KSHV/HHV-8-associated multicentric Castleman disease and nodal Kaposi sarcoma displaying a lymphangiectatic pattern

A 30-year-old HIV-positive man, noncompliant with highly active antiretroviral therapy, presented with fever, chills, night sweats, and lymphadenopathy. Physical examination was otherwise unremarkable. Positron emission tomography/computed tomography revealed generalized lymphadenopathy (maximum standardized uptake value = 11.6); no extranodal lesions were detected. Laboratory abnormalities included low CD4 count (141 cells/μL) and elevated human herpesvirus 8 (HHV-8) viral load (21 200 copies/mL). An axillary lymph node biopsy showed follicular hyperplasia, fusion/twinning of germinal centers, depletion of germinal center cells, hyalinized penetrating blood vessels, and mantle zone hyperplasia (panel A: hematoxylin and eosin [H&E] stain, 4× lens objective). Scattered plasmablasts (MUM1 positive, CD138 negative, EBER positive, λ positive, immunoglobulin M positive) were seen within the mantle zones (panel A inset: HHV-8/LANA positive, 20× lens objective). A small focus (≈4 mm) of thin-walled, dilated lymphatic spaces with intraluminal proteinaceous material was observed in a single histologic section, lined by bland, flattened endothelial cells (panels B, C, and C inset: H&E stain, 4×, 40×, and 100× lens objectives, respectively), which expressed CD31, CD34, HHV-8/latency-associated nuclear antigen (panel D: 40× lens objective); ERG (panel E: 40× lens objective); and D2-40 (panel F: 40× lens objective). Findings were diagnostic of Kaposi sarcoma herpesvirus (KSHV)/HHV-8–associated multicentric Castleman disease and nodal Kaposi sarcoma (KS), exhibiting a lymphangiectatic pattern.

Although the presence of KS in patients with KSHV/HHV-8–associated multicentric Castleman disease is well recognized, especially in HIV-positive individuals, nodal KS, in the absence of skin/visceral involvement, is uncommon. Among the histopathologic variants of KS, the lymphangiectatic pattern is rare, and is usually encountered at cutaneous or mucosal sites.

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