Diffuse Idiopathic Neuroendocrine Cell Hyperplasia (DIPNECH) on Electromagnetic Navigation Bronchoscopy (EMN) Guided Fine Needle Aspiration (FNA): A Case Report

Introduction/Objective DIPNECH is a clinicopathological diagnosis characterized by abnormal proliferation of single or clusters of neuroendocrine cells in the bronchial mucosa. The World health organization includes DIPNECH as a preinvasive lesion to carcinoid tumors of the lung. Diagnosis is often delayed or missed due to insidious presentation and rarity of the disease. High degree of suspicion in the appropriate clinical and radiological context is important for early diagnosis. We describe a unique case of DIPNECH diagnosed by EMN guided aspiration cytology in the setting of multiple incidental lung nodules and confirmed on surgical resection. Methods/Case Report A 69-year-old female with history of insidious cough was referred to pulmonology clinic for multiple incidental bilateral lung nodules detected by CT scan, largest involving the right middle lobe. Although the main diagnostic consideration was pulmonary metastasis, several radiological features, including diffuse mosaic attenuation pattern, prompted the possibility of a diffuse neuroendocrine process. Electromagnetic navigation bronchoscopy (ENB) guided fine needle aspiration cytology was performed. Air-dried and Papanicolaou stained smears were scant but showed dispersed and clusters of small cells with fine chromatin with minimal cytoplasm. No necrosis or mitosis were seen. A cell block was prepared that showed rare clusters of tumor cells positive for immunostains synaptophysin, chromogranin, CD56, with a Ki-67 of 1%. In the appropriate clinical and radiological context findings were consistent with a well differentiated neuroendocrine process such as DIPNECH. Right middle lobe resection confirmed extensive DIPNECH with multiple typical carcinoid tumors and tumorlets. Results (if a Case Study enter NA) NA Conclusion It is essential to be familiar with the clinical and radiological findings of DIPNECH and include it in the differential diagnosis of its mimickers. Although the diagnosis is challenging on limited specimens, this report indicates that EMN guided aspiration cytology can be used as a valuable early tool for accurate diagnosis and timely management of DIPNECH.