In children there are two AIDS-defining malignancies: Kaposi sarcoma (KS) and B-cell lymphoma (including primary central nervous system (CNS) lymphoma). These HIV-related malignancies (HIVRM) most frequently occur when the CD4 count is low, and far less frequent in children than in adults.

Globally, most children with HIV live in sub-Saharan Africa, thus it is expected that most pediatric cases of HIVRM will occur in Africa. Because of the introduction of antiretroviral therapy (ART), increased education of the population, and reduced transmission of infection from mother to child, it is expected that the number of newly diagnosed children with HIVRM will reduce considerably in the coming years.

Kaposi sarcoma is a mesenchymal tumor of multifactorial origin, which involves blood and lymphatic vessels. There are four recognized forms :

The development of the epidemic form of KS is attributable to the presence of HHV8, also known as the Kaposi sarcoma-associated virus as well as cytokine-induced growth in a child with immunosuppression. Although necessary, the mere presence of HHV8 is not sufficient for the development of KS. The seroprevalence of HHV8 among the general population varies geographically. The route of transmission is thought to include vertical and horizontal transmission, blood transfusion, and intravenous drug use as well as organ- or bone marrow transplantation. In endemic areas, the infection is probably acquired in childhood from seropositive family members; the seroprevalence rates increase with age, reaching as high as 80 %.

This is the most common presentation of disease in children, which tends to occur in younger children with relatively higher CD4 counts. This is likely because of a recent HHV8 infection with rapid progression to malignancy. Lymph node involvement may be the sole characteristic present. Massive lymph node enlargement and lymphedema may develop.

Cutaneous lesions vary in size, characteristics, and number, ranging from a few isolated lesions to widespread cutaneous involvement. The lesions may be small (<1 cm) macular/papular lesions or large confluent nodules (≥10 cm). They appear to be dark, and almost black in dark-skin patients, and may also appear violaceous and hairy. This may occur linearly and symmetrically along skin tension lines, or may be randomly distributed. Although usually painless and non-pruritic, they may become painful. There may be associated edema. Plaque-like lesions also occur, often as a coalescence of multiple nodules. These lesions occur on the thighs, calves or feet soles and may be exophytic and fungating with breakdown of the overlying skin. These may ulcerate, bleed, or develop secondary bacterial infection, and lymphedema is often present (Fig. 20.7).

Disease involving the oral cavity may be the initial presentation of KS. Oral lesions range from flat, red to violet papules to exophytic, ulcerative nodules. Lesions most commonly occur on the palate, oropharynx, and gingivae, but may involve any mucosal surface, i.e., the tongue, tonsillar pillars, mouth floor, pharynx, or trachea. This may also become painful, bleed, or ulcerate if traumatized during normal chewing, and may become secondarily infected. If large, they may interfere with nutrition, speech, and breathing.

Laryngeal involvement may occur; the most common site being the epiglottis. Presenting symptoms of laryngeal KS may include pain, bleeding, dysphagia, speech abnormalities, and airway compromise.

KS involving the sclera is commonly missed. In the early stages of disease, it may appear as painless conjunctival injection, particularly at the canthi of the eyes, and is commonly treated as conjunctivitis. Red or purplish nodular lesions may also be seen involving the tarsal conjunctiva.

Visceral presentation includes pulmonary or gastrointestinal involvement and rarely other organs.

Pulmonary KS must be excluded in HIV-infected patients with respiratory symptoms or abnormal CXR findings, especially in the presence of cutaneous KS. Any intrathoracic structure may be involved, including lymph nodes, tracheobronchial tree, pulmonary parenchyma, and pleura. Common presenting symptoms include coughing, hemoptysis, shortness of breath, pleuritic chest pain, and fever. Physical examination may be normal or nonspecific.

Gastrointestinal involvement may occur in the absence of cutaneous disease and may in itself be asymptomatic. Symptoms include nausea, vomiting, abdominal pain, weight loss, upper and lower gastrointestinal bleeding or that of intestinal obstruction.