Definition:
Lymphomas are malignant neoplasms of the lymphoid system involving clonal proliferation of lymphocytes, which can arise anywhere lymphoid tissue exists (lymph nodes, spleen, thymus, GI tract, skin, etc.). They are classified into:
- Hodgkin Lymphoma (HL)
- Non-Hodgkin Lymphoma (NHL)
Etiology / Risk Factors:
Hodgkin Lymphoma (HL):
- Clonal B-cell neoplasm
- Associated with Epstein-Barr Virus (EBV)
- Originates from B-cells that fail to express immunoglobulin but escape apoptosis
- Risk factors:
- Infectious mononucleosis (EBV)
- Immunosuppression
- Young adults or elderly
Non-Hodgkin Lymphoma (NHL):
- B-cell (70%) or T-cell (30%) origin
- Clonal expansion at various maturation stages
- More common than HL
- Risk factors:
- Immunodeficiency (HIV/AIDS, transplant recipients)
- EBV (esp. in endemic Burkitt lymphoma)
- Idiopathic in many cases
Pathogenesis:
- HL:
- Hallmark = Reed–Sternberg cells (large, bi/multinucleated cells with prominent nucleoli)
- Derived from germinal center B-cells
- Inflammatory background (eosinophils, lymphocytes, plasma cells)
- NHL:
- Neoplastic transformation of B or T lymphocytes
- Diverse subtypes with variable aggressiveness
- Frequently affects extranodal sites (GI, CNS, skin)
Clinical Features:
General:
- Painless lymphadenopathy (common initial symptom)
- Systemic 'B' symptoms:
- Fever
- Night sweats
- Unintentional weight loss >10%
- Fatigue, anorexia
- Hepatosplenomegaly
HL:
- Typically begins in single axial node group (e.g., cervical, mediastinal)
- Contiguous spread
- Extranodal involvement is rare
- More common in younger adults
NHL:
- Often multiple peripheral nodes
- Non-contiguous spread
- Extranodal involvement is common (e.g., GI tract, lungs, CNS, skin, testes)
- May present with local symptoms (e.g., bowel obstruction, neurological signs)