KS (Kaposi sarcoma) is a neoplasm caused by proliferation of the lymphatic endothelium, associated with
HHV-8 infection of endothelial cells. May behave as a benign reactive process or pursue
an aggressive life-threatening course. Secondary skin infections and malignancies
(lymphoma) may complicate KS. Pathogenesis is multifactorial. Chronic lymphoedema
may predispose to KS, and HIV may exacerbate the pathogenicity of HHV-8.
Circulating HHV-8-infected endothelial precursor cells localize to sites, such as the leg, where
unregulated spindle cell proliferation is driven by interactions between activated CD8+
T-cells, HHV-8-induced intracellular signalling pathways, products of oncogenes (viral
and host), and inflammatory cytokines, including HHV-8-encoded IL-6 and, in AIDS
patients, the product of the HIV-1 tat gene.
If immunodeficiency is corrected, e.g. by withdrawing or reducing immunosuppression,
KS may regress. KS lesions also shrink in HIV-positive patients treated with highly
active antiretroviral therapy (HAART). Localized disease may be controlled with
intralesional vinblastine, topical alitretinoin (9-cis-retinoic acid) gel, topical imiquimod,
radiotherapy, laser surgery, or cryosurgery. Systemic options for widespread disease
include IFN-α and multi-agent chemotherapy, e.g. anthracyclines (doxorubicin) or
paclitaxel. The role of angiogenesis inhibitors and other drugs needs further investigation.
What should I look for?
• KS has a predilection for the face, ears, lower limb, including the soles of feet, genitalia,
and oral mucosa.
• Bruise-like purple or brownish red macules and patches which may be subtle in early
disease. Consider the possibility of KS in any immunosuppressed patient with atypical
‘bruises’.
• Blue, purple, red, brown, or brownish red elliptical vascular papules lying in parallel to
the natural lines of cleavage in the skin (Langer lines). These may involve surgical scars.
• Dark blue or purple vascular nodules or indurated hyperkeratotic plaques that may
ulcerate.
• Oral mucosal lesions (vascular patches, papules, or plaques) on the hard palate or, less
often, gums, sometimes with overlying candidiasis. Trauma causes bleeding.
• Lymphadenopathy.
• Lymphoedema affecting the face, genitalia, and/or leg, caused by vascular obstruction,
lymphadenopathy, and local cytokines (commoner in AIDS-related KS). Swelling out of
proportion to cutaneous signs.
What should I do?
• Take a skin biopsy to confirm the diagnosis.
• Exclude immunosuppression, e.g. HIV infection.
• Investigate the GIT and/or respiratory tract, if indicated.