Panniculitic T-cell lymphoma is a rare, aggressive variant of cutaneous T-cell lymphoma, with fewer than 100 cases described. The main problem is its diagnosis, as both the clinical and the histological features may simulate benign panniculitis. We present the case of a 34-year-old male patient, who had presented with an indurated plaque, sclerodermiform in appearance, on the front of the right thigh for 4 months, later accompanied by fever and constitutional symptoms. The initial diagnosis was cellulitis, but no clinical improvement was seen despite systemic antibiotic therapy. After two skin biopsies, the patient was diagnosed with panniculitic cutaneous T-cell lymphoma. The patient was treated with 8 cycles of CHOP chemotherapy, with resolution of the symptoms.