Pseudotumor or pseudomonas?

SESSION TITLE: Unusual Chest Infections 1 SESSION TYPE: Rapid Fire Case Reports PRESENTED ON: 10/09/2023 09:40 am - 10:25 am INTRODUCTION: Empyema necessitans (EN) is a rare, but often deadly complication of empyema that occurs when infection spreads outside the pleural space and invades the chest wall. The disease demands prompt diagnosis and treatment to avoid significant morbidity. We describe a patient with a chest wall mass and an associated pleural effusion, who was ultimately diagnosed as EN due to Pseudomonas Aeruginosa (PA). CASE PRESENTATION: An 82-year-old male veteran with bronchiectasis and chronic hypoxia on 2 liters nasal cannula presented with a one month history of fevers, chills and a 30-pound unintentional weight loss. Family members also noted a large left sided chest mass, for which a computed tomography (CT) of the chest revealed a large left-sided pleural-based mass with an adjacent fluid collection extending into the soft tissue overlying the chest wall. The mass was easily palpable on the physical exam and noted to have interior heterogeneity on Point of Care Ultrasound (POCUS). A left sided chest tube was placed for aspiration and drainage, and fluid cultures grew pan susceptible PA. Sputum testing obtained on admission grew the same PA species. After adequate drainage of the empyema and a 28-day course of Levofloxacin, the patient was discharged following chest tube removal. On follow up, CT imaging showed complete resolution of the EN. DISCUSSION: EN is a rare complication of an untreated parapneumonic effusion in which the resulting empyema spreads outside the pleural space and invades the surrounding soft tissue of the chest wall. The causative organism will often be the same infection that precipitated the pneumonia. 75% of documented cases revealed infection with M. Tuberculosis and Actinomyces spp. as the underlying etiology (1). Although 17% of community-acquired empyema infections are believed to be caused by gram negative organisms, there are few documented cases of EN secondary to PA in immunocompetent adults (2). Diagnosis is often made radiographically, with POCUS being a well-established modality for the evaluation of superficial masses and pleural disease. While CT is the most sensitive for identifying focal pleural or chest wall abnormalities, differentiating an EN from an underlying malignancy can often remain a diagnostic challenge. Early identification and treatment of EN will prevent further progression and long-term sequelae, with antimicrobial therapy and source control via complete evacuation of the infectious cavity being the mainstay of treatment. CONCLUSIONS: We present a case of an 82-year-old veteran presenting with a chest wall mass subsequently diagnosed as Empyema Necessitans due to Pseudomonas Aeruginosa infection. We aim to highlight that the diagnosis of EN should be on the differential for any patient presenting with a new thoracic mass, regardless of documented infection. REFERENCE #1: White-Dzuro, C.G., Assi, P.E., Thomas, H.C. et al. Unusual presentation of empyema necessitans: case report and review of the literature. Gen Thorac Cardiovasc Surg 69, 1026–1030 (2021). https://doi.org/10.1007/s11748-021-01601-9 REFERENCE #2: Addala DN, Bedawi EO, Rahman NM. Parapneumonic effusion and empyema. Clin Chest Med 2021; 42: 637–647. DISCLOSURES: No relevant relationships by Jenna Dumovich No relevant relationships by Nicholas Hodgeman No relevant relationships by Kourtney King No relevant relationships by Nilam Soni No relevant relationships by Meilinh Thi