<unk>  is defined by a range of characteristic features seen on microscopic analysis (histology) of tissue from enlarged lymph nodes. Histologic features consistent with<unk>  are categorized into common patterns: * Hyaline vascular: regressed germinal centers, follicular dendritic cell prominence or dysplasia, hypervascularity in interfollicular regions, sclerotic vessels, prominent mantle zones with an “onion-skin” appearance. * Plasmacytic: increased number of follicles with large hyperplastic germinal centers and sheetlike plasmacytosis (increased number plasma cells). * Hypervascular: similar to hyaline vascular features, but seen in iMCD rather than UCD. Includes regressed germinal centers, follicular dendritic cell prominence, hypervascularity in interfollicular regions, and prominent mantle zones with an “onion-skin” appearance. * Mixed: presence of a combination of hyaline vascular, plasmacytic, and/or hypervascular features UCD most commonly demonstrates hyaline vascular features, but plasmacytic features or a mix of features may also be seen. iMCD more commonly demonstrates plasmacytic features, but hypervascular features or a mix of features are also seen. All cases of HHV-8-associated MCD are thought to demonstrate plasmablastic features—similar to plasmacytic features, but with plasmablasts present. The clinical utility of subtyping<unk>  by histologic features is uncertain, as histologic subtypes do not consistently predict<unk>  severity or treatment response. Staining with latency-associated nuclear antigen (LANA-1), a marker for HHV-8 infection, is positive only in HHV-8-associated MCD.<unk> s other than<unk>  can present with similar histologic findings in lymph node tissue, including: * Infectious causes: Epstein-Barr virus, human immunodeficiency virus, tuberculosis * Autoimmune<unk> s: Systemic lupus erythematosus, rheumatoid arthritis * Lymphoproliferative disorders: lymphoma, autoimmune lymphoproliferative syndrome
Castleman disease
Kaposi's sarcoma
Ewing's sarcoma
Histiocytoma
Familial myxovascular fibromas
Bartholin's cyst
Angiomatoid fibrous histiocytoma
Progressive nodular histiocytoma