A Case of Acute Interstitial Pneumonia (AIP)

Abstract

Introduction: Acute interstitial pneumonia (AIP) also known as Hamman-Rich Syndrome is an uncommon, acute, and rapidly progressive idiopathic pulmonary disease that often leads to acute respiratory distress syndrome (ARDS). We present a case of a 52-year-old male who developed this condition. Case: A 52-year-old male with no past medical history presented to the emergency department with a 3-day history of progressively worsening dyspnea, dry cough, and chills. Prior to symptom onset, he was in his usual state of health but did report having polyarthralgia mainly involving large joints with no other associated symptoms. He denied a history of sick contacts including COVID exposure, sexually transmitted infections, incarceration, intravenous drug abuse, or travel to tuberculosis endemic countries. He denied tobacco use and any other form of illicit drug use. On physical examination, he was afebrile, tachycardic, and hypoxic on room air. He appeared to be in no respiratory distress and chest was clear to auscultation. There were no joint abnormalities, skin rashes, or lymphadenopathy. Lab workup revealed elevated D-Dimer (2140 ng/mL), CRP (50 mg/L), lactate dehydrogenase (296 IU/L), ferritin (578 ng/mL). His SARSCoV2 PCR was negative. Chest X-ray and CT chest both revealed right pleural effusion and diffuse reticular and ground-glass opacities. He underwent thoracentesis and fluid analysis revealed lymphocytic exudate with negative cultures. Antibiotics and steroids were initiated. He underwent a complete rheumatologic workup including myositis panel, due to concern for possible autoimmune etiologies and it was negative. His respiratory status worsened, and he eventually required intubation. At this point given unclear etiology, he underwent bronchoscopy with transbronchial cryobiopsy. Cryobiopsy revealed evidence of organizing phase of diffuse alveolar damage (Figure 1) and in the setting of negative cultures, COVID-19 and autoimmune panel, there was a growing concern for acute interstitial pneumonia. The patient was started on pulse dose of steroids and transferred to a transplant center for lung transplantation evaluation. Discussion: Acute interstitial pneumonia is a rare idiopathic clinicopathological condition that is characterized clinically by rapid onset of respiratory failure in patients with no past medical history of pre-existing lung disease. Histopathological findings are identical to those of diffuse alveolar damage. Closely resembling ARDS, it is frequently confused with other clinical entities characterized by rapidly progressive interstitial pneumonia. Considering this a high index of suspicion is required to diagnose these patients and institute appropriate management as mortality is as high as 70%. (Figure Presented).