A Rare Case of Acute Interstitial Pneumonia Diagnosed at Autopsy. (28th October 2020) - Conner, E
Abstract: Introduction/Objective: Acute interstitial pneumonia (AIP) is a rare disease clinically characterized by rapidly progressing respiratory failure in individuals with no history of respiratory illness or other inciting factors. While most often diagnosed in middle-aged adults, it may present in any age group. Initial presentation is described as influenza- like, and respiratory failure requiring ventilatory support often progresses within weeks to months. Prognosis is poor, with an estimated mortality rate approaching 80% without treatment. Methods: We present the case of a 44-year-old male nonsmoker with no significant medical history, who presented in 2018 with 1.5 months of dyspnea and headache initially diagnosed as atypical pneumonia. Chest imaging revealed bilateral opacities; however, microbial workup revealed no evidence of infectious etiology. Autoimmune serology studies were likewise unrevealing. Despite aggressive supportive and medical management, he deteriorated to respiratory failure and succumbed. Results: At autopsy, the lungs were symmetrically congested and edematous (combined weight 2, 340 g) but free of evident consolidation or discrete lesions. Microscopic examination revealed diffuse alveolar damage with extensive hyaline membrane formation, interstitial edema, and fibroblastic proliferation. The vasculature was severely congested, and the alveoli contained hemorrhage and scattered macrophages. No fungal or mycobacterial elements were identified by staining. Based on the histologic features and clinical context, the diagnosis of AIP was made. Conclusion: AIP is a rare, aggressive, and diagnostically challenging disease that includes a broad range of both clinical and histologic differentials. Timely recognition and intervention with aggressive respiratory support and high- dose glucocorticoids are the mainstays of clinical management. The diagnostic role of histology is significant, but hinges on early clinical consideration of AIP as disease progression may later preclude the biopsy procedure. We share this case to raise awareness of this rapidly progressive and diagnostically troubling interstitial lung disease while emphasizing the importance of clinicopathologic correlation.