Lymphoma

• Lymphoma:

  • Group of malignancies which arise within the lymphatic system
  • Includes - lymph nodes, the spleen, the thymus and the bone marrow
  • Two main types of lymphoma - Hodgkin's lymphoma and non-Hodgkin's lymphoma
  • Third most common cancer in childhood
  • More common in teenager and young adults (15-24)
• Aetiology:

  • Results from genetic alterations which trigger the abnormal proliferation of lymphocytes
  • One of the key features which distinguish most lymphomas from leukaemia is that the malignant cells are mature lymphocytes, and they arise within sites outside of the bone marrow (e.g. lymph nodes). In contrast, leukaemia develops from immature blasts and arises within the bone marrow.
  • The way in which lymphoblastic lymphomas are distinguished from lymphoblastic leukaemia is the degree of bone marrow infiltration by blasts; <25% bone marrow involvement is lymphoma, while >25% is leukaemia. However, these are treated the same as acute lymphoblastic leukaemia (ALL)
• Hodgkin's lymphoma:

  • Characterised histologically by presence of Reed-Sternberg cells (giant multinucleated cells)
  • Smaller mononuclear cells, which arise from B lymphocytes
  • Most cases are classical Hodgkin's lymphoma
• Non-Hodgkin's lymphoma:

  • Majority of cases are high-grade lymphomas, often of B-cell origin
  • Burkitt's lymphoma is the most common
  • B-cell NHL usually affects lymph nodes in the abdomen but can also develop in the head and neck
  • T-cell NHL usually affects lymph nodes in the chest
  • Extranodal NHL develops in sites outside of the lymph nodes
• Risk factors:

  • Immunodeficiency - post transplants, ataxia telangiectasia, Nijmegan-Breakage syndrome, HIV, and immunosuppressant drugs
  • EBV infection
• Symptoms:

  • Commonly present with painless, progressive lymphadenopathy (weeks-months)
  • B symptoms - fatigue, drenching night sweats, fever, weight loss
  • Pruritus
  • Mediastinal involvement - dyspnoea, cough, chest pain
• Symptoms that indicate extranodal involvement (more common in NHL):

  • Bone marrow - symptoms of anaemia, infections, easy bruising/bleeding
  • Abdomen - bloating, early satiety, pain, absolute constipation and vomiting if obstructed
  • Retroperitoneal lymphadenopathy - urinary retention
  • Testicular swelling
  • Central nervous system - behavioural change, headache, vomiting, seizures
• Clinical findings:

  • Non-tender, firm, matted lymph nodes
  • Mediastinal mass - SVC obstruction, effusions, airway obstruction
  • Abdomen - splenomegaly, hepatomegaly, abdominal mass
  • Testicular mass
  • Neurological - weakness, sensory abnormalities, features of raised ICP
• Lymph nodes:

  • Hodgkin's - often cervical, supraclavicular, axillary
  • NHL - more rapidly growing bulky lymphadenopathy
• Investigations:

  • Lymph node biospy for diagnosis - excision biopsy. HL will show reed-sternberg cells
  • CXR - mediastinal mass
  • CT/MRI/PET - staging
• The Lugano classification is used to stage lymphoma

  Emphasises whether the affected nodes are above or below the diaphragm
• Management:

  • HL - chemotherapy and radiotherapy
  • NHL - chemotherapy, monoclonal antibodies, radiotherapy, stem cell transplant
  • Rituximab is a monoclonal antibody that targets B cells - risk of hepatitis and HIV reactivation
• Approximately 90% of patients with Hodgkin’s lymphoma and >90% of children with Non-Hodgkin’s lymphoma achieve remission.