Hodgkin Lymphoma: Types and Diagnosis

• Lymphoma is a malignant neoplasm of lymphoid origin.
• It typically results in a solid tissue mass, like lymphadenopathy, or an extra nodal mass.
• Examples of extra nodal masses include tumors in the brain or intestine.

WHO Classification of Lymphoid Neoplasms

• Lymphoid neoplasms are classified into Non-Hodgkin lymphoma and Hodgkin lymphoma.
• Non-Hodgkin lymphoma is further divided into B cell lymphoma and T cell/NK cell lymphoma.

Hodgkin Lymphoma (HL)

Intended Learning Objectives

• The learning objectives include describing the epidemiology, etiology, pathogenesis, types, clinical manifestations, investigations, diagnostic criteria, RS cells, variants of RS cells, prognosis, and treatment of HL.
• Also, enumerate the important differences between HL and NHL.

Epidemiology

• HL is one of the most common cancers of young adults and adolescents.
• HL is less frequent than NHL.
• Peak incidence occurs in two age groups: 15-35 years and 50-70 years).
• HL incidence is higher in males than in females.

Etiology

• The exact cause of HL is unknown.
• Epstein-Barr Virus infection might be involved.
• Individuals with Human Immunodeficiency Virus (HIV) have a higher incidence of HL.
• A possible genetic predisposition exists.
• Siblings of an affected individual have a 3- to 7-fold increased risk of developing the disease.

Pathophysiology

• HL is characterized by the presence of Reed-Sternberg cells (RS cells) or their variants.
• Reed-Sternberg cells are the neoplastic cells in HL.

Reed-Sternberg Cells (RS Cells)

• RS cells originate from germinal center B cells or post-germinal center B cells.
• RS cells are large/giant cells with a diameter of ≥45 µm.
• RS cells contain multiple nuclei or a single nucleus, with multiple nuclear lobes
• RS cells have a large nucleolus about the size of a small lymphocyte, 5–7 µm in diameter
• RS cells exhibit an "Owl's eye appearance".
• Immunohistochemistry markers for RS cells are CD15 and CD30.

Clinical Presentation

• Asymptomatic lymphadenopathy is common in Hodgkin Lymphoma.
• Lymphadenopathy is peripheral, progressive, and painless.
• B symptoms occur in 40% of patients
• B symptoms include unexplained weight loss of more than 10% of total body weight, unexplained fever, and night sweats.
• Chest pain, cough, and shortness of breath are possible due to a large mediastinal mass or lung involvement.

Natural Course of the Disease

• HL usually starts with a nodal disease.
• Progresses to contiguous groups of lymph nodes.
• Then spreads to the spleen, liver, bone marrow, and other tissues.

General Microscopic Features

• Normal histologic architecture of the lymph node is lost.
• Presence of Reed-Sternberg (RS) cells.
• Infiltration of inflammatory cells such as lymphocytes, plasma cells, neutrophils, eosinophils, and histiocytes.

Classification of HL

• Classical Hodgkin Lymphoma (cHL) includes Nodular Sclerosis HL, Mixed Cellularity HL, Lymphocyte-Rich HL, and Lymphocyte Depletion HL.
• Nodular lymphocyte predominance Hodgkin Lymphoma.

Classical Hodgkin Lymphoma: Nodular Sclerosis Type

• Most common type of HL.
• Characterized by lacunar variant RS cells and the presence of collagen bands.
• Occurs with equal frequency in males and females.
• Has an excellent prognosis.

Classical Hodgkin Lymphoma: Lymphocyte Depletion Type

• The least common form of classical Hodgkin Lymphoma.
• Has a less favorable prognosis.

Investigations for Diagnosis and Staging

• Serological tests include CBC, ESR, and HIV testing.
• Imaging studies include X-rays, computed tomography (CT) scans, and positron emission tomography (PET) scans.
• Biopsy of lymph node/mass or bone marrow.

Staging of HL

• Ann Arbor classification is used for HL staging.
• Staging determines prognosis.
• Cure rate of patients with stages I and IIA is close to 90%.
• Staging guides therapy.

Treatment

• HL is a curable malignancy.
• Modalities include radiation therapy, chemotherapy, and hematopoietic stem cell transplantation.

Key Differences Between HL and NHL

• HL more often localized to a single axial group of nodes (cervical, mediastinal, para-aortic), while NHL more frequent involvement of multiple peripheral nodes.
• HL has an orderly spread by contiguity, whereas NHL spreads noncontiguously.
• Mesenteric nodes and Waldeyer ring are rarely involved in HL but are commonly involved in NHL.
• Extra-nodal presentation is rare in HL but common in NHL.

Hodgkin Lymphoma (HL) is a common cancer in young adults, characterized by solid tissue masses. HL is classified based on epidemiology, etiology, pathogenesis and clinical manifestation. Diagnosis involves identifying Reed-Sternberg (RS) cells and understanding HL's subtypes.