CASE PRESENTATION: A 19 year-old Caucasian female presented to the emergency room with complaints of chest tightness for one month. Exam revealed dullness to percussion and diminished breath sounds over the posterior left back. There was no palpable lymphadenopathy. A CXR showed a left pleural effusion. A CT of the chest, abdomen and pelvic was obtained revealing mediastinal lymphadenopathy, a large pleural effusion and enhancing left paraspinal soft tissue along the pleural surface. Thoracentesis obtained 1100mL of lymphocytic predominant transudative fluid. She returned 2 weeks later with shortness of breath and a CXR revealed a large left pleural effusion. CRP and ESR were 235 mg/L and 55 mm/hr respectively. Other lab data obtained: HIV, ANA, ANCA, Anti-Sm, Anti-DNA, fungal serologies, toxoplasmosis, bartonella, EBV PCR returned negative. Pleuroscopy revealed 1700 mL of serous fluid and inflamed parietal pleura which was biopsied. FNA was obtained using the EBUS with a 21G needle from stations 4R, 7, and 10R and then a 22G esophageal needle for 2 core biopsies from station 7. Pathology from all sites revealed histiocytes and acute necrotizing lymphangitis. All cultures and cytology were negative. Steroids were started with symptomatic improvement within 48 hours and decreased CRP and ESR to 178 mg/L and 19 mm/hr.