Metastatic Merkel Cell Carcinoma Masquerading as Multiple Immune-Related Adverse Events

Abstract EN

Merkel cell carcinoma is a rare cutaneous neuroendocrine carcinoma with a high rate of regional and distant metastasis and mortality.

Here, we report a novel case of Merkel cell carcinoma which presented as a primary lesion to the left cheek with regional lymph node involvement and was treated with pembrolizumab and radiation.

Widely metastatic disease eventually revealed on autopsy clinically mimicked immune-related organ insult leading to management with immunosuppressants.

The patient also had a biopsy-confirmed immune-related cutaneous adverse event during admission.

The case highlights a rare circumstance in which disease progression masqueraded as multiple immune-related end-organ adverse events.

Contribution of on-target anti-PD-1 toxicity remains a possibility.