Concurrent Kaposi Sarcoma and B-cell Lymphoma in an HIV-Negative Patient: A Case Report.

We report the case of a 70-year-old non-immunocompromised male patient with coexisting classic Kaposi sarcoma (KS) and stage IV B-cell lymphocytic lymphoma. KS had been evolving insidiously since 2017 but was only confirmed in 2024 following a retrospective histological re-review. The patient received two lines of systemic chemotherapy, rituximab plus bendamustine (R-BENDA) followed by paclitaxel, with transient clinical responses before disease progression. This case suggests that the intrinsic immune dysfunction associated with chronic lymphocytic leukemia (CLL) may provide a permissive environment for human herpesvirus 8 (HHV-8) reactivation in the absence of classically recognized immunodeficiency states (HIV infection, iatrogenic immunosuppression, or primary immunodeficiency) and underscores the importance of histological re-review of atypical or long-standing cutaneous lesions.