Atypical Grover Disease Associated With Merkel Cell Carcinoma: A Novel Paraneoplastic Presentation

We report a case of atypical Grover disease occurring in association with Merkel cell carcinoma (MCC). A 63-year-old man presented with a four-month history of generalized pruritic papules. Skin biopsy demonstrated focal intraepidermal acantholysis with dyskeratosis and patchy vacuolar interface change, with negative direct immunofluorescence. Given the widespread eruption, systemic symptoms, and histopathologic findings, an atypical paraneoplastic variant of Grover disease was suspected. Four months later, the patient was diagnosed with metastatic MCC. His dermatologic disease improved with dupilumab and remained controlled during oncologic treatment. To our knowledge, this represents a previously unreported association between atypical Grover disease and MCC and raises the possibility of a paraneoplastic presentation.