Lymphomatoid granulomatosis mimicking PJP infection

A male patient in his 40s who had been unwell for months with fever of unknown origin and clinicopathological features suspicious for haemophagocytic lymphohistiocytosis presented to hospital with worsening subacute shortness of breath. CT pulmonary angiogram demonstrated ground glass changes involving all lung lobes with an apicobasal gradient. These changes, combined with long-term steroid exposure for granulomatous hepatitis without pneumocystis prophylaxis, raised concern for pneumocystis jirovecii pneumonia (PJP). A subsequent bronchoscopic lavage specimen was positive on PCR for PJP and the patient was started on appropriate therapy. Clinical and radiological changes initially improved but after completion of therapy, symptoms and radiological abnormalities returned. Retreatment with second-line treatment resulted again in initial improvement followed by relapse with acute deterioration. Further investigations for an alternate diagnosis were made, with a surgical lung biopsy performed finally revealing immunosuppression-related Epstein-Barr virus positive large B cell lymphoma with lymphomatoid granulomatosis of grade 3 pattern.