Primary cutaneous diffuse large B‐cell lymphoma-leg type (PCDLBCL‐LT) is a rare malignant disease seen in older adults, especially women. In this case report, we discuss a 78-year-old man who developed erythematous indurated plaques on his left shin for about three months. The patient did not report pruritus, weight loss, night sweats, fever, or chills. There was no lymphadenopathy, splenomegaly, or hepatomegaly on the physical examination. A local tissue biopsy was taken from the plaques, confirming the diagnosis of PCDLBCL‐LT via immunohistochemistry. The patient was referred to an oncologist to begin additional evaluation and treatment. According to the literature, chemotherapy with or without adjuvant radiotherapy is the first treatment choice for PCDLBCL‐LT. Monotherapy with rituximab could be considered in some patients with this condition, but the disease may relapse in a short period.