BACKGROUNDThe sudden development of facial plaques and nodules may be an alarming clinical sign for underlying malignancies. Nevertheless, a broad range of inflammatory and infectious diseases must be considered as well in the differential diagnosis.CASE REPORTWe report on a 53-year-old male patient with a left-sided cheek infiltration with oozing but no lymphadenopathy. He had a medical history of head-and-neck cancer. The primary differential diagnosis was herpes zoster with secondary impetiginization or pyoderma facial. About eight weeks later, the patient presented with progressive formation of nodules and plaques on the face and isotretinoin was stopped. Skin biopsy suggested mycosis fungoid and an oral treatment with bexarotene was started. After limited response for another eight weeks, he returned later with massive facial swelling, nodules and impetiginization. Another skin biopsy was performed to exclude diagnostic error or investigate possible disease progression. Microscopic evaluation and multiplex-polymerase chain reaction confirmed the diagnosis of peripheral T-cell lymphoma, not otherwise specified (PTL-NOS), stage Ia (T1 N0 M0). Imaging techniques excluded metastatic spread. By interdisciplinary tumour board, R-CHOP (rituximab, cyclophosphamide, hydroxyl-doxorubicin, vincristine, and prednisolone) was recommended and initiated by hemato-oncologists.CONCLUSIONSPLT-NOS confirmed in the present patient has a poor prognosis with a 5-year survival rate of less than 20%.