Unicentric Plasma Cell Variant Castleman Disease



Unicentric Plasma Cell Variant Castleman Disease


Pei Lin, MD










Lymph node involved by unicentric Castleman disease, plasma cell variant (CD-PV). Multiple follicles are present and the interfollicular zones are expanded by plasma cells.






Lymph node involved by unicentric CD-PV. This field shows interfollicular plasma cells and a follicle with a small germinal center with involution (regressive changes) image.


TERMINOLOGY


Abbreviations



  • Castleman disease, plasma cell variant (CD-PV)


Synonyms



  • Unicentric Castleman disease, plasma cell variant


  • Angiofollicular lymph node hyperplasia


  • Giant lymph node hyperplasia


  • Angiomatous lymphoid hamartoma


  • Benign giant lymphoma


Definitions



  • Histologically distinctive reaction pattern in lymph node characterized by



    • Marked interfollicular plasmacytosis


    • Regressive (hyaline-vascular) changes in small subset of follicles in subset of cases


ETIOLOGY/PATHOGENESIS


Unknown



  • Data supporting role for dysregulation of interleukin-6 (IL-6) in pathogenesis



    • Lymphocytes in CD-PV express IL-6


    • B cells express IL-6 receptor (CD126)



      • Autocrine or paracrine mechanisms may be involved


    • In mice, forced expression of IL-6 in bone marrow cells causes syndrome that resembles, in part, CD-PV


  • Immune dysregulation also may be involved


  • As defined in this chapter, there is no evidence of human herpes virus 8 (HHV8) infection


CLINICAL ISSUES


Epidemiology



  • Incidence



    • Accounts for 10-20% of localized or unicentric cases of CD


  • Age



    • Broad range; median in 3rd-4th decade


  • Gender



    • No preference


Site



  • Peripheral lymph nodes most common


  • Mediastinal involvement less common (than hyaline vascular variant of CD)


Presentation



  • Most patients present with lymphadenopathy without systemic symptoms


  • 10-20% of patients reported in literature had systemic symptoms



    • Fever, night sweats, weight loss, malaise


    • However, it seems likely that many of these patients were HHV8(+)



      • Therefore better classified as HHV8-associated &/or multicentric CD


  • Small subset of patients reported were associated with POEMS syndrome



    • POEMS = peripheral neuropathy, organomegaly, endocrinopathy, monoclonal M protein, skin lesions


    • These patients also likely to be HHV8(+)



      • Probably better classified as HHV8-associated &/or multicentric CD


Laboratory Tests



  • Many patients lack laboratory abnormalities


  • Subset of patients (˜ 10-20%) can have cytopenias



    • Anemia and thrombocytopenia


  • Serum IL-6 levels can be increased


Treatment



  • Surgical approaches



    • Usually curative by excision



Prognosis



  • Good


  • Small subset of patients may evolve to multicentric CD



    • Possibly were cases of multicentric CD at time of initial biopsy


IMAGE FINDINGS


Radiographic Findings



  • Lymphadenopathy



    • Often multiple lymph nodes in an anatomic group are large


  • PET scan shows increased FDG uptake


MACROSCOPIC FEATURES


Size



  • Usually lymphadenopathy is of modest size


MICROSCOPIC PATHOLOGY


Histologic Features



  • Less well defined than HV-CD


  • Preserved overall lymph node architecture


  • Marked plasmacytosis in interfollicular areas



    • Some plasma cells can be binucleated


  • Vascularity in interfollicular areas can be prominent


  • Sinuses usually patent


  • Widely spaced lymphoid follicles


  • Lymphoid follicles contain hyperplastic germinal centers, but small subset of germinal centers often show regressive changes



    • Resemble follicles seen in CD-HV


    • Others have used term “mixed or transitional” type because of these follicles


    • Atretic follicles are usually present and part of spectrum of CD-PV


  • Mantle zones are usually well defined and can be expanded



    • Plasmablasts are absent or rare in mantle zones


Cytologic Features



  • Plasma cells are cytologically normal without atypia


  • Lymphocytes show range in cytologic appearance


  • Difficult to establish specific diagnosis of CD-PV by fine needle aspiration


ANCILLARY TESTS


Immunohistochemistry



  • Interfollicular plasma cells express polytypic immunoglobulin light chains


  • Follicles composed of polytypic B cells and T cells



    • Germinal centers are Bcl-2(-)


    • Atretic follicles show increased follicular dendritic cells



      • CD21(+), CD23(+), CD35(+)


  • Rare cases are reported with monoclonal plasma cells



    • These cases most likely HHV8(+) &/or multicentric CD

Jul 8, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Unicentric Plasma Cell Variant Castleman Disease
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