PA19.{1-3,5-6} | Lymphadenopathy & Lymphomas — Case Study

CLINICAL SCENARIO

A 22-year-old male college student presents with a 6-week history of painless, progressively enlarging cervical and supraclavicular lymph nodes, a mediastinal mass on chest X-ray, night sweats, low-grade fever, and a 6 kg weight loss over two months. You are the intern on call. This case integrates your understanding of lymphadenopathy, the four major differentials, biopsy decision-making, and the histopathological diagnosis of Hodgkin lymphoma.

Section 1 — History & Initial Assessment (SDL1)

List the five most diagnostically important features in this patient's history and examination. For each feature, state what it tells you about the likely category of lymphadenopathy (reactive, infective/granulomatous, lymphoma, metastatic).

Guidance: Think about the age of the patient, duration and character of node enlargement, constitutional B symptoms, and the anatomical distribution (cervical + mediastinal). Use the systematic framework from SDL1: location → consistency → duration → associated symptoms → patient demographics.

Section 2 — Building the Differential Diagnosis (SDL1, SDL2)

Construct a ranked differential diagnosis with four entries: (a) Reactive lymphadenopathy, (b) Tuberculous lymphadenitis, (c) Lymphoma, (d) Metastatic carcinoma. For each, list two features in this case that support it AND two features that argue against it.

Guidance: Be specific. 'Young age argues against metastasis' is better reasoning than 'doesn't fit the history.' For TB, consider the epidemiological context and SDL2's description of caseating granuloma — which features here make TB less likely as the primary diagnosis?

Section 3 — Biopsy Decision: Excision vs FNAC (SDL1, SDL2)

The surgical registrar suggests FNAC to get a quick answer. As the intern, you recommend excision biopsy instead. Write a 3–4 sentence argument justifying your recommendation, addressing: (a) what FNAC cannot reliably tell you about lymph node architecture, (b) why architectural information is essential for lymphoma diagnosis, and (c) in which specific scenario (other than this case) FNAC would be an acceptable first-line investigation.

Guidance: SDL1 describes the diagnostic limitations of FNAC versus excision biopsy. Lymphoma diagnosis depends on follicular versus diffuse architecture, capsular invasion, and Reed-Sternberg cell identification — none of which FNAC preserves. Mention that FNAC is acceptable for reactive nodes in young patients where lymphoma is very unlikely, or for rapid palliative triage.

Section 4 — Histopathological Interpretation (SDL3, SDL4)

The excision biopsy report reads: 'Effacement of nodal architecture with fibrous bands dividing the node into nodules. Background mixed inflammatory infiltrate with eosinophils, plasma cells, and lymphocytes. Scattered large binucleated cells with prominent 'owl-eye' nucleoli. Immunohistochemistry: CD15+, CD30+, CD45−, CD20−.' (a) Name the cell type responsible for the owl-eye appearance and its cell of origin. (b) State the WHO subtype of Hodgkin lymphoma this pattern represents. (c) Explain why CD15+/CD30+ with CD45−/CD20− is diagnostically critical.

Guidance: The Reed-Sternberg (RS) cell is the neoplastic cell; SDL4 covers its B-cell origin and why it paradoxically loses B-cell markers. Nodular sclerosis is the commonest HL subtype in young adults with mediastinal disease — identify the fibrosis pattern (collagen bands + lacunar cells) as the architectural hallmark. SDL3 provides the WHO classification framework.

Section 5 — Clinicopathological Correlation & Staging (SDL3, SDL4)

Integrate the history and histology: (a) What is the final diagnosis? (b) What Ann Arbor stage would you assign based on the information given, and why? (c) Name ONE cytokine released by RS cells that explains the B symptoms and ONE that explains the eosinophilia in the biopsy.

Guidance: Cervical + mediastinal involvement = both sides of the diaphragm? Clarify whether 'mediastinal' counts as a separate region. B symptoms (fever, night sweats, weight loss >10%) up-stage to 'B'. SDL4 discusses cytokine biology: IL-5 drives eosinophilia; IL-6/TNF-α drive constitutional symptoms. Assign Stage IIB or IIA depending on your reasoning — either is acceptable if justified.

Section 6 — Reflection: Pattern Recognition & Pitfalls (SDL1–SDL4)

Write a short reflection (100–150 words) addressing: (a) Which single feature at presentation most strongly steered you toward lymphoma over the other differentials? (b) Describe ONE situation where a young patient with identical B symptoms and cervical lymphadenopathy would turn out to have tuberculous lymphadenitis rather than HL — what histological finding would clinch that diagnosis? (c) What is the most important lesson this case teaches about lymph node biopsy technique?

Guidance: Synthesis questions reward integration across SDLs. Strong answers will contrast RS cells (SDL4) with epithelioid granulomas + Langhans giant cells (SDL2), highlight the shared B symptom profile that makes TB–HL distinction a classic clinical trap, and reinforce the excision-over-FNAC principle from Section 3.

PEER REVIEW

You will review one anonymised peer submission. Your peer review must: (1) Score each rubric criterion honestly using the 5-point scale provided — do not award full marks by default. (2) For Section 4, verify that the WHO subtype and IHC reasoning are correct against SDL4; if they are wrong, note the error specifically. (3) Identify ONE strength (a line of reasoning you found genuinely illuminating) and ONE area for improvement (a specific gap, not a style comment). (4) Write 80–120 words of constructive feedback in professional language — avoid phrases such as 'good job' or 'needs improvement' without explanation. Your peer review is graded: substantive, evidence-linked feedback earns full peer-review marks; vague or copied-sounding feedback earns zero.