Kaposi Sarcoma |
| In
high-income countries, the annual incidence of new pediatric cancer is
15 cases per 100,000 children under the age of 15, with leukemia being
the most common diagnosis. Children infected with human
immunodeficiency virus (HIV) have a higher rate of malignancy when
compared with children without HIV. Most children infected with HIV
reside in sub-Saharan Africa. Children with HIV have an estimated
100-fold increased risk of developing Kaposi Sarcoma or Non-Hodgkin
lymphoma. Kaposi sarcoma (KS) is associated with co-infection with human herpesvirus-8 (HHV-8) and is the most common HIV-associated malignancy worldwide and the most frequently diagnosed cancer in many African nations. KS is an inflammatory neoplasm of endothelial cell origin, probably a polyclonal proliferation of spindle cell latently infected by human herpesvirus-8, which often evolves into an oligoclonal/monoclonal disorder. Four epidemiological forms of KS exist: 1) Classic, affecting elderly men, 2) Endemic, affecting young adults with a rapidly lymphadenopathic course, 3) Epidemic KS in HIV-infected patients being the most common form of pediatric KS worldwide, and 4) Iatrogenic KS in medically immunosuppressed patients affecting the skin, mucosa, lymphatic system, and visceral organs. Herpesvirus-8 is the causative agent for all epidemiological forms of KS in all patients. Pediatric classic and iatrogenic KS are extremely rare. Biopsy of the KS lesion is required for definitive diagnosis. Histologic features include spindle-shaped cells, inflammatory infiltrates, and angioproliferation with erythrocyte extravasation. KS is staged according to the classification developed by the AIDS Clinical trials group Oncology Committee which stratifies patients based on tumor burden, immune status, and presence of any systemic symptoms. The main feature that differentiates the childhood form of KS from adult disease is clinical presentation with primarily bulging lymphadenopathy. The Lilongwe Pediatric KS Staging Classification stratifies four distinct groups based on clinical phenotype: 1) mild/moderate disease limited to cutaneous and oral mucosal involvement, 2) lymphadenopathic disease, 3) woody edema, and 4) visceral and/or disseminated cutaneous/oral disease. The clinical course of KS in children with the epidemic form frequently follows a more aggressive course, without cutaneous involvement but involving mucosa and visceral organs. They are younger, with a mean age of 8 years. The endemic form is even younger (6 years of age) presenting with generalized or localized lymphadenopathy with sparse mucosal or skin lesions. Pediatric patients with classic KS present with more rapidly progressive disseminated and aggressive cutaneous lesions, oftentimes with mucosal and lymph node involvement, and can be lethal within 1-2 years of presentation. The iatrogenic form of KS is of variable age depending on the time of immunosuppressive therapy post-transplantation, presenting with pancytopenia and lymphadenopathy to more widespread visceral or mucocutaneous-cutaneous involvement. For children with epidemic or iatrogenic KS, the most effective treatment requires correcting the underlying immunodeficiency. Treatment for endemic and classic forms of KS is targeted on the basis of localized or disseminated disease. Symptomatic localized lesions are oftentimes managed with local measures such as intralesional vinblastine, liquid nitrogen, laser therapy, localized radiotherapy, topical retinoic acid, or surgical resection. Multifocal, symptomatic, or disseminated disease is managed with systemic chemotherapy. Antiviral therapy can be considered for the prevention of (primary) HHV-8 infection and subsequent KS development with systemic chemotherapy. The prognosis of epidemic KS has greatly improved with the use of highly active anti-retroviral therapy (cART). Immunosuppression from HIV infection and transplantation is associated with higher mortality risks. Positive outcomes in pediatric KS have been achieved in cohorts treated with chemotherapy and cART. Long-term survival is possible for pediatric KS in low-resource settings. References: 1- Rees CA, Keating EM, Lukolyo H, et al: Mapping the Epidemiology of Kaposi Sarcoma and Non-Hodgkin Lymphoma Among Children in Sub-Saharan Africa: A Review. Pediatr Blood Cancer. 63(8):1325-31, 2016 2- Jackson CC, Dickson MA, Sadjadi M, et al: Kaposi Sarcoma of Childhood: Inborn or Acquired Immunodeficiency to Oncogenic HHV-8. Pediatr Blood Cancer. 63(3):392-7, 2016 3- Schneider JW, Dittmer DP: Diagnosis and Treatment of Kaposi Sarcoma. Am J Clin Dermatol. 18(4):529-539, 2017 4- Kamiyango W, Villiera J, Silverstein A, et al: Navigating the heterogeneous landscape of pediatric Kaposi sarcoma. Cancer Metastasis Rev. 38(4):749-758, 2019 5- Campbell LR, El-Mallawany NK, Slone JS, et al: Clinical characteristics and successful treatment outcomes of children and adolescents with Kaposi sarcoma in Southwestern Tanzania. Pediatr Hematol Oncol. 39(1):28-47, 2022 6- Silverstein A, Kamiyango W, Villiera J, et al: Long-term outcomes for children and adolescents with Kaposi sarcoma. HIV Med. 23(2):197-203, 2022 |
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