PA7.1,PA22.1-5 | Diagnostic Cytology & Clinical Pathology — Case Study

CLINICAL SCENARIO

A 38-year-old woman presents with 10-day progressive jaundice, pale stools, dark urine, and right-upper-quadrant discomfort. Her primary-care physician has ordered a liver function panel, urine dipstick with microscopy, and a complete blood count. An abdominal ultrasound reveals a 2.8 cm hypoechoic mass at the head of the pancreas; a subsequent FNAC of the mass is sent to the laboratory. Your task is to interpret each panel systematically, localise the jaundice mechanistically, integrate the cytology report, and reason to a clinically defensible diagnosis.

Section 1 — LFT Pattern Recognition (PA22.1, PA22.2)

The following liver function results are available:

Classify the LFT pattern as hepatocellular, cholestatic, or mixed. Justify your classification using the AST/ALT to ALP ratio and the individual enzyme elevations. Comment on synthetic function.

Guidance: Focus on the enzyme ratio (transaminases vs. ALP/GGT). A ratio <1.5 (ALP/ALT dominant) favours cholestasis. Normal albumin + INR = preserved synthetic function. Expect ~150 words.

Section 2 — Bilirubin Fractions & Jaundice Localisation (PA22.2, PA22.3)

Given the bilirubin fractions (direct 8.6 / total 9.8 mg/dL, i.e. ~88% conjugated), and the urinalysis:

Using the bilirubin-metabolism pathway, localise the jaundice to prehepatic, hepatic, or posthepatic. Explain why conjugated bilirubin appears in urine, why urobilinogen is absent, and what the pale stools indicate mechanistically.

Guidance: Key logic chain: conjugated bilirubin is water-soluble → renal excretion; absent urobilinogen + pale stools = bile duct obstruction blocking intestinal bilirubin → no stercobilin/urobilinogen. Expect ~200 words.

Section 3 — Differential Diagnosis & Ranking (PA7.1, PA22.3)

Based on Sections 1 and 2, generate a ranked differential diagnosis for posthepatic (obstructive) jaundice in this patient. For each condition, state the single most discriminating feature that makes it more or less likely in this case (age, gender, mass on ultrasound, duration, constitutional symptoms). Include at least four differentials spanning benign and malignant causes.

Guidance: Expected differentials: carcinoma head of pancreas (most likely given mass + age + progressive course), choledocholithiasis, cholangiocarcinoma, ampullary carcinoma, primary sclerosing cholangitis (less likely). Students should rank by pre-test probability. Expect ~200 words.

Section 4 — FNAC Interpretation (PA7.1, PA22.4)

The cytopathology report reads:

"Smears show cellular aspirate with clusters and single malignant epithelial cells arranged in acinar/ductal patterns. Cells exhibit nuclear enlargement with irregular nuclear membranes, prominent nucleoli (1–2 per cell), coarse chromatin, and moderate pale cytoplasm. Background shows necrotic debris and inflammatory cells. Mucinous material is present intracellularly. No normal acinar tissue seen."

Morphology classification: Adenocarcinoma, consistent with pancreatic ductal origin.

(a) Identify and define five cytological features of malignancy visible in this report. (b) Explain the diagnostic utility of FNAC vs. core-needle biopsy for a pancreatic head mass. (c) State one key limitation of FNAC in this context.

Guidance: Malignant features: nuclear enlargement, irregular nuclear membrane, prominent nucleoli, coarse chromatin, necrosis. FNAC advantage = less invasive, rapid; limitation = sampling error, no architectural assessment (histology needed to grade). Expect ~220 words.

Section 5 — Integrated Diagnosis & Pathophysiology (PA22.1–22.5)

Synthesise all evidence (LFT pattern, bilirubin localisation, clinical features, FNAC) into a final integrated diagnosis. Then explain the pathophysiological mechanism by which a mass at the head of the pancreas produces obstructive jaundice — trace the sequence from ductal obstruction to conjugated hyperbilirubinaemia, pale stools, dark urine, and pruritus. Use a numbered mechanistic chain (minimum 6 steps).

Guidance: Expected chain: mass → CBD compression → bile back-pressure → failure of bile entry into duodenum → (i) no bilirubin to intestine → pale stools + absent urobilinogen; (ii) conjugated bilirubin refluxes into blood → hyperbilirubinaemia → renal excretion → dark urine; (iii) retained bile salts → pruritus. Expect ~230 words.

Section 6 — Clinical Pathology Communication & Reflection (PA22.5)

You are the pathology registrar. Write a concise structured report (4–6 bullet points, ≤120 words) summarising the key laboratory findings, the localised diagnosis, and the FNAC result for the treating surgeon's handover. Then, in 2–3 sentences, reflect: what one aspect of this case most challenged your reasoning, and what would you look for differently on a similar next case?

Guidance: Report should cover: cholestatic LFT pattern, conjugated hyperbilirubinaemia, obstructive localisation, FNAC adenocarcinoma. Reflection is personal and ungraded but required for peer-review exercise. Expect ~180 words.

PEER REVIEW

You will be assigned one anonymous peer submission to review. Use the rubric provided to score each of the five criteria independently. For each criterion:
1. State the score you are awarding (0–full marks).
2. Write 2–3 sentences justifying your score with reference to specific statements in the peer's work.
3. Identify one strength and one specific suggestion for improvement.

Your review must be constructive, evidence-based, and respectful. Reviews that simply state 'good work' or award full marks without justification will not receive credit. Minimum review length: 250 words.