Publication date: Jun 25, 2025

Background: Reports of primary cutaneous lymphomas (CLs) following COVID-19 vaccines are extremely rare. Nevertheless, clinicians should be aware of a potential association between these events. Here, we report a case of the development and rapid progression of mycosis fungoides (MF) with lymph node involvement after COVID-19 vaccination. Case presentation: A 75-year-old female developed disseminated plaques and patches shortly after receiving the first dose of the SARS-CoV-2 mRNA vaccine. Within one month following the second dose of the mRNA vaccine, she additionally experienced rapid progression, leading to the development of tumors and inguinal lymphadenopathy. Blood and visceral involvement were excluded. The clinicopathological findings were consistent with the diagnosis of MF, and systemic methotrexate with topical treatment was implemented, resulting in remission of the lesions. Conclusions: The presented case of the development and rapid progression of MF after the SARS-CoV-2 mRNA vaccine raises the question of the possible immunomodulatory or oncomodulatory effects of mRNA vaccines. It prompted us to conduct a review outlining the mechanisms potentially causing the mRNA vaccine-associated CLs. We have performed an extensive literature search to determine an explanation for the observed phenomenon. Accumulated evidence suggests a link between CL occurrence and immunization with an mRNA vaccine. The proposed hypothesis revolves around shared signaling pathways that are enhanced by SARS-CoV-2 mRNA vaccines, thus driving the pathogenesis of MF. We want to raise clinicians’ attention to the rare side effects of COVID-19 vaccines and emphasize the need for thorough monitoring of patients with altered immunity in the course of various lymphoproliferative disorders.

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