Malignant diseases, such as leukemia, lymphoma, neuroblastoma, Ewing’s sarcoma, and bone tumors, frequently present as bone or joint pains. Such patients may be mistakenly diagnosed as having rheumatoid arthritis, lupus, Lyme disease, or other rhuematic diseases. Clinical features that are common to both rheumatic and malignant diseases and those that suggest the presence of a malignant disorder are listed in Display 64-1.

Most cases of bacterial lymphadenitis in children respond to oral antibiotics, and viral lymphadenitis usually subsides in 2 to 3 weeks. Thus, an enlarged lymph node measuring greater than 1 cm and persisting and enlarging for more than 2 to 3 weeks requires further evaluation to determine the etiology. A “shotty” lymph node that diminishes in size between intercurrent illnesses probably does not qualify for workup. Initial screening studies should include the following:

Figure 64-1 outlines a plan for investigation of lymphadenopathy. A markedly elevated ESR is usually suggestive of a systemic illness, probably other than a viral infection.

In neonates, more than 85% of abdominal masses are benign. Renal abnormalities, mainly hydronephrosis and cystic dysplasia of kidneys, account for more than 50% of all abdominal masses. In infants and children, fewer than half of all abdominal masses are malignant, and most of the solid renal tumors are Wilms’ tumors. Neuroblastomas account for most of the nonrenal solid tumors in the abdomen. Other abdominal tumors include lymphomas and rhabdomyosarcomas. Common pelvic tumors include rhabdomyosarcomas and ovarian tumors. Most of the cystic lesions are benign.

An ultrasound examination is an ideal screening test, because it can differentiate cystic from solid lesions and requires no contrast or sedation. In addition, ultrasound can detect the presence of a tumor thrombus in the renal vein or inferior vena cava in patients with Wilms’ tumor. Computed tomography (CT) scan is superior to sonogram in demonstrating retroperitoneal structures, including lymph nodes. Optimal CT imaging requires oral and intravenous contrast, however, and young children need sedation to prevent movement artifacts.

The differential diagnosis of mediastinal masses is outlined in Display 64-2. Children with anterior mediastinal masses often have tracheal compression and present with wheezing or respiratory distress. These symptoms may be exacerbated in the supine position and mistaken for asthma.

Anterior mediastinal masses may also compress the superior vena cava, causing some or all manifestations of superior vena cava syndrome. These include orthopnea, headache, dizziness, fainting, plethoric facial swelling, jugular venous distension, papilledema, and pulsus paradoxus.

It is sound clinical practice to obtain a CT scan of the chest in cases of large pleural effusion that may be masking a mediastinal mass. Confirmation of diagnosis requires examination of pleural fluid, bone marrow aspirate study, or biopsy of an enlarged cervical lymph node or the mediastinal mass itself.

Brain tumors are the most common solid tumors in children. The possibility of a brain tumor should be considered in any child with unexplained neurologic symptoms or signs. The presenting symptoms and signs of brain tumors may be localizing in nature, such as hemiparesis of hemispheric lesions. Nonlocalizing symptoms are secondary to increased intracranial pressure and include irritability, lethargy, headache, vomiting, and behavioral changes. A more complete list of signs and symptoms of childhood brain tumors is given in Display 64-3.

Children who complain of back pain or weakness of lower extremities should be promptly evaluated for spinal cord compression. MRI is the preferred imaging study because it can demonstrate an epidural mass and any intraparenchymal
spinal cord lesion or compression of the cauda equina. Although rare, neuroblastomas and lymphomas can present with spinal cord compression.

In an otherwise well-looking child, single cytopenia (anemia, thrombocytopenia, or neutropenia) is unlikely to be caused by leukemia.

When bacterial infections cause very high white blood cell (WBC) counts (leukemoid reaction), there is a high percentage of neutrophils and bands. In leukemia, however, a high WBC count is always associated with a very low percentage of neutrophils, because the increase in the WBC count is due to the presence of leukemic cells (blasts) in the peripheral blood.

A provisional diagnosis of cancer can often be made, or at least strongly suspected, by the primary care provider from the results of the preliminary tests, including certain imaging studies. The definitive diagnosis of cancer, however, frequently requires confirmatory studies, such as bone marrow aspirate study in the case of leukemia or histopathologic examination of the tumor tissue in solid tumors. In addition to routine morphologic examination of the specimen by light microscopy, special studies, such as immunostains, cytogenetics, flow cytometric analysis of tumor-specific antigens, cell ploidy, and molecular biologic studies, are often essential for the definitive diagnosis and assessment of prognosis. These confirmatory tests should be done at the referral center under the direction of a pediatric oncologist.

The primary care provider can play a significant role in the treatment of the child with cancer. This requires developing a close working relationship with the pediatric oncologist. In some settings, the provider can coparticipate in the patient’s cancer therapy, administering selected chemotherapy that has been prescribed by the oncologist. Examples of such agents include vincristine, cytarabine, and dactinomycin. These agents are administered by slow intravenous push through a central venous catheter. In addition, the practitioner may also give intramuscular injections of L-asparaginase and subcutaneous injections of cytosine arabinoside prescribed by the oncologist. These two drugs are commonly used in the treatment of acute lymphoblastic leukemia (ALL). Such participation by the primary provider vastly improves the quality of life for patients and parents by enabling them to receive treatment in a smaller, more familiar setting and by decreasing their visits to an often more distant cancer center.

A host of factors, including neutropenia, low immunoglobulin levels, impaired mucosal integrity, and indwelling catheters, compromise the immunity of children with cancer. Lowered immunity makes such children susceptible to serious infections. Gram-negative organisms such as Pseudomonas aeruginosa, Escherichia coli, and Klebsiella pneumoniae are a particular threat to the neutropenic host. Staphylococcal infections, Pneumocystis carinii pneumonia, and cryptococcal meningitis occur in non-neutropenic hosts as well. Coagulase-negative staphylococci are common pathogens in patients with indwelling central lines. Life-threatening

complications include gram-negative sepsis, pneumonias, and disseminated fungal infections.

Most of the infections in children with cancer are caused by endogenous organisms. Attempts to sterilize the gastrointestinal tract with broad-spectrum antibiotics are not effective in reducing the incidence of infections. In addition, their use may increase the emergence of resistant organisms. Simple hand washing by all hospital personnel and visitors is the most effective prevention against hospital-acquired infections. Strict reverse isolation does not usually add much to hand washing in the prevention of infections. Patients should avoid eating any uncooked food, including fresh vegetables and fresh fruits. High-efficiency particulate air filters may be effective in preventing Aspergillus infections (Freifeld, Walsch, & Pizzo, 1997). Chapter 54 provides a discussion about these filters.

Children on cancer chemotherapy are frequently anemic and thrombocytopenic from either chemotherapy or their underlying disease. In most chemotherapy regimens, the nadirs for platelet counts and WBC counts occur 7 to 10 days from the first day of chemotherapy. The counts begin to rise about 10 to 14 days from the completion of therapy. Decrease in the hemoglobin levels is more gradual, because the lifespan of normal red cells is 90 to 120 days.

Red cell transfusions are usually given when the hemoglobin is less than 8 g/dL (hematocrit less than 24%), unless the child is recovering from the chemotherapy and the hemoglobin is expected to rise. When the hemoglobin level falls below 7 g/dL, patients usually have symptoms of anemia, including tiredness, headaches, anorexia, and lack of energy. Transfusion of red cells thus is indicated. One unit of packed red cells (PRBC) is approximately 300 mL. A usual volume used is 15 mL of PRBC per kg of body weight, which will raise the hematocrit by 12% (eg, from 20% to 32%).

Platelet transfusions are indicated when the platelet count is less than 20,000/mm³. If there is clinical bleeding (eg, epi-staxis or gastrointestinal bleed), any platelet count less than 50,000/mm³ warrants transfusion. One unit of random platelets (50 mL) per 5 kg of body weight will raise the platelet count by 50,000/mm³. One unit of single donor
platelets (approximately 300 mL) is equal to 6 U of random platelets. Single donor units are preferred for those who receive multiple transfusions.