Citation, DOI & article data
Kaposi sarcoma (KS) is a low-to-intermediate grade mesenchymal tumor that involves the lymphovascular system. The tumor can involve the pulmonary, gastrointestinal, cutaneous and musculoskeletal systems. Although it is often thought of as an AIDS-related condition, it may also be seen in other patient groups.
- lymphoproliferative disorders (particularly with the classic form)
There are four recognized variants 1:
- classic (chronic): multiple distal lower extremity predominant purple skin plaques and rarely involve visceral organs
- endemic (lymphadenopathic): common in equatorial Africa
- iatrogenic (organ transplant-related)
- AIDS-related (epidemic): usually requires the CD4 count to drop <200 cells/mm3; may develop in up to 35% of patients with AIDS 2 and when developed it is considered an AIDS-defining illness
The latter two variants are much more common.
An etiological association with human herpes virus type 8 (HHV8) has been postulated. The AIDS-related and post-transplant variants are also associated with immunosuppressive states.
Histologically can comprise of sheets of plump spindle-shaped cells surrounding and lining slit-like vascular spaces.
There is a wide spectrum of imaging findings depending on which organ is involved. However, most features are non-specific 1,2,4 but may assist in diagnosis if relevant clinical risk factors (e.g. background AIDS history) are evident. In 30% of cases, there is no concurrent cutaneous involvement 1.
The following features may be seen on chest radiographs:
- parenchymal nodular or reticular opacities with a predilection towards perihilar mid to lower zones; has two major patterns
- linear interstitial nodules
- fluffy ill-defined nodules
- pleural effusion(s)
- mediastinal and/or hilar lymphadenopathy
On HRCT of the chest:
- ill-defined (flame-shaped) nodular opacities with usually bilateral and roughly symmetrical perilymphatic and peribronchovascular distribution (1-2 mm) 1
- may have surrounding patchy ground glass changes
- interlobular septal thickening
- lymphadenopathy (may be present in up to 50%) 5
- lymphadenopathy is typically of high attenuation 6
On liver CT:
- ill-defined multifocal peripheral portal nodules with variable attenuation (commonest hepatic neoplasm in AIDS patients) 1,4
Scintigraphy may be useful if concurrent opportunistic infection or lymphoma is suspected:
- thallium-201: usually positive in both lymphoma and Kaposi sarcoma
- gallium-67: usually negative in Kaposi sarcoma but positive in lymphoma and infection
History and etymology
This condition was first described by Moritz Kaposi (1837-1902), an Austro-Hungarian dermatologist, in 1872.
For thoracic involvement consider:
- 1. Restrepo C, Martínez S, Lemos J et al. Imaging Manifestations of Kaposi Sarcoma. Radiographics. 2006;26(4):1169-85. doi:10.1148/rg.264055129 - Pubmed
- 2. Davis S, Henschke C, Chamides B, Westcott J. Intrathoracic Kaposi Sarcoma in AIDS Patients: Radiographic-Pathologic Correlation. Radiology. 1987;163(2):495-500. doi:10.1148/radiology.163.2.3562832 - Pubmed
- 3. Witte M, Fiala M, McNeill G, Witte C, Williams W, Szabo J. Lymphangioscintigraphy in AIDS-Associated Kaposi Sarcoma. AJR Am J Roentgenol. 1990;155(2):311-5. doi:10.2214/ajr.155.2.2115258 - Pubmed
- 4. Luburich P, Bru C, Ayuso M, Azón A, Condom E. Hepatic Kaposi Sarcoma in AIDS: US and CT Findings. Radiology. 1990;175(1):172-4. doi:10.1148/radiology.175.1.2179988 - Pubmed
- 5. Hartman T, Primack S, Müller N, Staples C. Diagnosis of Thoracic Complications in AIDS: Accuracy of CT. AJR Am J Roentgenol. 1994;162(3):547-53. doi:10.2214/ajr.162.3.8109494 - Pubmed
- 6. Herts B, Megibow A, Birnbaum B, Kanzer G, Noz M. High-Attenuation Lymphadenopathy in AIDS Patients: Significance of Findings at CT. Radiology. 1992;185(3):777-81. doi:10.1148/radiology.185.3.1438762 - Pubmed
- 7. Kanne J, Rohrmann C, Lichtenstein J. Eponyms in Radiology of the Digestive Tract: Historical Perspectives and Imaging Appearances. Part 2. Liver, Biliary System, Pancreas, Peritoneum, and Systemic Disease. Radiographics. 2006;26(2):465-80. doi:10.1148/rg.262055130 - Pubmed
- 8. Ganem D. KSHV and the Pathogenesis of Kaposi Sarcoma: Listening to Human Biology and Medicine. J Clin Invest. 2010;120(4):939-49. doi:10.1172/JCI40567 - Pubmed