Alaws, Hossny

Abstract Introduction: Acute Eosinophilic pneumonia (AEP) is an eosinophilic pulmonary condition defined by symptoms of less than or equal to 1 month's duration, pulmonary infiltrates on imaging, pulmonary eosinophilia of 25% or greater on bronchoalveolar lavage (BAL) cell count or eosinophilic pneumonia on lung biopsy, and absence of other eosinophilic pulmonary diseases. It can be associated with a multitude of exposures, including medications, inhalants as well as systemic conditions. We report a case of AEP associated with intramuscular (IM) progesterone administration. Case: A 36-year-old female presented to the emergency department with dyspnea on exertion, cough productive of yellow sputum, and subjective fever of two days’ duration. She had undergone in vitro fertilization using IM Progesterone as luteal phase support and experienced a miscarriage one week prior. She had a heart rate of 132 and required oxygen at 2 Liters per minute via nasal cannula to maintain her saturation at 92%. Her complete blood count showed an absolute eosinophil count of 1800 cells/uL. She underwent a computed tomography angiography scan of the chest, which was negative for a pulmonary embolism but showed diffuse bilateral peripheral ground-glass opacities as well as consolidations in both lung bases. She was empirically started on prednisone 40 mg per day. She later underwent a flexible bronchoscopy with BAL of the right middle lobe as well as transbronchial cryobiopsies of the right lung. The BAL cell differential showed 63% eosinophils confirming the diagnosis of AEP. Pathology revealed patchy organizing pneumonia with scattered eosinophils. Autoimmune workup was negative, including antineutrophil antibodies, Anti-myeloperoxidase, and anti-proteinase-3 antibodies. Infectious workup, including blood, sputum, and BAL cultures, was also negative. The patient dramatically improved with steroid administration. Her symptoms resolved, and she was discharged on room air with a 4-week prednisone taper. A follow-up chest x-ray revealed resolution of the infiltrates. Discussion: AEP is a rare condition. One epidemiological study estimated the incidence of AEP at 9.1/100,000 person-years in a population of United States military personnel. Given the lack of other inciting medications and negative autoimmune and infectious workup, IM progesterone administration was deemed the likely etiology of her presentation. There are four case reports of IM progesterone as a cause of AEP. This case represents a classic presentation of AEP with the secondary to progesterone administration and with symptoms resolving promptly with steroid administration.

Abstract Rationale: Lymphoid Interstitial Pneumonia (LIP) is a rare interstitial lung disease characterized as a benign lymphoproliferative pulmonary condition. It is often associated with autoimmune conditions such as Sjögren's syndrome, immune dysregulatory syndromes, and common variable immunodeficiency. The incidence and prevalence of LIP remain unclear. While fluorodeoxyglucose (FDG) Positron Emission Tomography (PET/CT) findings have been documented for various diffuse parenchymal lung diseases, data specific to LIP is limited. This study aims to assess the utility of PET/CT in the evaluation of malignancy in patients with LIP, in addition to describing PET/CT findings in patients with known LIP who underwent PET/CT for any reason. Methods: This retrospective study involved a reviewof electronic medical records within the Mayo Clinic Enterprise to identify patients with an established diagnosis of LIP who had undergone PET/CT. Using ICD code J84.2, we identified patients with a diagnosis of LIP, and further selected for those who had undergone PET/CT between 2009 and 2023. We analyzed descriptive statistics, including the mean and prevalence of common PET/CT findings. Results: We identified 10 patients, all of whom had anestablished expert diagnosis of LIP and had undergone PET/CT for any reason. The mean age was 66 years, and all patients were female. Six of the ten patients (60%) underwent a lung biopsy, and six (60%) exhibited FDG uptake in the lungs, with maximum standard uptake value (SUVmax) uptake ranging from 2.0 to 8.2. Six of the imaging studies (60%) showed abnormal FDG uptake in one or more lymph nodes, with SUV maximum ranging from 2.4 to 7.8, and four (40%) demonstrated extrapulmonary FDG uptake. Four patients were diagnosed with a malignancy, the majority being MALT, with one being lung squamous cell carcinoma (SCC). Conclusion: Given the rarity of LIP, there is limiteddata on the utility and findings of PET/CT in these patients. Our study reveals that in patients with LIP, despite abnormal parenchyma in the background of inflammatory disease, malignancy was still likely in abnormally hypermetabolic regions. In this study, lymphoma was the most common malignancy isolated in patients with LIP. Nonetheless, malignancy other than lymphoma can occur, namely squamous cell carcinoma (SCC), and PET positivity can occur in LIP patients even in the absence of tissue proven malignancy. In patients with LIP, SUVmax does not appear to be a differentiating factor between those later diagnosed with lymphoma (SUVmax 2.0-8.2) and SCC (SUVmax=3.1).