What is an overview of lymphoma, including its classification, clinical presentation, diagnostic workup, and management?

Overview of Lymphoma

Lymphoma is a heterogeneous group of malignant neoplasms arising from clonal proliferation of lymphocytes, broadly classified into two major categories: Hodgkin lymphoma (HL) and non-Hodgkin lymphoma (NHL), with over 90 distinct subtypes requiring tissue biopsy for definitive diagnosis and risk-stratified treatment approaches that significantly impact survival. 1, 2, 3

Epidemiology and Incidence

Lymphoma represents a significant oncologic burden with distinct epidemiologic patterns:

• Hodgkin lymphoma occurs at an incidence of 2-3 per 100,000 annually in Western countries, with a characteristic bimodal age distribution peaking in the third decade and again after age 55 1, 2
• Non-Hodgkin lymphoma is substantially more common, with approximately 82,000 new cases diagnosed annually in the United States, representing the seventh leading site of new cancer cases 4, 3
• NHL is approximately 4 times more common than HL 5
• Major modifiable risk factors include tobacco use and obesity, with genetic, infectious (including HIV/EBV), and inflammatory etiologies also contributing 3

Classification Systems

Hodgkin Lymphoma Classification

HL is uniquely characterized by malignant Hodgkin-Sternberg cells or lymphocytic and histiocytic (L&H) cells representing only 0.1-1% of the tumor population, surrounded by reactive inflammatory cells 1, 2. The WHO classification distinguishes:

1. Lymphocyte Predominant Hodgkin Lymphoma (LPHL) - 5% of cases

• Immunophenotype: CD15-/CD30-/CD20+
• More indolent course with tendency to recur
• Often presents in early stages 1

2. Classical Hodgkin Lymphoma (cHL) - 95% of cases 2

• Immunophenotype: CD15+/CD30+/CD20-
• Subtypes include:
  • Nodular sclerosing (most common)
  • Mixed cellularity
  • Lymphocyte rich
  • Lymphocyte depleted 1

Non-Hodgkin Lymphoma Classification

NHL encompasses diverse entities with distinct natural histories, requiring precise classification through morphology, immunohistochemistry, flow cytometry, and molecular studies 6, 7. Major subtypes include diffuse large B-cell lymphoma, follicular lymphoma, Burkitt lymphoma, chronic lymphocytic leukemia/small lymphocytic lymphoma, and various T-cell lymphomas 4, 8.

Clinical Presentation

Common Presenting Features

Painless lymphadenopathy is the hallmark presentation, occurring in over 60% of HL patients, most commonly involving cervical lymph nodes 1, 9. The clinical spectrum varies significantly:

Hodgkin Lymphoma:

• Prominent B-symptoms (fever >38.3°C, drenching night sweats, unexplained weight loss >10% over 6 months) 1, 2
• Pruritus and alcohol-induced pain (specific to HL) 6
• Mediastinal involvement common in nodular sclerosing subtype

Non-Hodgkin Lymphoma:

• Abdominal signs and symptoms more prominent 5
• Extranodal involvement more frequent (spleen, liver, bone marrow, lung, GI tract) 1
• Systemic symptoms occur in more advanced stages 3

Common symptom frequencies in lymphoma patients include: fever (72%), weight loss (59.7%), vomiting (54.8%), abdominal pain (43%), and headache (26.3%) 9. Physical findings include splenomegaly (86%), anemia (84.4%), hepatomegaly (79%), and jaundice (31.2%) 9.

Diagnostic Workup

Tissue Diagnosis - Mandatory First Step

An excisional or incisional lymph node biopsy is absolutely required for initial diagnosis - fine-needle aspiration alone is inadequate and should never be used as the sole diagnostic method 2, 4, 6. Core needle biopsy may be acceptable when excisional biopsy is not feasible, but a nondiagnostic sample mandates proceeding to excisional biopsy 6.

The pathologic evaluation must include:

Essential components:

• Hematopathology review with paraffin block representative of tumor 4
• Immunohistochemistry panel: CD20, CD3, CD5, CD10, BCL2, BCL6, cyclin D1, CD21, CD23 4
• Flow cytometry: kappa/lambda, CD19, CD20, CD5, CD23, CD10 4

Additional testing for specific scenarios:

• FISH for t(14;18), BCL6 rearrangements, MYC rearrangements (poor prognosis indicators) 4, 10
• Molecular analysis for antigen receptor rearrangements 4
• TP53 mutation detection (mandatory before first treatment in CLL/SLL) 11
• IGHV mutational status (guides prognosis and treatment selection) 11

Staging Evaluation

Comprehensive staging is mandatory and includes:

Imaging:

• PET-CT is the standard for FDG-avid lymphomas (most HL and aggressive NHL), improving accuracy over CT alone for nodal and extranodal sites 6, 10
• CT of neck, chest, and abdomen mandatory 2
• MRI for CNS involvement assessment when clinically indicated 6

Laboratory investigations:

• Complete blood count, ESR, C-reactive protein 2
• Comprehensive metabolic panel including LDH, alkaline phosphatase, liver enzymes, albumin 2
• Bone marrow aspiration and biopsy (though PET-CT may be adequate for determining bone marrow involvement) 2, 6

Staging laparotomy and splenectomy are no longer recommended 1, 2. Liver biopsy should be restricted to cases with elevated alkaline phosphatase or specific clinical suspicion 1.

Staging Systems

Ann Arbor/Cotswolds Classification (modified as Lugano classification) remains the foundation 1, 6:

For Hodgkin Lymphoma, risk stratification includes:

• Early favorable: Stage I-II without risk factors
• Early unfavorable: Stage I-II with risk factors (large mediastinal mass >1/3 horizontal chest diameter, extranodal disease, ESR >50 with B symptoms or >30 without, ≥3 involved lymph node areas)
• Advanced: Stage III-IV, or IIB with large mediastinal mass or extranodal involvement 1

Prognostic indices are increasingly important for risk stratification:

• International Prognostic Index (IPI) for LBCL 10
• CNS-IPI for CNS relapse risk assessment 10

Management Principles

Hodgkin Lymphoma Treatment

Early Favorable Disease: Two cycles of ABVD (doxorubicin/bleomycin/vinblastine/dacarbazine) followed by 30 Gy involved-field radiotherapy is the standard of care, achieving tumor control and overall survival exceeding 85-90% at 5 years 1, 2. This combined modality approach substantially reduces relapses compared to radiotherapy alone 1.

Early Unfavorable Disease: Four cycles of ABVD followed by 30 Gy involved-field radiotherapy, with similar excellent outcomes 1.

Advanced Stage Disease:

• Patients ≤60 years: Eight cycles of ABVD or eight cycles of BEACOPPescalated (bleomycin/etoposide/doxorubicin/cyclophosphamide/vincristine/procarbazine/prednisone) followed by 30 Gy radiotherapy for residual masses >1.5 cm 2
• Patients >60 years: ABVD preferred due to higher toxicity of escalated regimens 2

Lymphocyte Predominant HL (Stage I): 30 Gy involved-field radiotherapy alone is adequate; rituximab is an option for relapsed disease 1.

Relapsed/Refractory Disease: Salvage regimens (DHAP or IGEV protocols) followed by autologous stem cell transplantation for chemosensitive disease 2.

Non-Hodgkin Lymphoma Treatment

Treatment varies dramatically by subtype, reflecting the biological heterogeneity:

Diffuse Large B-Cell Lymphoma:

• First-line: R-CHOP (rituximab/cyclophosphamide/doxorubicin/vincristine/prednisone) or Pola-R-CHP (polatuzumab vedotin-based) depending on IPI scores 3, 10
• Primary mediastinal B-cell lymphoma: R-CHOP14 or DA-EPOCH-R without radiotherapy in complete responders 10
• Relapsed/refractory <1 year: CAR-T therapy is gold standard in second line 10
• Third line: CAR-T in CAR-T-naïve patients or bispecific antibodies 10

Follicular Lymphoma: Treatment approach depends on stage and risk factors, with options including rituximab-based regimens, bendamustine, and lenalidomide 4, 3.

Burkitt Lymphoma: Intensive chemo-immunotherapy regimens including anti-CD20 monoclonal antibodies, achieving 80-90% overall survival in young patients 12.

CLL/Small Lymphocytic Lymphoma:

• Del(17p)/TP53 mutation: Second-generation covalent BTK inhibitor indefinitely 11
• Without del(17p)/TP53 mutation, mutated IGHV: Time-limited BCL2 inhibitor combination preferred 11
• Unmutated IGHV: Either continuous BTKi or finite BCL2i therapy, individualized based on toxicity profiles and patient factors 11

Special Considerations

Elderly/Frail Patients: Geriatric assessment mandatory for patients ≥80 years or <80 with poor fitness; adapted regimens include R-miniCHOP or non-anthracycline regimens 10. Prephase corticosteroids improve performance status 10.

CNS Prophylaxis: Value remains uncertain; CNS-IPI scores and specific anatomical sites identify high-risk patients requiring MRI and CSF analysis 10.

Treatment Toxicities: Long-term surveillance required for cardiotoxicity, osteoporosis, immune dysfunction, neurocognitive impairment, endocrine dysfunction, neuropathy, secondary malignancies (lung, breast), and mental distress 3, 10.

Surveillance and Follow-up

Clinical examination recommended for 2 years post-treatment 10. PET-CT is critical for assessing treatment response using standardized criteria 6. Patients require:

• Management of long-term treatment side effects
• Age-appropriate cancer screenings
• Immunization updates: 13-valent pneumococcal conjugate vaccine followed by 23-valent pneumococcal polysaccharide vaccine at least 8 weeks later, plus age-appropriate vaccinations 3
• Household contacts should maintain current immunizations due to patient immunosuppression 3

Critical Pitfalls to Avoid

1. Never rely on FNA alone for initial diagnosis - this is inadequate and delays appropriate treatment 2, 4, 6
2. Do not perform staging laparotomy - this outdated procedure is no longer recommended 1, 2
3. Recognize that follicular lymphoma grade 3 with any area of DLBCL should be treated as DLBCL, not as indolent lymphoma 4
4. Do not delay treatment initiation - particularly in aggressive subtypes like Burkitt lymphoma where rapid proliferation demands urgent intervention 12
5. Ensure TP53 mutation testing before first treatment and at each relapse in CLL/SLL, as this fundamentally alters treatment selection 11