DIFFUSE IDIOPATHIC PULMONARY NEUROENDOCRINE HYPERPLASIA IN A PATIENT WITH MYCOBACTERIUM AVIUM COMPLEX

Abstract

TOPIC: Lung Cancer TYPE: Medical Student/Resident Case Reports INTRODUCTION: Diffuse idiopathic pulmonary neuroendocrine hyperplasia (DIPNECH) is a preneoplastic lesion that can progress to carcinoid tumors. It differs from reactive hyperplasia in its expression of tumor antigens such as Ki67 as well as the possibility of progression to carcinoid tumors. We present a case of an elderly female with a dry cough who was found to have a lung nodule showing granulomatous inflammation and a focus of neuroendocrine cell hyperplasia suggesting DIPNECH. CASE PRESENTATION: A 78-year-old female with a history of rheumatoid arthritis, breast cancer post excision and radiation therapy, presented with dry cough for a few months. She had a ten-pack-year history of smoking and quit eight years ago. She denied fevers, chills, night sweats, or acute weight changes. Chest CT and PET scan revealed a right middle lobe (RML) lung nodule with increased metabolic activity. EBUS and bronchoscopy specimens did not reveal any organisms or abnormal cytology. The patient underwent wedge resection of the RML. Pathology revealed extensive chronic inflammatory infiltrate with necrotizing granulomas and sparse foreign body giant cells, and a focus of bland appearing cells that stained positive for chromogranin and synaptophysin indicating neuroendocrine differentiation. MiB-1 proliferation index was 1%. Tissue culture grew MAC. A diagnosis of DIPNECH was established. On resection of the nodule, our patient's symptoms resolved, and she required no further therapy. On follow-up at 1.5 years, she was asymptomatic. DISCUSSION: DIPNECH is a rare lung condition presenting mainly with dry cough. CT chest can show solitary or bilateral pulmonary nodules, mosaic perfusion, bronchial wall thickening, ground-glass opacities, air trapping, or bronchiectasis. MiB-1 (antibody to Ki67) expressed in her case indicates tumor antigen expression supporting a diagnosis of DIPNECH vs. reactive hyperplasia. The miB-1 index was 1%, predicting low mitotic activity and a better prognosis. Tissue cultures of her resected specimen grew MAC. MAC is not known to be associated with such a preneoplastic condition. As per our literature review, only two other cases have been reported that describe the concurrence of pulmonary neuroendocrine growth and lung infection. MAC was associated in both these cases. Overall, most patients with DIPNECH experience a stable clinical course. However, severe clinical decline has been reported in a few. CONCLUSIONS: DIPNECH is a rare preneoplastic condition with a good prognosis, although it can sometimes progress to carcinoid tumors with clinical deterioration. Identification of risk factors may be helpful in timely diagnosis and treatment of DIPNECH. MAC is one such factor that seems to be associated with DIPNECH. Further studies should be undertaken to investigate their relationship. REFERENCE #1: Böhm J, Koch S, Gais P, Jütting U, Präuer HW, Höfler H. Prognostic value of MIB-1 in neuroendocrine tumours of the lung. J Pathol. 1996;178(4):402-409. doi:10.1002/(SICI)1096-9896(199604)178:4<402::AID-PATH498>3.0.CO;2-5 REFERENCE #2: Chassagnon G, Favelle O, Marchand-Adam S, De Muret A, Revel MP. DIPNECH: when to suggest this diagnosis on CT. Clin Radiol. 2015;70(3):317-325. doi:10.1016/j.crad.2014.10.012 REFERENCE #3: Krvavac A, Patel PH, Kamel G, Najmuddin M, Nayak RP, Patolia S. Pulmonary Neuroendocrine Cell Hyperplasia in a Patient with Mycobacterium avium Complex. Am J Respir Crit Care Med. 2018 Nov 1;198(9):e109-e110. doi: 10.1164/rccm.201801-0199IM. PMID: 30130431. DISCLOSURES: No relevant relationships by Lipisha Agarwal, source=Web Response No relevant relationships by Divyansh Bajaj, source=Web Response No relevant relationships by Chinmay Jani, source=Web Response No relevant relationships by Joseph Khoory, source=Web Response No relevant relationships by Abdullah Melhim, source=Web Response No relevant relationships by Gabriel Ryan, source=Web Response No relevant relationships by Harpreet Singh, source=Web Response