Rapidly Fatal Dissemination of Merkel Cell Carcinoma in a Patient Treated with Alemtuzumab for Chronic Lymphocytic Leukemia.

Alemtuzumab is FDA-approved for the treatment of chronic lymphocytic leukemia (CLL). Nonetheless, its use for this indication has fallen out of favor due to serious concerns for infectious complications and increased risks of second malignancies from the profound and lasting immunosuppression. We report here in a patient with a rapidly progressive metastatic Merkel cell carcinoma (MCC) who was previously treated with alemtuzumab and fludarabine for CLL. He developed profound lymphopenia and hypogammaglobulinemia. While the risk of MCC is increased in CLL, its rapid dissemination has not been previously reported with fludarabine alone. In light of the rapidly fatal outcome in our patient due to MCC, we advise caution with the use of alemtuzumab. In patients treated with alemtuzumab for nononcologic indications, aggressive surveillance for cutaneous malignancies should be implemented until its safety profile can be further characterized.