Leukemia Diagnosis

Acute Lymphoblastic Leukemia (ALL)

• Signs of mediastinal compression: respiratory distress, typically seen in adolescent boys with T-cell ALL
• Signs of increased intracranial pressure: papilledema, retinal hemorrhages, and cranial nerve palsies
• Laboratory diagnosis:
  • Hemogram shows anemia, thrombocytopenia, and total leucocytic count < 10,000/mm3 in most patients
  • Bone marrow examination shows > 25% homogeneous population of lymphoblasts
  • Lumbar puncture examines CSF for malignant cells
  • Serum uric acid, liver function tests, and renal function tests before onset of treatment
  • Cytogenetic studies detect chromosomal abnormalities influencing prognosis and therapy choice
  • Immunophenotyping
  • Chest X-ray for mediastinal lymph nodes in T-cell leukemia

Differential Diagnosis

• Acute myelogenous leukemia
• Tumors that infiltrate the bone marrow (neuroblastoma, lymphomas, retinoblastoma)
• Diseases of bone marrow failure (aplastic anemia)
• Infectious mononucleosis

Treatment of Standard Risk ALL

• The single most important prognostic factor is treatment
• Important prognostic factors: age (1-10 years), initial leukocytic count, and speed of response to treatment
• Drug therapy includes 3 phases + intrathecal therapy
  • Induction of remission (4 weeks): vincristine, dexamethasone or prednisone, L-asparaginase, and intrathecal cytarabine or methotrexate

Neuroblastoma

• Embryonal tumor derived from neural crest cells that form the adrenal medulla and sympathetic nervous system
• Third most common solid tumor of childhood
• Age incidence: 90% are less than 5 years
• Etiology: unknown, may be attributed to environmental and genetic factors
• Pathology: ranges from undifferentiated small round cells to tumors containing mature ganglion cells

Clinical Manifestations

• Primary sites: adrenal gland, abdomen, chest, pelvis, and neck
• Diverse presentations due to different site of origin:
  • Abdominal mass (commonest presentation)
  • Posterior mediastinal mass
  • Proptosis (unilateral or bilateral)
  • Multiple skin nodules in infancy
  • Spinal cord compression
  • Pancytopenia, arthritis, and bone pain
  • Cervical neuroblastoma
  • Paraneoplastic syndromes

Investigations

• Plain X-ray: may show calcification in abdominal neuroblastoma
• Ultrasound scan, CT, or MRI: define primary tumor extent
• Bone marrow: multiple site aspirates necessary to exclude infiltration
• Urinary catecholamines: elevated in at least 90% of patients at diagnosis
• Biopsy: routine histology, immunocytochemistry, and molecular/genetic study required

Differential Diagnosis

• Wilms tumor
• Leukemia

Treatment

• Complete surgical excision is the initial treatment of choice for localized neuroblastoma
• Combination chemotherapy for advanced diseases
• Delayed resection of primary tumor after numerous courses of chemotherapy
• Chemotherapeutic agents: vincristine, cyclophosphamide, doxorubicin, cisplatin, and etoposide
• Radiation therapy for primary tumor bed and area of metastatic disease

Prognosis

• Affected by age of patient at presentation
• Stage of the disease
• Primary site
• Presence or absence of metastasis
• Cytogenetics and histopathology