Lymphomas

Published on 06/06/2015 by admin

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Last modified 06/06/2015

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56 Lymphomas

Lymphomas are malignant neoplasms of the lymphoid tissue and include Hodgkin’s lymphoma (HL) and non-Hodgkin’s lymphoma (NHL). They are the third most common type of pediatric cancer after leukemia and malignant brain tumors. In the United States, approximately 1700 children and adolescents younger than the age of 20 years are diagnosed with lymphomas each year. This is roughly 15% of the malignancies diagnosed in this age group. This chapter focuses on the presentation, diagnosis, evaluation, and management of children and adolescents with HL and NHL.

Hodgkin’s Lymphoma

Etiology and Pathogenesis

HL is a B-cell malignancy that affects the reticuloendothelial and lymphatic systems. In addition, HL can affect other organ systems including the lungs, bone marrow, bone, liver, and rarely the central nervous system (CNS). The World Health Organization classification divides HL into classical HL (nodular sclerosis, lymphocyte rich, mixed cellularity, and lymphocyte depleted), which accounts for 90% of cases, and nodular lymphocyte predominant HL.

Previous epidemiologic studies suggest that the etiology of HL may be multifactorial and that environmental, genetic, and immunologic factors play a role in the development of the disease. Several studies have documented a link between HL and Epstein-Barr virus (EBV). The idea of this association was first proposed in 1966, and through modern molecular study techniques, it has been found that EBV DNA is expressed in the Hodgkin and Reed-Sternberg cells of 50% and 95% of the cases of HL in developed and developing countries, respectively. EBV is mostly associated with the mixed cellularity type of HL, shows a male predominance, and is more frequent in patients younger than 10 years of age.

Clustering of HL in families suggests a genetic predisposition to HL, with an increased incidence especially among same-sex siblings, monozygotic twins, and parent–child pairs. There is a three- to ninefold increased risk of HL among family members of patients affected by the disease, which leads to the hypothesis that at least a small proportion of cases are inherited.

Clinical Presentation

The clinical presentation of HL can be varied but in most cases is asymptomatic. Approximately 70% to 80% of patients present with firm, rubbery, painless cervical lymphadenopathy. Often, patients will have been placed on antibiotics for presumed adenitis without improvement in the lymphadenopathy. Sixty percent of patients have mediastinal disease and may present with cough, chest pain, shortness of breath, orthopnea, or superior vena cava (SVC) syndrome. However, patients can also have mediastinal involvement without any symptoms. It is therefore important to image this area for disease before any diagnostic procedures given the risk of sedation or anesthesia in this setting. Cytokine production by Hodgkin and Reed-Sternberg cells is believed to be responsible for many of the nonspecific systemic symptoms of HL commonly seen at diagnosis, including fatigue, weight loss, pruritus, urticaria, and anorexia.

Approximately 30% of patients present with at least one constitutional, or B, symptom. These include unexplained fevers of greater than 38°C for at least 3 days, unexplained weight loss of at least 10% within the preceding 6 months before diagnosis, and drenching night sweats. These symptoms are indicative of more advanced disease and have prognostic implications for the patient. The presence of B symptoms often places the patient in a higher risk group category for the purpose of determining appropriate treatment.

Physical examination of any patient suspected of having HL should include a thorough evaluation of all lymph node chains; the presence of hepatosplenomegaly; and signs of bone marrow involvement, including bruising, petechiae, and pallor.

The differential diagnosis for HL includes various infections, other malignancies, and other causes of lymphadenopathy (Table 56-1).

Table 56-1 Differential Diagnosis of Hodgkin’s and Non-Hodgkin’s Lymphoma

  Hodgkin’s Lymphoma Non-Hodgkin’s Lymphoma
Infections

Malignancies Other

ALL, acute lymphoblastic leukemia; AML, acute myelogenous leukemia; CMV, cytomegalovirus; EBV, Epstein-Barr virus.

Evaluation and Staging

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