title: Unique histologic variants of cutaneous Kaposi sarcoma.
abstract: BACKGROUND
  Kaposi sarcoma (KS) is a low-grade angioproliferative neoplasm derived from lymphatic endothelium. Lesions progress from early patch stage into plaques that ultimately form tumor nodules. Several histological variants of KS have been described. The aim of this study is to describe 5 new histopathologic variants of cutaneous KS.
  
  
  METHODS
  Skin biopsy material submitted to a South African dermatopathology practice diagnostic of KS was reviewed. Formalin-fixed, paraffin-embedded tissue was routinely processed and stained with hematoxylin and eosin. Confirmatory immunohistochemical stains included CD31 and latent nuclear antigen-1 (human herpesvirus 8).
  
  
  RESULTS
  All biopsies were procured from HIV-positive patients with a clinical diagnosis of cutaneous KS tumor. Five distinct histologic KS variants, not previously well characterized in the literature, were identified including glomeruloid KS, telangiectatic KS, ecchymotic KS, KS with myoid nodules, and pigmented KS. Tumor cells in all of these variants were immunoreactive for CD31 and latent nuclear antigen-1.
  
  
  CONCLUSIONS
  These unique cases highlight the ability of KS to exhibit variable histomorphology. Their clinical significance requires further study. Dermatopathologists should be aware of these newly described variants to avoid the potential for their misdiagnosis.
authors.affiliation: From the *Department of Pathology, Baystate Medical Center, Tufts University School of Medicine, Springfield, MA; and †Histopathology Department, Ampath Laboratories, Johannesburg and Division of Anatomical Pathology, School of Pathology, University of the Witwatersrand, Johannesburg, South Africa.
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: OʼDonnell
authors.forename: Liron
authors.initials: L
authors.lastname: Pantanowitz
authors.forename: Wayne
authors.initials: W
authors.lastname: Grayson
mesh_terms: D000163:Acquired Immunodeficiency Syndrome / Q000150:complications / Q000473:pathology; D000328:Adult; D014408:Biomarkers, Tumor / Q000378:metabolism; D001706:Biopsy; D005260:Female; D006678:HIV; D019288:Herpesvirus 8, Human / Q000276:immunology / Q000302:isolation & purification; D006801:Humans; D008297:Male; D008875:Middle Aged; D009687:Nuclear Proteins / Q000032:analysis; D010750:Phosphoproteins / Q000032:analysis; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000032:analysis; D012514:Sarcoma, Kaposi / Q000209:etiology / Q000378:metabolism / Q000473:pathology*; D012878:Skin Neoplasms / Q000209:etiology / Q000378:metabolism / Q000473:pathology*; D055815:Young Adult
chemical_list: D014408:Biomarkers, Tumor; D009687:Nuclear Proteins; D010750:Phosphoproteins; D019408:Platelet Endothelial Cell Adhesion Molecule-1; C118485:latent nuclear antigen (LNA)