Background: Poikilodermatous mycosis fungoides (pMF) is a very rare variant of cutaneous T lymphoma. We describe a rare case of erythrodermic poikilodermatous MF associated with mucoepidermoid carcinoma of the right maxillary sinus. Case report: A 66-year-old patient was admitted to the dermatology department for a dry pruritic and poikilodermic erythroderma that had been evolving for two years. He also reported a right unilateral nasal obstruction evolving for one and a half years. Histological examination showed an orthokeratotic epidermis and an edematous superficial and middle dermis, with a thick band of lymphocytic infiltrate in the subepidermis. This infiltrate was made of atypical lymphoid elements of mixed CD3+, CD4+, and CD8+ T phenotype with epidermotropism, allowing for diagnosis of poikilodermic MF to be made. A Deep biopsy of the right maxillary sinus had concluded a high-grade mucoepidermoid carcinoma. Conclusion: Although it is impossible to demonstrate a causal relationship between erythrodermic poikilodermatous MF and our patients mucoepidermoid carcinoma, this observation illustrates that in case of dissociated evolution under treatment of a poikilodermatous erythrodermic MF, the search for a second cancer is desirable. The association between poikilodermatous erythrodermic MF and Hematologic or Solid malignancies, requires long-term follow-up and conditions the prognosis of patients.