A Curious Case of Biopsy-Proven Usual Interstitial Pneumonia

Usual interstitial pneumonia (UIP) refers to a combination of radiologic and histologic findings, which include patchy interstitial fibrosis with fibroblastic foci and dense acellular collagen that causes architectural distortion due to scarring and honeycomb change with alternating areas of normal lungs. The UIP pattern is not a synonymous term with idiopathic pulmonary fibrosis (IPF). IPF is diagnosed when an etiologic workup has been performed, deemed to be unrevealing, with a radiologic or histologic UIP pattern. While the 2018 American Thoracic Society (ATS)/European Respiratory Society (ERS) guideline categories of UIP help eliminate the need for surgical lung biopsy (SLB) in two categories, i.e., "definite UIP" and "probable UIP," when characterizing a patient in the other categories, clinicians should wary about prolonging SLB in patients to determine the fibrosis pattern. Changes in the treatment and overall prognosis of patients can occur due to SLB confirming a UIP pattern on histology. Here, we report the case of a patient with an indeterminate UIP pattern on high-resolution computed tomography (HRCT) with histopathologic diagnosis of UIP on SLB. With no underlying identifiable cause for the UIP pattern, the patient was diagnosed and managed as IPF, ultimately requiring lung transplantation. This case highlights the importance of pursuing surgical lung biopsy in patients with indeterminate UIP on HRCT scanning to facilitate prompt treatment and guide further management.