Background Definition

Kaposi's sarcoma (KS), described by Moritz Kaposi in 1872, is a multifocal vascular tumour. It is characterised histologically by a proliferation of spindle-shaped tumour cells surrounding abnormal slit-like vascular channels with extravasated erythrocytes. It may present with cutaneous or mucosal lesions (mouth, gastrointestinal, bronchial), visceral lesions or lymphadenopathy.

There are four clinical variants of KS which appear in specific populations but have identical histological features:

Figure 29.1 Classic Kaposi's sarcoma with oedema of the left leg
Figure 29.2 Endemic (African) Kaposi's sarcoma

1. Classical Kaposi's sarcoma

Classical KS (Figure 29.1) typically affects elderly men of Mediterranean or Jewish descent. It presents with purple-blue ulcerated plaques on the lower legs, which progress over a period of years.

2. Endemic (African) Kaposi's sarcoma

Endemic (or African) KS (Figure 29.2) is common in Sub-saharan Africa. In its nodular form it may run an indolent course similar to classical KS, with oedema of the lower legs. A more aggressive lymphadenopathic form of disseminated endemic KS is seen in children and young adults. Florid and infiltrative types of endemic KS affect adults and are locally aggressive.

3. Transplant/immunosuppression-related Kaposi's sarcoma

Transplant recipients and patients receiving immunosuppressive therapy are another group in which KS occurs. The same ethnic groups in which classical KS is seen are at higher risk but the disease tends to run a more aggressive course.

4. AIDS-related Kaposi's sarcoma

In 1981, Friedman-Kien et al. reported a cluster of young homosexual men with aggressive KS involving lymph nodes and viscera, in association with a syndrome of opportunistic infections and a defect in cell-mediated immunity, subsequently named the acquired immune deficiency syndrome (AIDS).1 This aggressive form of KS (Figures 29.3 and 29.4) was seen up to 20 times more frequently in homosexual men with AIDS than in haemophiliac men with AIDS. KS is now an AIDS-defining illness in the Center for Disease Control guidelines.

Figure 29.3 Kaposi's sarcoma affecting the hard palate in a patient with AIDS

Figure 29.4 Extensive AIDS-related Kaposi's sarcoma

Figure 29.3 Kaposi's sarcoma affecting the hard palate in a patient with AIDS

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