Description

B lineage malignant lymphoid neoplasm. Typically presents with painless lymphadenopathy, often cervical (70–80%) or supraclavicular (25%). Mediastinal mass present in 50%. Constitutional symptoms (e.g., fatigue, fever, night sweats, weight loss, cough, pruritus) may or may not be present. Constitutional symptoms sometimes precede development of lymphadenopathy.

Epidemiology

• Represents 7% of childhood cancer
• 11.7 cases/million/y age <20 years
• Most common cancer for ages 15 to 19 years
• Rarely seen in children age <5 years
• M > F age <15 years
• F > M age 15 to 19 years
• Bimodal age distribution in adults: early peak mid/late 20s; late peak > age >50 years

Risk Factors

• Few known risk factors include the following:
  • Immune deficiency (e.g., HIV infection)
  • Autoimmune disorders
  • Lower socioeconomic status for childhood form (age 14 years or younger)
  • Higher socioeconomic status for young adult form
• Decreased risk if
  • Multiple older siblings
  • Exposure to common infections in preschool

Pathophysiology

• Reed-Sternberg cells, a clonal population of large binucleate cells arising from B cells, are the malignant cells in HL. Surface antigen expression includes CD30 but not CD20.
• Only 1% of cells in involved nodes are Reed-Sternberg cells and morphologic variants; the rest are inflammatory cells: lymphocytes, macrophages, fibroblasts, plasma cells, eosinophils.
• Two clinically distinct subtypes of HL recognized:
  • Classical HL (90–95% of cases)
    • Nodular sclerosing
    • Mixed cellularity
    • Lymphocyte depleted
    • Lymphocyte rich
  • Nodular lymphocyte predominant (5–10% of cases; treated differently from classical HL. See National Comprehensive Cancer Network (NCCN) guidelines for treatment recommendations.)

Etiology

• Cause unknown
• Association between Epstein-Barr virus (EBV) infection and HL: 20–50% of patients with classical HL have monoclonal or oligoclonal proliferation of EBV-infected cells.