Cutaneous Richter Syndrome mimicking a lower limb cellulitis infection - a case report and review of the literature.

Richter syndrome (RS) is characterized by the development of a high-grade lymphoma in patients with chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL). Herein, we present the case of an 85-year-old woman with a 3-year history of stable asymptomatic CLL that developed a cutaneous RS. The patient presented with painless inflammation in the left leg and foot that was initially diagnosed as a cellulitis infection. She was treated accordingly with ceftriaxone and clindamycin. However, after completing the antibiotic regimen, not only did the inflammation persist, but also superimposed painless nodules gradually appeared on the left leg and foot over the course of four months. The histopathological examination of the nodules revealed a large B-cell cutaneous lymphoma. The patient underwent chemotherapy with CVP, followed by R-CHOP, resulting in a reduction of size of the nodules and remission of the inflammation. The patient died five months after the diagnosis owing to a bacterial pneumonia. We identified in previous reports a total of fifteen cases of cutaneous RS. Most cases presented with rapidly growing tumors or multiple erythematous nodules, similar to our case. This case of a cutaneous RS mimicking a cellulitis infection underlines the importance of a low threshold for performing biopsies of suspicious skin lesions in patients with CLL/SLL.