: Anna Nowogrodzki
Posted: Friday, October 16, 2020

According to a recent case report, an elderly patient developed malignant melanoma on his big toe 2 years after total resection of a Merkel cell carcinoma on his cheek. Toshiyuki Yamamoto, MD, of Fukushima Medical University in Japan, and colleagues published their findings in Anais Brasileiros de Dermatologia.

“Systemic immunosuppression associated with aging and/or UV irradiation may be a common cause of both conditions in the present case,” the authors wrote.

A 98-year-old man underwent total resection of a Merkel cell carcinoma (35 mm in diameter on his left cheek). He chose not to receive further treatment because of his age. Two years later, he was diagnosed with a malignant melanoma on his right hallux. The authors’ histologic analysis of the melanoma showed many atypical cells that were immunoreactive for MART-1 and HMB-45, which had infiltrated from the epidermis to the dermis.

According to the authors, an article in the medical literature reported that Merkel cell carcinoma and malignant melanoma were linked to sun exposure and immunosuppression. The authors of the older article speculated that sun exposure might increase systemic immunosuppression via the induction of regulatory T cells by ultraviolet rays. Dr. Yamamoto and colleagues also cited a more recent review article suggesting patients may be at increased risk of second primary cancer after a Merkel cell carcinoma diagnosis. Another recent article on the topic presented a case of a patient who developed Merkel cell carcinoma while being treated for malignant melanoma with immune checkpoint inhibitors.

“Given the increase of immune checkpoint inhibitors used to treat malignant melanoma, the number of cases in which both Merkel cell carcinoma and malignant melanoma develop in a patient may increase in Japan, as well as around the world,” proposed the authors.

Disclosure: The study authors reported no conflicts of interest.

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