This is a report on a 32-year-old man with a history of two previous melanomas with concurrent plaque-type psoriasis. His history dates to 2009, when he was diagnosed with his first melanoma on the right occiput, Clark's level IV, tumor thickness 1.53 mm, nonulcerated, mitotic index 1/mm2. He subsequently developed nodal recurrence after an initial negative sentinel lymph node biopsy and was treated with complete lymph node dissection. In 2012, he was diagnosed with a second primary melanoma on the right upper chest, Clark's level IV, tumor thickness 0.9 mm, nonulcerated, mitotic index 3/mm2. Due to worsening longstanding plaque-type psoriasis in 2015 he was placed on apremilast, with a dramatic improvement in his psoriasis within 4 months of starting therapy. Shortly thereafter the patient developed multiple blue-colored skin papules on the scalp near his first melanoma and on the trunk and upper limbs that on biopsy proved to be due to cutaneous metastasis of melanoma. The patient discontinued the apremilast as there was a concern that his tumor had recurred because of the drug. Apremilast is a phosphodiesterase-4 inhibitor that impairs the innate immune system, which mediates cancer immunosurveillance. It is postulated that the use of apremilast in our patient resulted in impaired cancer immunosurveillance and led to a recurrence of his melanoma. Although one cannot exclude the possibility of coincidental recurrence of an already metastatic melanoma (to the lymph nodes), caution should be exercised when considering apremilast in the context of patients with known malignancy, in particular melanoma.
Keywords: Apremilast; Cancer immunosurveillance; Melanoma; Psoriasis.