Teaching Case

52-years-old male patient with AIDS urgently referred to the Radiology Department for contrast-enhanced CT requested “to rule out cerebral opportunistic diseases” prior to starting highly active antiretroviral therapy.

Unenhanced and contrast-enhanced axial CT images showed no intracranial signs of recent haemorrhage, abnormal space-occupying nor enhancing lesions consistent with active opportunistic diseases.
A marked, diffuse (although uneven) soft-tissue thickening with positive contrast enhancement was seen involving the skin, subcutaneous fat of the scalp bilaterally, with adhesion to the superficial fascia of the temporal muscle and the thecal periosteum. Bone erosions or osteolysis were excluded with assessment of images reconstructed with bone algorithms.
Clinically, diffuse involvement of the scalp and portions of the face by purple, erythematous cutaneous lesions, were associated with involvement of the oral cavity and the oesophageal mucosa. Diagnosis of extensive Kaposi's sarcoma was confirmed by means of superficial lesions biopsy. Extended body imaging (not shown) did not detect synchronous lesions, particularly in the lungs and abdomen.
Severe bone marrow aplasia led to patient’s death shortly after initiation of antiretroviral treatment plus chemotherapy.

During the course of their disease, almost half of HIV / AIDS patients may develop different musculoskeletal complications including opportunistic bacterial or mycobacterial infections, diffuse reactive adenopathies and neoplasms [1, 2].
Representing an AIDS-defining condition, Kaposi’s sarcoma (KS) is histologically a proliferation of spindle-shaped neoplastic cells of vascular endothelial origin associated with a variable inflammatory infiltrate. After the introduction of highly active antiretroviral therapy (HAART), KS currently remains the most frequent tumour in HIV-infected patients worldwide, with an unpredictable but often aggressive behaviour. Progressive risk of developing KS is strongly associated with increasing degree of immunosuppression, particularly with CD4 count <200 [3-5].
Cutaneous KS usually appears as multiple irregularly shaped purple, red or brown skin lesions frequently with variable degrees of nodularity, accompanied by localized lymphedema. Occurring in 10-30% of patients, systemic disease includes dissemination to mucosal surfaces, lymph nodes, lungs and abdominal viscera. Conversely, involvement of bones or skeletal muscles by KS by osteolytic lesions and soft-tissue masses is exceptional, occurring either secondary to local extension or without neighbouring abnormalities [4-6].
Diagnostic imaging completes clinical evaluation in staging KS, since extensive superficial, gastrointestinal or other extra-nodal disease portends poor prognosis and is treated aggressively with HAART associated with systemic chemotherapy, whereas limited skin, oral and nodal KS should receive HAART alone [3, 4].
Radiologists should be familiar with the different musculoskeletal disease observed in HIV-AIDS patients, to propose a differential diagnosis list. Non-Hodgkin lymphoma (NHL) and KS account for the vast majority of neoplastic musculoskeletal involvement in this population [1, 2].
Largely requested to investigate possible opportunistic complications, CT and MRI can identify extra-skeletal enhancing soft-tissue masses involving the skin, subcutaneous fat and muscles, and sometimes associated osseous involvement including cortical erosion, bone destruction, or marrow signal abnormalities [1, 7]. Significant overlap exists between tumours and some infections manifesting as more or less homogeneous soft-tissue density or MR signal intensity, so biopsy is often necessary for the final diagnosis [1, 2, 6].
When reviewing head and neck imaging studies, careful attention should be paid to the calvarium since it may harbour severe disease. Sometimes unexpected, abnormalities involving the superficial tissues may lead to diagnosis of systemic opportunistic conditions. Furthermore, as in this patient cross-sectional imaging allows precise quantification of disease extension which is often impossible clinically, plus assessment or exclusion of muscle or bone infiltration [7].