Kaposi's sarcoma

(Moritz Kaposi, 1837 - 1902, Austrian dermatologist), is the most common malignant disease related to AIDS. Until the epidemic of AIDS, Kaposi's sarcoma was regarded primarily as a rare skin tumour of the lower extremities. Now the tumour is frequently encountered in patients with AIDS. It usually affects multiple organs, with widespread lymph node involvement. Involvement of the lungs occurs in 50% of cases, almost always preceded by cutaneous or visceral involvement. Histologically, there is an expansile invasive angiomatosis proliferation of irregular slitlike vessels with atypical endothelial cells. Nodular lesions made of prominent columns of spindle cells may also be present. AIDS-related Kaposi's sarcoma occurs almost exclusively in homosexual or bisexual men or their partners. Human herpes virus-8 has been reported as the causative agent, probably in conjunction with other presumably infectious cofactors. The presenting symptoms of pulmonary Kaposi's sarcoma are commonly cough, dyspnoea, fever and haemoptysis. The radiographic appearances include a peribronchovascular interstitial thickening often spreading peripherally from a perihilar origin as the tumour progresses (Fig.1). With the tumour progression, this thickening becomes nodular. The lower and mid parts of the lungs are affected more frequently than the upper. In more advanced disease, coalescence of nodules, mainly in the lower lobes, leads to areas of consolidation. Kerley lines, sometimes asymmetrical, may also be present, reflecting either tumour infiltration or oedema secondary to central lymphatic obstruction. The associated findings include pleural effusion and hilar and mediastinal lymphadenopathy. CT findings in lung parenchyma include bronchial wall thickening, spiculated nodules and regular or nodular interlobular septal thickening (Fig.2). Soft tissue filling defects impinging into the lumina of the airways, as well as lobar or segmental atelectasis reflecting bulky tumour in the airways, may be depicted. The gross appearance of both mucocutaneous and tracheobronchial Kaposi's sarcoma is characteristic, identified as raised or macular, erythematous or violaceous plaques. The bronchoscopic appearance is sufficiently diagnostic so that biopsy can be avoided. Palliative treatment include chemotherapy associated with local radiation or antiretroviral therapy.

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