A 65-year-old male smoker develops hemoptysis and a right hilar mass. Biopsy shows pleomorphic cells with intercellular bridges (desmosomes), pink cytoplasm, and keratin pearls. Which IHC profile confirms the diagnosis?
- A TTF-1+, CK7+, napsin A+
- B CK5/6+, p40+, p63+ ✓
- C Synaptophysin+, chromogranin+, CD56+
- D CD45+, LCA+, CD20+
Correct answer: B. CK5/6+, p40+, p63+
Explanation
Squamous cell carcinoma of the lung is confirmed by squamous markers CK5/6, p40, and p63. Keratin pearls and intercellular bridges are classic histological features. TTF-1 and napsin A are markers of pulmonary adenocarcinoma. Synaptophysin, chromogranin, and CD56 are neuroendocrine markers (small cell/carcinoid). CD45 and CD20 identify lymphomas.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.