Metastatic Kaposi Sarcoma



Metastatic Kaposi Sarcoma


Carlos E. Bueso-Ramos, MD, PhD





Key Facts


Etiology/Pathogenesis



  • HHV8 infection plays critical role in most cases



    • Interacts with other factors


Clinical Issues



  • Multiple presentations of KS



    • Sporadic (Mediterranean countries)


    • Endemic (equatorial Africa)


    • Iatrogenic (e.g., post transplantation)


    • Epidemic (HIV-associated)


  • Common sites: Skin, lymph nodes, gastrointestinal tract



    • Often multifocal


Microscopic Pathology



  • Wide histologic spectrum



    • Lacework of thin-walled capillaries


    • Ectatic vessels without pericytes


    • Cleft-like vascular spaces, nonbranching


    • Well-formed bundles and whorls of spindle cells


  • Extravasated erythrocytes


  • Intracytoplasmic eosinophilic hyaline globules


  • Plasma cells and small lymphocytes common


  • Hemosiderin-laden macrophages common


Ancillary Tests



  • Immunohistochemistry



    • HHV8(+), CD31(+), CD34(+)


    • FVIIIRAg(+) in well-differentiated tumors


Top Differential Diagnoses



  • Bacillary angiomatosis


  • Vascular transformation of lymph node sinuses


  • Angiosarcoma







Kaposi sarcoma (KS) associated with multicentric Castleman disease. In the center of the field, focal KS is present among hyaline-vascular follicles. KS is predominantly sinusoidal.






Lymph node involved by Kaposi sarcoma (KS). Note spindle cells and histiocytes with cytoplasmic, eosinophilic hyaline globules image. The globules stain a lighter color than erythrocytes.


TERMINOLOGY


Abbreviations



  • Kaposi sarcoma (KS)


  • Human herpes virus type 8 (HHV8)


Definitions



  • Kaposi sarcoma (KS): Distinctive type of vascular neoplasm that can involve any body site



    • Almost always associated with HHV8 infection


    • Occurs sporadically at low frequency but is much more frequent in setting of immunosuppression


ETIOLOGY/PATHOGENESIS


Infectious Agents



  • HHV-8, a Gammaherpesviridae, is uniformly expressed in KS



    • a.k.a. Kaposi sarcoma-associated herpes virus (KSHV)


  • HHV8 establishes latent infection in most infected KS cells; lytic replication occurs in small subset of KS cells


  • Transmission via sexual and nonsexual routes



    • Saliva contains shed epithelial cells infected by HHV-8


Pathogenesis



  • KS may be multicentric neoplasm at time of conception


  • HHV8 interacts with other factors in pathogenesis



    • e.g., HIV TAT protein has mitogenic and modulating effects on KS cells


  • Angiogenic factors and cytokines are likely to be involved


  • Viral proteins expressed during both latent and lytic phases of viral life cycle contribute to KS pathogenesis


Cell of Origin



  • KS involves progenitor cell from either blood vessel or lymphatic endothelia



    • CD34(+) suggests progenitor endothelial cells


CLINICAL ISSUES


Epidemiology



  • Incidence



    • Varies greatly depending on presentation


  • Age



    • Varies depending on presentation


  • Gender



    • Male predominance in all types of KS


  • Ethnicity



    • Sporadic cases more common around Mediterranean sea


Site



  • Skin, mucosal surfaces, lymph nodes, and all internal organs



    • Skin most common site


    • Oral mucosa and gastrointestinal tract are frequent sites


    • Lymph node involvement usually associated with skin disease



      • Rare patients reported with only lymph node disease


Presentation



  • Presentation of KS can be divided into 4 clinical subsets



    • Sporadic (classic)



      • Involves distal extremities of elderly patients


      • Common in men of Mediterranean and Jewish Ashkenazi origin


      • Clinically indolent


      • Subset of cases can be clinically aggressive; associated with coexistent non-Hodgkin lymphoma


      • In USA, 0.2 per 100,000 tumors


    • African (endemic)




      • Sub-Saharan central Africa


      • 9% of malignant neoplasms in Uganda


      • Children often have generalized lymphadenopathy and aggressive clinical course


      • Subset of aggressive cases likely related to HIV infection


      • Middle-aged adults have KS on extremities; more indolent


    • Iatrogenic immunosuppression



      • KS arises more frequently after organ transplantation or steroid therapy


      • 128x increased incidence after kidney transplantation


      • Usually clinically indolent; can be aggressive


    • AIDS-associated (epidemic)



      • 451x increased incidence in setting of AIDS infection


      • More common in homosexuals; less frequent in IV drug users and hemophiliacs


Natural History



  • In patients who die, KS can be widespread at autopsy



    • Organs: Virtually any organ can be involved



      • Lungs common


Treatment



  • Drugs



    • Highly active antiretroviral therapy (HAART)


Prognosis



  • Depends, in large part, on clinical presentation and associated illness


  • HAART therapy has reduced frequency and improved prognosis for epidemic KS


MACROSCOPIC FEATURES


Lymph Nodes



  • Enlarged and matted

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Jul 8, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Metastatic Kaposi Sarcoma

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