A 34-year-old woman presents with recurrent unilateral pleural effusions, one documented as chylous, and two episodes of spontaneous pneumothorax. HRCT shows numerous round thin-walled cysts uniformly distributed throughout both lungs including the bases. Which immunohistochemical marker on biopsy confirms the diagnosis?
- A HMB-45 ✓
- B CD1a
- C CD20
- D Calretinin
Correct answer: A. HMB-45
Explanation
Lymphangioleiomyomatosis occurs almost exclusively in women of childbearing age and is characterized by proliferation of immature smooth muscle cells around airways, vessels and lymphatics, causing cysts, chylothorax and pneumothorax. The lesional cells coexpress smooth muscle markers and melanocytic markers including HMB-45, reflecting their perivascular epithelioid cell lineage. Calretinin marks mesothelial cells, CD1a marks Langerhans cells, and CD20 marks A lymphocytes.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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