An Epstein-Barr virus-positive classical Hodgkin lymphoma with exclusive sinusoidal growth pattern: An unusual morphologic variant.

Classical Hodgkin lymphoma (cHL) typically involves lymph node parenchyma, and a case with Hodgkin cells confined within nodal sinusoids is extremely rare. Herein we report a case of cHL with a sinusoidal growth pattern. This 15-year old patient presented with B symptoms and was found to have bilateral cervical lymphadenopathy and an anterior mediastinal mass. Biopsy of a cervical lymph node demonstrated cohesive clusters of Reed-Sternberg (RS)-like cells suggestive of sinusoidal growth with an extrasinusoidal mixed inflammatory cell infiltrate characteristic of the microenvironment seen in cHL. The RS cells/variants were positive for CD30 and CD15, and showed down-regulation of B-cell program and CD45, an immunophenotypic profile consistent with cHL. The sinusoidal growth pattern was also highlighted by EBV staining. To the best of our knowledge, this is the first case of EBV-positive cHL that displays a sinusoidal growth pattern. The patient was treated with children's high risk cHL chemotherapy protocol and responded well.