Merkel cell carcinoma in collision with squamous cell carcinoma and basal cell carcinoma in a patient on ruxolitinib treatment for myeloproliferative neoplasm

March 20, 2024


JAAD Case Reports

Publication Date

March 20, 2024


Barrera-Penagos V, Castellanos-Leguizamón D, Hakim-Tawil J, Santivañez J, Rodríguez-Urrego P, López-Takegami J Summary

Janus kinase inhibitors (JAK-I) are drugs that help the immune system fight diseases like rare blood cancers. However, as other studies have found, JAK-I has an immunosuppressive effect (the immune response is weakened) which may increase the risk of developing other cancers. This paper specifically discusses the case of an 80-year-old patient with a rare blood cancer who was treated with JAK-I and then developed two large tumors, which were a mix of skin cancers including MCC. Because JAK-I weakens parts of our immune system that activate our “killer T-cells” to fight MCC, patients on JAK-I (or other drugs that weaken our immune system) may have a higher risk of developing MCC, or a harder time fighting off the cancer. Patients diagnosed with MCC who are on JAK-I or other immunosuppressive drugs should have a careful discussion with their doctors to consider stopping the immunosuppressive drugs while getting treated for MCC.


Janus kinase inhibitors (JAK-I) have been gaining importance in the treatment of myeloproliferative neoplasms (MPNs), such as myelofibrosis and polycythemia vera. One of the most used JAK-I indicated for the treatment MPN is ruxolitinib, a potent oral selective inhibitor of JAK1 and JAK2. Its use has been shown to improve the quality of life of patients with MPN, reducing splenomegaly and symptom burden compared with the previous standard treatment., However, clinical trials that have evaluated the long-term effects of the use of ruxolitinib have found cases of newly diagnosed nonmelanoma skin cancer (NMSC) after 5 years of exposure among patients with myelofibrosis and polycythemia vera. Herein we present the case of a patient with a V617F JAK2-positive MPN treated with ruxolitinib, who developed multiple skin tumors after 6 years of treatment. Among these, 2 synchronous, fast-growing lesions emerged, composed of Merkel cell carcinoma (MCC) in collision with squamous cell carcinoma (SCC) and basal cell carcinoma (BCC). This case highlights the importance of active dermatological monitoring, especially in patients with sun skin-damage history and in treatment with JAK-I for myeloproliferative conditions.

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