NON-RESOLVING PNEUMONIA: AN INDOLENT MALIGNANCY AND A CONGENITAL MALFORMATION; A TALE OF DELAYED DIAGNOSIS

Abstract

SESSION TITLE: Monday Fellow Case Report Posters SESSION TYPE: Fellow Case Report Posters PRESENTED ON: 10/21/2019 02:30 PM - 03:15 PM INTRODUCTION: Non-resolving pneumonias can occur due to infectious, noninfectious or neoplastic causes. We present a patient treated for recurrent pneumonia despite persistence on imaging for 6 years before being diagnosed with lung adenocarcinoma. CASE PRESENTATION: A 56 year old man, non-smoker, presented to our clinics for a second opinion regarding a persistent right lower lobe pneumonia. His symptoms began 6 years ago with 2 weeks of fever and productive cough. He had a WBC of 13.8 (neutrophil predominance) but negative blood cultures, ANA, ANCA, and fungal serologies. A chest CT showed a RLL 8 cm cystic lesion with air fluid level, scattered sub-centimeter pulmonary nodules, and mediastinal lymphadenopathy. BAL was lymphocyte predominant but no growth on bacterial, fungal, or mycobacterial cultures. The patient was discharged on amoxicillin clavulanic acid for 6 weeks with resolution of his symptoms but radiographic persistence of lesion. A CT guided biopsy performed 3 months later was negative for malignancy. The lesion was followed with CT chests annually for the next 5 years with no change. Nine months prior to presenting to our clinic the patient developed fevers and a cough. The CT chest showed a 8 cm mixed cavitary and solid lesion with ground glass in the RLL. He was treated with another course of antibiotics with resolution of symptoms. In our clinic, he underwent a PET-CT, which showed a SUVmax of 3.2 in the solid component of the lesion. Due to suspicion of a slow-growing malignancy, he underwent lobectomy, which showed a 7 cm mucinous adenocarcinoma. A record review discovered a CT scan 20 years prior with a large area of lucency in the RLL suggestive of congenital emphysema or a congenital pulmonary airway malformation (CPAM). DISCUSSION: The case illustrates the clinical entity of non-resolving pneumonia. Pneumonias visualized on chest x-ray can be expected to resolve by 6 weeks in healthy lungs. In fibrotic or obstructive lung disease the duration is up to 16 weeks (1). The patient’s clinical improvement but lack of radiographic improvement should raise alarm. The patient appropriately underwent further testing, however negative results on CT-guided biopsies have been shown to miss a malignant process in about 50% of cases(2). Malignancy is an uncommon cause of non-resolving pneumonia with an incidence of 1-2% (3). Underlying lung disease such as emphysema and CPAM can increase the risk of malignancy. CPAM is a rare disease occurring in 1:30,000 deliveries and is due to adenomatous hyperplasia of bronchiolar epithelium leading to cysts. The cysts are lower lobe predominant and tend to become infected. Current management for adults with CPAM is wedge resection. CONCLUSIONS: Patients with CPAMs can have a higher incidence of cancer. Non-resolving pneumonias should be followed closely and negative results on CT-guided biopsy are associated with a 50% false negative rate. Reference #1: Jay SJ et al. (1975) NEJM. Oct 16;293(16):798-801. Reference #2: Fontaine-Delaruelle C. et al. (2015) Chest., 148(2):472-480 Reference #3: Soysetha V et al. (2007). Lung Cancer. 57(2):152-8. Epub 2007 Apr 25 DISCLOSURES: No relevant relationships by Sumedh Hoskote, source=Web Response No relevant relationships by Cameron Long, source=Web Response