A case report of eyelid Merkel cell carcinoma occurring under treatment with nivolumab for a lung adenocarcinoma.

BACKGROUND

Merkel cell carcinoma (MCC) is a rare neuroendocrine malignancy of the skin characterized by high aggressiveness. Four main factors are implicated in its development: immunosuppression, ultraviolet radiation, age and the Merkel cell polyomavirus (MCPyV). In recent years, immune checkpoint inhibitors have shown clinical activity in MCC treatment.

CASE PRESENTATION

We report the case of an 82-year-old man with a lung adenocarcinoma diagnosis, who underwent immunotherapy with nivolumab as second-line treatment. Seven months after the diagnosis of lung cancer during the nivolumab treatment, the patient developed an eyelid MCC, initially misdiagnosed as a chalazion. A palliative radiotherapy was performed with clinical benefit. After a total of seven cycles of nivolumab, computed tomography showed a lung and cerebral disease progression. In addition, clinical conditions worsened leading to the patient's death 13 months after the initial lung cancer diagnosis.

CONCLUSIONS

Cases of co-occurrence of MCC and non-small cell lung cancer (NSCLC) have rarely been reported. Interestingly, common risk factors may be postulated for both cancers. Considering the rarity of this adverse event, its short-term temporal relation with the administration of the drug, which makes a relation improbable, and the coexistence of other risk factors, which may provide plausible explanations, it is possible to conclude according to the WHO Adverse Reaction Terminology that a causal relation between the occurrence of this serious adverse event and the exposure to the drug is unlikely. However, the case deserves to be reported in the literature.