40 year old male RV positive , reports with progressively worsening dyspnoea, hpoxemia on room air .

Describe the radiological findings, differential diagnosis and next investigations.

Bilateral ,diffuse, reticulonodular infiltrates with perihilar distribution, most likely PCP , other differentials -koch's,LIP, CMV etc .LDH may be raised,Sputum/BAL likely to show PC on SM stain.If inconclusive Tranbronchial lung biopsy may be needed.