Abstract
Herpes simplex virus (HSV) adenitis is a rare but important cause of morbidity in immunocompromised patients. Chronic lymphocytic leukaemia (CLL)/Small lymphocytic lymphoma (SLL) is an indolent disease which impairs the cellular and humoral immunity, predisposing patients to a myriad of infections. Clinically, herpetic adenitis can mimic large cell (Richter's) transformation in patients with CLL. To date, less than 30 cases of HSV adenitis have been reported in the literature. We report a case of a patient with CLL with no prior history of HSV infection, who presented with rapidly enlarging lymph nodes after initial response to idelalisib raising the suspicion of Richter's transformation. However, excisional biopsy of a lymph node revealed HSV adenitis along with CLL, which was confirmed by immunohistochemical staining.