A 28-year-old man presents with recurrent pneumothorax (3rd episode in 2 years) and progressive dyspnea. CXR and CT chest show bilateral basilar cystic changes with diffuse nodular infiltrates. He is a non-smoker. Serum VEGF-D level is 1980 pg/mL (normal <800 pg/mL). The diagnosis is:
- A Pulmonary Langerhans cell histiocytosis (PLCH)
- B Birt-Hogg-Dubé syndrome
- C Emphysema
- D Lymphangioleiomyomatosis (LAM) ✓
Explanation
Lymphangioleiomyomatosis (LAM) presents in women of childbearing age with progressive dyspnea, recurrent pneumothorax, and chylothorax. HRCT shows diffuse bilateral thin-walled pulmonary cysts. Serum VEGF-D >800 pg/mL is highly specific for LAM (sensitivity 69%, specificity 100% per ERS guidelines), allowing diagnosis without biopsy when combined with compatible HRCT. Pulmonary LCH in young smokers shows centrilobular nodules with upper-lobe cysts; VEGF-D is not elevated. Birt-Hogg-Dubé causes renal tumors, fibrofolliculomas, and lung cysts but VEGF-D is not elevated.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.