Test yourself: cutaneous mass on the thigh
- 89 Downloads
The skin lesion demonstrated on imaging exams has a hypervascular nature and, in a patient with a history of HIV with irregular treatment, the hypotheses of Kaposi’s sarcoma and bacillary angiomatosis should be considered. The presence of proliferation of spindle-shaped cells and erythrocyte-filled cleft-like vascular structures on histopathology, CD34+ (vascular endothelium marker), and D2-40+ (lymphatic endothelium marker) on immunohistochemistry defines the diagnosis of Kaposi’s sarcoma.
Kaposi’s sarcoma is an angioproliferative neoplasm that can affect multiple systems, such as the skin, mucosa, lymph nodes, gastrointestinal tract, lungs, liver, and spleen . It was first described in 1872 by Moritz Kaposi and, until 1980, was considered a rare condition, but after the onset of the HIV epidemic, its incidence increased and was considered an AIDS-defining disease . The epidemic (or AIDS-associated) form is related to human herpes virus type 8 infection and immunosuppression (mainly by the reduction in CD4 lymphocyte count, especially below 150–200 cells/mm3) and manifests as red, violet, or brown nodular cutaneous lesions that can ulcerate or invade adjacent structures [2, 3, 4].
Imaging evaluation of skin lesions may be useful for detecting local invasion and adenopathy. At ultrasound, Kaposi’s sarcoma cutaneous lesions are usually multilobulated (with well or poorly delimited margins), hypoechoic and, when related to HIV, intensely vascularized by Doppler . At MRI, lesions often have hyperintense signal in fluid-sensitive sequences (T2 WI and STIR) and avid contrast enhancement .
The definitive diagnosis of Kaposi’s sarcoma is confirmed by pathology, usually obtained by patch skin biopsy [1, 7]. Kaposi’s sarcoma is histologically characterized by proliferation of spindle-shaped cells, erythrocyte-filled slit or cleft-like vascular spaces, and chronic inflammatory cell infiltrates [4, 7, 8]. Immunohistochemistry can detect expression of endothelial cell (vascular or lymphatic) and smooth muscle markers . The main differential diagnosis is bacillary angiomatosis, a pseudoneoplastic infection that can also occur in patients with HIV and is caused by the rickettsia-like Rochalimaea quinmna [1, 8, 9]. As in Kaposi’s sarcoma, bacillary angiomatosis also leads to angiomatous skin lesions; however, the latter tends to present more circumscribed and tender lesions with peripheral erythema and much more frequent bone involvement, whereas Kaposi’s sarcoma has less defined and painless lesions without peripheral erythema and less frequent bone involvement [1, 9]. Both can spread and affect lymph nodes, lungs, gastrointestinal tract, liver, and spleen [2, 9]. Histologically, bacillary angiomatosis is characterized by polygonal endothelial cells accompanied by neutrophils, neutrophilic cellular debris, and granular material of bacterial nature [7, 8, 9].
In summary, the differential diagnosis of hypervascularized skin lesions in patients with HIV includes Kaposi’s sarcoma and bacillary angiomatosis. Differentiation between such conditions requires biopsy and detection of proliferation of spindle-shaped cells characterizes Kaposi’s sarcoma.
Angiomatous and hypervascularized cutaneous lesions in HIV patients may be caused by Kaposi’s sarcoma and bacillary angiomatosis and the definitive diagnosis usually requires sampling for histological analysis.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no competing interests.