Kaposi sarcoma

Kaposi sarcoma (KS) is a low-to-intermediate grade mesenchymal tumour that involves the lymphovascular system. The tumour can involve the pulmonary, gastrointestinal, cutaneous and musculoskeletal systems.

There are four recognised 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.

Aetiology

An aetiological association with human herpes virus type 8 (HHV8) has been postulated. The AIDS-related and post-transplant variant are associated with immunosuppressive states.

Histology

Histologically can comprise of sheets of plump spindle-shaped cells surrounding and lining slit-like vascular spaces.

Associations
  • lymphoproliferative disorders (particularly with the classic form)

There is a wide spectrum of imaging findings depending on which organ is involved. However, most features are nonspecific 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.

Plain radiograph

The following features may be seen on chest radiographs:

  • parenchymal nodular or reticular opacities with predilection towards peri-hilar mid to lower zones; has two major patterns
    • linear interstitial nodules
    • fluffy ill-defined nodules
  • pleural effusion(s)
  • mediastinal and/or hilar lymphadenopathy
CT

On HRCT of the chest:

On liver CT:

  • ill-defined multifocal peripheral portal nodules with variable attenuation (commonest hepatic neoplasm in AIDS patients) 1,4
Nuclear medicine

Scintigraphy may be useful if concurrent opportunistic infection or lymphoma is suspected:

  • Th201: usually positive in both lymphoma and Kaposi sarcoma
  • Ga67: usually negative in Kaposi sarcoma but positive in lymphoma and infection

This condition was first described by Moritz Kaposi (1837-1902), Austro-Hungarian dermatologist in 1872.

For thoracic involvement consider

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Article Information

rID: 7539
System: Chest
Section: Pathology
Synonyms or Alternate Spellings:
  • Kaposi Sarcoma
  • Kaposi sarcoma (KS)
  • Kaposi Sarcomas

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    Figure 1: non-AIDS associated KS skin lesions
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    Case 1: Kaposi's sarcoma of the lung
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