Kaposi Sarcoma With Intravascular Primary Effusion Lymphoma in the Skin: A Potential Pitfall in HHV8 Immunohistochemistry Interpretation.

Primary effusion lymphoma is a rare, clinically aggressive large B-cell neoplasm universally associated with human herpesvirus 8 that occurs in the setting of immune compromise. It is classically described as a lymphomatous effusion occurring within body cavities. Recently, however, solid tumor masses, and rarely an intravascular form, have been described. We report a case of a cutaneous intravascular primary effusion lymphoma occurring within ectatic vascular spaces of a Kaposi sarcoma skin lesion in a human immunodeficiency virus-positive adult. Human herpesvirus 8 immunohistochemistry was positive in the nuclei of the Kaposi sarcoma spindled cells as well as within large intravascular plasmacytoid cells. This unusual case highlights the importance of careful assessment of the nature of human herpesvirus 8-positive staining cells in an otherwise typical Kaposi sarcoma. A careful search for dual pathology in immune-compromised patients as well as the importance of histologic assessment of skin lesions in human immunodeficiency virus-positive patients is also highlighted.