A PICTURE IS NOT ALWAYS WORTH 1,000 WORDS: A CASE OF DIP MASQUERADING AS UIP

Abstract

SESSION TITLE: Medical Student/Resident Diffuse Lung Disease SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: October 18-21, 2020 INTRODUCTION: Desquamative Interstitial Pneumonia (DIP) is a rare idiopathic interstitial pneumonia which has findings of pigmented macrophages and giant cells on histopathology and is often associated with smoking tobacco. Radiographically, DIP is commonly described as widespread patchy ground glass opacities with a predilection for lower lung zones.[1] Here we present a unique case of DIP which initially presented as probable interstitial pulmonary fibrosis with usual interstitial pneumonia (UIP) pattern on CT imaging in a former smoker. CASE PRESENTATION: The patient is a 68-year-old Vietnamese male with no known past medical history who initially presented with 3 months of worsening dyspnea and dry cough associated with 5lbs weight loss. He immigrated to the United States ten years ago and had been treated for latent tuberculosis at that time. He was a 20 pack year smoker but had quit ten years prior to presentation. He works in a nail salon with exposures to polish and chemicals, but otherwise denied other occupational exposures. He has no pets and has been living in the same home for more than five years. On initial presentation the patient was found to be hypoxic with resting oxygen saturation of 86%. High resolution CT (HRCT) had findings consistent with fibrosing interstitial lung disease in a probable UIP pattern with some small areas of ground glass opacities in bibasilar lung fields (Image A & B). PFTs were performed which showed a TLC of 62% of predicted consistent with severe restriction. Rheumatic panel was unremarkable aside from a mildly elevated CRP at 2.0 mg/dL. He underwent surgical lung biopsy which confirmed a diagnosis of DIP. He was started on prednisone 60mg daily with improvement in his PFTs and clearance of ground glass opacities on imaging (Images C & D) at 1-month follow up. He experienced undesirable side effects due to prednisone. Therefore, mycophenolate mofetil 500mg twice daily was started and his prednisone was reduced to 40mg daily. At 3-month follow-up he continued to have symptomatic improvement and has been weaned off supplemental oxygen. DISCUSSION: DIP is a rare idiopathic interstitial pneumonia with radiographic findings of bilateral patchy ground glass opacification in a mid to lower lung zone distribution. Infrequently limited honeycombing or traction bronchiectasis can be seen.[2] DIP was very low on the initial differential diagnosis for this patient with initial CT imaging consistent with probable UIP. Surprisingly, surgical biopsy confirmed findings of DIP and the patient has done remarkably well after starting immunosuppressive therapy. CONCLUSIONS: This case demonstrates that there can be a large discrepancy between what imaging suggests and what biopsy confirms. This example further supports the ATS guidelines on obtaining a surgical biopsy for probable radiographic UIP as it can have major ramifications in terms of treatment strategy.[3] Reference #1: Godbert B, Wissler MP, Vignaud JM. Desquamative interstitial pneumonia: an analytic review with an emphasis on aetiology. Eur Respir Rev. 2013;22(128):117-123. doi:10.1183/09059180.00005812 Reference #2: Wells AU, Hirani N. Interstitial lung disease guidelines: the British Thoracic Society in collaboration with the Thoracic Society of Australia and New Zealand and the Irish Thoracic Society. Thorax 2008; 63: Suppl. 5, v1–v58 Reference #3: Raghu G, Remy-Jardin M, Myers JL, et al. Diagnosis of Idiopathic Pulmonary Fibrosis. An Official ATS/ERS/JRS/ALAT Clinical Practice Guideline. Am J Respir Crit Care Med. 2018;198(5):e44-e68. doi:10.1164/rccm.201807-1255ST DISCLOSURES: No relevant relationships by Michael Morris, source=Web Response No relevant relationships by Taj Rahman, source=Web Response