ABSTRACT
Diffuse large B‑cell lymphoma (DLBCL) is the most common subtype of non‑Hodgkin lymphoma with diverse clinical, pathological and genetic features. An 80‑year‑old woman was diagnosed with a stage IV‑X‑A (Ann Arbor staging system) low grade systemic follicular lymphoma (FL). Four months after the diagnosis, she developed asymptomatic, indurated, annular erythematous plaques with centrifugal growth on the abdomen, arms and neck. The skin biopsy revealed a dermal infiltration compatible with diffuse large B‑cell lymphoma. Light chain restriction by flow cytometry was demonstrated. The variable, diverse and joining genes of immunoglobulin G heavy chains were sequenced and cloned, and showed the same pattern for both the initial follicular lymphoma and the skin infiltration. Translocation t (14;18) was present in both samples. Based on these findings, a diagnosis of transformation of follicular lymphoma into diffuse large B cell lymphoma was made. Although other hematological disorders such as primary cutaneous diffuse large B cell lymphoma, mycosis fungoides and the cutaneous infiltration of chronic juvenile myeloid leukemia can present as annular lesions, we were unable to find any previous reports of these as a manifestation of cutaneous infiltration by systemic non‑Hodgkin lymphoma.