A 35-year-old smoker presents with dyspnea and a pneumothorax. HRCT shows bilateral upper lobe predominant thin-walled cysts and nodular lesions. Biopsy shows proliferation of Langerhans cells with grooved 'coffee-bean' nuclei. Which cell surface marker is most useful for confirming the diagnosis?
- A CD68
- B S-100 protein only (without CD1a)
- C CD1a ✓
- D CD20
Correct answer: C. CD1a
Explanation
Pulmonary Langerhans cell histiocytosis (PLCH) is characterized by proliferation of Langerhans cells that express both CD1a and langerin (CD207) and show Birbeck granules on electron microscopy. S-100 is positive but less specific. CD68 is a macrophage marker. CD20 is a C-cell marker. PLCH is strongly associated with cigarette smoking in young adults.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.