P2.16: Atypical Adenomatous Hyperplasia (AAH) in a Patient With a Primary Carcinoid Lung Tumor: Case-Report

Abstract

AAH is considered a premonitory lesion in the pathological pathway leading to adenocarcinoma (AC). However, previous studies have suggested a less common but existing association between AAH and other types of primary lung cancer, including carcinoid tumors (CT). We describe the case of a patient with an incidental diagnosis of typical CT in whom was found an AAH concomitantly. Review of medical history, imaging studies and pathology. 59-year-old woman with history of diverticular disease visited the hospital in Sep/2015 with abdominal pain. Not abnormal findings on physical examination, but lung nodules were incidentally observed in abdominal CAT. Chest CAT reported three nodular lesions: right inferior lobe (4mm), medial segment (6 mm), lateral segment (9mm) spiculated with pleural tail and left adrenal gland (11mm). The patient refers weight loss (6kg) but denies respiratory symptoms. Chest surgery performs lung resection by thoracoscopy, obtaining a 12mm nodule with retraction of visceral pleura in the right inferior lobe. Pathology reports a typical CT, KI67 4%, low-grade neuroendocrine tumor, well differentiated, grade 1. A right inferior lobectomy was done by thoracoscopy with mediastinal lymphadenectomy. Pathology described the morphological pattern and immunophenotypical profile of an AAH. No residual CT was found. AAH has been described as a putative lesion preceding lung AC (OR 2.97; 95% CI 1.82-4.85). However, previous case-series of patients with resected lung for primary lung carcinoma found AAH in other primary lung tumor subtypes, including 3.3% patients with lung CT2. To our knowledge, this is the first case described of a typical CT with a concomitant finding of AAH. Further studies are required in larger samples to confirm this finding. Despite the strong association between AAH and AC, it must be considered as a histopathological finding in the context of other primary lung neoplasms, such as the typical CT.