<unk>  is diagnosed based on patient history, physical exam, laboratory testing, radiologic imaging, and microscopic analysis (histology) of biopsied tissue from an enlarged lymph node. Formal criteria for the diagnosis of<unk>  have not been published; however, diagnosis requires enlargement of lymph nodes in multiple lymph node regions (typically confirmed with radiologic imaging), histologic changes consistent with<unk>  on biopsy of an enlarged lymph node, and confirmation of<unk> -8 infection by LANA-1 lymph node staining or peripheral blood polymerase chain reaction for<unk> -8. HIV testing is useful for management, but a positive result is not necessary for to diagnose<unk> . Classification Castleman disease describes a group of at least three distinct disorders—unicentric Castleman disease (UCD), human herpesvirus<unk>  associated multicentric Castleman disease<unk> , and idiopathic multicentric Castleman disease (iMCD). Identifying the correct subtype of the disease is important, as the three disorders vary significantly in symptoms, clinical findings, disease mechanism, treatment approach, and prognosis. * In Unicentric Castleman disease enlarged lymph nodes with characteristic microscopic findings are present in only a single lymph node region. * In the multicentric subtypes of Castleman disease, enlarged lymph nodes with characteristic findings are present in multiple lymph node regions. The multicentric variants of Castleman disease are further classified by known causes of the disease. *<unk>  is caused by uncontrolled infection with human herpesvirus<unk>  <unk> -8, also known as Kaposi sarcoma-associated herpesvirus). * In idiopathic multicentric Castleman disease (iMCD) the cause of the disease is unknown (idiopathic). Testing for<unk> -8 must be negative to diagnose iMCD. Laboratory testing Laboratory testing may demonstrate low hemoglobin levels (anemia), abnormal platelet counts, low albumin levels, elevated inflammatory markers such as C-Reactive Protein, elevated creatinine (kidney dysfunction), increased levels of immunoglobulins, and elevation of molecules involved in inflammation (cytokines), such as interleukin 6 (IL-6). Medical imaging Radiologic imaging will demonstrate enlarged lymph nodes in multiple regions, which are typically 18F-fluorodoxyglucose (FDG) avid on positron-emission tomography (PET). Pathology Unlike the other subtypes of Castleman disease, UCD and iMCD, which can present with a spectrum of features on microscopic analysis (histology) of tissue biopsied from an enlarged lymph node, only a plasmablastic pattern of histologic features has been described in<unk> . Plasmablastic features are similar to the plasmacytic features seen in iMCD and UCD, with both demonstrating increased plasma cells in interfollicular spaces. Plasmablastic features are differentiated from plasmacytic features by increased numbers of plasmablasts in follicular mantle zones. Staining with latency-associated nuclear antigen (LANA-1), a marker for<unk> -8 infection, is typically positive.
HHV-8-associated MCD
Cytomegalic inclusion body disease
Epstein–Barr virus–associated lymphoproliferative diseases
AIDS-related lymphoma
Fibrin-associated diffuse large B-cell lymphoma
Tuberculosis in relation to HIV
Hepatitis C and HIV coinfection
Epstein–Barr virus infection