Kaposi's sarcoma.Kaposi's sarcoma (KS) is a vascular tumor that commonly affects the head and neck, particularly in patients infected with human immunodeficiency virus human immunodeficiency virus n. HIV. Human immunodeficiency virus (HIV) A transmissible retrovirus that causes AIDS in humans. (HIV). Human herpesvirus 8 (HHV8), shed mainly in saliva, is important in KS development. Mucocutaneous mucocutaneous /mu·co·cu·ta·ne·ous/ (-ku-ta´ne-us) pertaining to or affecting the mucous membrane and the skin. mu·co·cu·ta·ne·ous adj. Of or relating to the skin and a mucous membrane. KS and lymph node involvement of the head and neck are often the presenting symptoms of acquired immunodeficiency syndrome acquired immunodeficiency syndrome, see AIDS. (AIDS). In rare cases, KS affects the major salivary glands, either as a primary infiltrating neoplasm within the gland parenchyma Parenchyma A ground tissue of plants chiefly concerned with the manufacture and storage of food. The primary functions of plants, such as photosynthesis, assimilation, respiration, storage, secretion, and excretion—those associated with living or as intranodal involvement. Therefore, it is important to include KS in the differential diagnosis of AIDS-associated salivary gland enlargement. The classic microscopic features of KS are intersecting compact, coalescing, and sheet-like fascicles of uniform, mildly atypical spindle cells that delineate either slit-like or sieve-like vascular spaces that contain extravasated erythrocytes (figure 1). Irregular vascular channels are lined with plump endothelial cells that contain nuclei of irregular size and shape. Mitotic figures, including atypical forms, are easily identified. The tumor nearly always contains characteristic intracellular and extracellular periodic-acid-Schiff-positive, diastase-resistant, glassyhyaline (eosinophilic eosinophilic /eo·sin·o·phil·ic/ (-fil´ik) 1. readily stainable with eosin. 2. pertaining to eosinophils. 3. pertaining to or characterized by eosinophilia. ) globules. Stromal hemosiderin hemosiderin /he·mo·sid·er·in/ (he?mo-sid´er-in) an insoluble form of tissue storage iron, visible microscopically both with and without the use of special stains. he·mo·sid·er·in n. deposition and inflammatory cells, particularly plasma cells, are often present. Immunohistochemical studies show that the spindle cells are positive for endothelial markers, such as factor VIII-related antigen, CD31, and CD34. The detection of HHV8 in KS spindle cells is a useful tool in distinguishing KS from its mimics (figure 2). Histologically, the differential diagnosis includes other vascular neoplasms, such as hemangiomas, angiosarcomas and, less commonly, spindle-cell myoepithelial neoplasms, spindle-cell carcinomas, and melanomas. [FIGURES 1-2 OMITTED] KS in HIV-infected patients can be treated with highly active antiretroviral therapy Noun 1. highly active antiretroviral therapy - a combination of protease inhibitors taken with reverse transcriptase inhibitors; used in treating AIDS and HIV drug cocktail, HAART , salivary gland chemotherapy, and radiation and/or complete surgical excision. Suggested reading Castle JT, Thompson LDR. Kaposi sarcoma of major salivary gland origin. A clinicopathologic series of six cases. Cancer 2000;88:15-23. Pauk J, Huang ML, Brodie SJ, et al. Mucosal shedding of human herpesvirus 8 in men. N Engl J Med 2000;343:1369-77. >From the Department of Pathology, Beth Israel Deaconess Medical Center, Boston. |
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