Approach

The correct diagnosis of the presenting lesions of KS will be facilitated by recognition of the clinical category of the patient (classic [sporadic]; endemic [observed in sub-Saharan Africa]; HIV-associated [formerly known as epidemic or AIDS-related]; iatrogenic [transplant-related]) and the appearance of the lesions. The diagnosis is confirmed by biopsy and histopathology.[2][4][5]​​[Figure caption and citation for the preceding image starts]: Photomicrograph of the histopathology of Kaposi sarcoma showing fascicles of vasoformative spindle-shaped tumor cells (hematoxylin and eosin stain)From the collection of Dr Liron Pantanowitz; used with permission [Citation ends].com.bmj.content.model.Caption@3599aade

History

Patients may report occurrences of skin lesions often accompanied by psychosocial stress (anxiety). Cutaneous lesions are usually painless and nonpruritic and so may also be asymptomatic.[4] Tumors on the lower leg may affect gait. Lymphedema of the legs, genitalia, and face may be disfiguring and sometimes painful. Oral lesions can bleed and ulcerate, and may affect mastication, speech, and swallowing.

KS of the gastrointestinal (GI) tract can cause weight loss, abdominal pain, nausea and vomiting, ileus, upper or lower GI tract bleeding, malabsorption, intestinal obstruction, and, infrequently, diarrhea.[4] Pulmonary KS can present with dyspnea, fever, cough, hemoptysis, or chest pain.[4] KS may also be an incidental finding in people presenting with, or being followed for, an underlying condition such as HIV infection or organ transplantation.

Existing human herpesvirus-8 (HHV-8) infection is necessary for the development of KS. Individuals with other HHV-8-related diseases, such as multicentric Castleman disease and primary effusion lymphoma (PEL), are also at risk for developing concomitant KS.[26][Figure caption and citation for the preceding image starts]: Multiple pink-purple Kaposi sarcoma nodules on the lower extremityFrom the collection of Dr Bruce J. Dezube; used with permission [Citation ends].com.bmj.content.model.Caption@1406ef84

Examination

Initial evaluation of a patient with KS includes a complete physical examination with special attention to areas frequently affected by lesions, such as the lower extremities, face, oral mucosa, and genitalia.[4][5] Lymph nodes should be examined.[2][5] Mucocutaneous lesions and lymphedema may be extensive and should be documented.

Skin lesions of KS typically have the following characteristics:[3]

  • Multifocal

  • Asymmetrically distributed

  • Varied size

  • Varied color (pink, red, purple, brown, or blue)

  • Nodular

  • Papular

  • Plaque-like

  • Bullous-like

  • Indurated (woody)

  • Verrucous

  • Fungating

  • Ulcerated

  • Infected.

[Figure caption and citation for the preceding image starts]: Multiple pink-purple Kaposi sarcoma nodules on the lower extremityFrom the collection of Dr Bruce J. Dezube; used with permission [Citation ends].com.bmj.content.model.Caption@990addb[Figure caption and citation for the preceding image starts]: Kaposi sarcoma cutaneous purple-brown plaque on the footFrom the collection of Dr Bruce J. Dezube; used with permission [Citation ends].com.bmj.content.model.Caption@520f93d9

Visceral involvement, with and without mucocutaneous lesions, should be determined with attention specifically directed to the lymph nodes, GI tract, and respiratory system.

Investigations

If HIV status is unknown, an HIV test should be performed in individuals presenting with KS.[2][3][5]​​ If the patient is HIV-positive, a CD4+ T-cell count and HIV viral load should be obtained.

Clinically suspected skin lesions should be confirmed by a small punch biopsy of 2-4 mm with histopathology. Skin punch biopsies are easy to perform and readily help exclude mimics. Histopathology shows characteristic atypical spindle-shaped cells.[36] Immunohistochemistry techniques can be used to detect the following markers expressed by Kaposi sarcoma lesional cells: latency-associated nuclear antigen-1 (LANA-1, a surrogate marker for HHV-8); CD31/CD34 (vascular endothelial cell immunomarkers), and D2-40 (a lymphatic cell immunomarker).[37][38] ​A positive LANA-1 stain can establish KS diagnosis; CD31 and CD34 may be useful if it is unclear whether the tumor is vascular in origin.[2][5][38]​​ Determination of HHV-8 (polymerase chain reaction [PCR]) and assays for HHV-8 antibodies are not typically warranted in routine clinical practice, but may be available on an individual basis.[3][5]​ 

Bone marrow function, and hepatic and renal function, will need to be evaluated in patients requiring systemic chemotherapy. Obtaining a CBC and comprehensive metabolic panel forms part of the initial work up.[2]

Imaging studies and subsequent investigations

Lung imaging with chest x-ray is useful to screen for pulmonary KS in patients with advanced disease or respiratory symptoms.[2][5]​​ Concomitant pulmonary infection must be excluded. Chest computed tomography (CT) and bronchoscopy can be used to establish a diagnosis of pulmonary KS in patients with an abnormal chest x-ray.[2][5]​​ Biopsy of respiratory tract lesions is relatively contraindicated because of the risk of bleeding.[39][40][41]

Lymphadenopathy should be examined histologically if a coexisting disorder (e.g., infection, lymphoma, multicentric Castleman disease) is suspected.[2][42]​ Fecal occult blood is useful to screen for GI tract disease if visceral involvement is suspected.[2] GI endoscopy and CT of the abdomen/pelvis in symptomatic individuals are not recommended as part of routine evaluation in the absence of iron deficiency, GI blood loss, or GI symptoms.[2][4]​​​​ CT scan, positron emission tomography (PET) scan, and magnetic resonance imaging (MRI) may be helpful for evaluating deep nodal and visceral KS, and bone lesions. Bone lesions are best detected by CT scan and MRI, as they frequently go undetected on plain x-ray or bone scans.[43]

If chemotherapy or radiation therapy is planned, pregnancy testing should be performed in patients of childbearing potential.[5]

[Figure caption and citation for the preceding image starts]: Photomicrograph of the histopathology of Kaposi sarcoma showing fascicles of vasoformative spindle-shaped tumor cells (hematoxylin and eosin stain)From the collection of Dr Liron Pantanowitz; used with permission [Citation ends].com.bmj.content.model.Caption@68a97ae0[Figure caption and citation for the preceding image starts]: CT scan of the chest showing a reticular pattern due to pulmonary involvement by Kaposi sarcomaFrom the collection of Dr Bruce J. Dezube; used with permission [Citation ends].com.bmj.content.model.Caption@930f4b

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