Mehr Gupta¹, Soumya Nair¹

¹NSW Health Pathology, John Hunter Hospital, Newcastle, Australia 

HSV lymphadenitis is rare, with <30 cases reported. The majority had underlying haematological malignancies, most commonly treated CLL/SLL, though treatment-naïve cases have also been reported. Clinically, HSV lymphadenitis can mimic the more common phenomenon of Richter transformation.

A 71-year-old male presented with progressive tender lymphadenopathy, B symptoms and a raised WBC count. PET scan showed FDG avid lymph nodes. He had chemotherapy 15 years ago for symptomatic CLL/SLL.

 

The core biopsy from a groin lymph node showed monomorphic small lymphoid cells consistent with CLL with massive necrosis. Occasional enlarged/mummified cells with chromatin margination were present within the necrosis. Sheets of large cells were absent. On immunohistochemistry, the neoplastic lymphoid cells co-expressed CD20 and CD5, with scattered positivity for CD23, LEF1 and low Ki67, confirming CLL/SLL. The large mummified cells within necrosis were positive for HSV viral immunostain. 

The patient received treatment with high-dose antivirals and IVIG. One year later, he remains well on prophylactic Valaciclovir.   

HSV lymphadenitis is a rare but important mimic of Richter transformation in patients with CLL/SLL, with significant therapeutic implications. Pathologists should have high suspicion in cases clinically presenting as Richter transformation but histologically showing necrotising lymphadenitis, with or without viral cytopathic effect.