Abstract Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) is a rare pre-invasive carcinoid tumor characterized by abnormal pulmonary neuroendocrine (NE) cell proliferation. DIPNECH primarily affects older women and presents with chronic cough. The classic radiologic finding of diffuse non-calcified nodules with mosaic attenuation is non-specific and therefore requires histopathologic confirmation. We present a unique case of DIPNECH with prominent findings of lung cysts diagnosed initially with cryobiopsy and confirmed by surgical lung biopsy. This case provides further support for cryobiopsy in the evaluation of cystic lung disease and for the diagnosis of DIPNECH. A 36-year-old female with history of pituitary adenoma controlled on cabergoline was referred to pulmonary clinic for 10-year history of refractory cough and dyspnea diagnosed as asthma. History was pertinent for minimal smoking in her teenage years, secondhand smoke exposure in childhood, and family history of SLE in her father. Potential contributors including GERD and upper airway disease were evaluated and ruled out, and patient had only mild improvement with step-up regimen ICS/LABA. Pulmonary function test revealed mild airway obstruction with positive bronchodilator response, but unexplained severely reduced DLCO. Hence, a CT chest (Figure1A) was obtained showing bilateral diffuse thin-wall cysts and several micronodules. Given age and history, there was high suspicion of Lymphangiomyomatosis (LAM). Autoimmune panel, VEGF-D levels, CT abdomen/pelvis for other visceral organ involvement were unremarkable and histopathologic diagnosis was pursued. Cryobiopsy (Figure 1B) was performed due to increasing support in the literature for LAM diagnosis, revealing RLL carcinoid tumorlets positive for synaptophysin and chromogranin, demonstrating NE differentiation. Cytology and smooth muscle stains— actin, HMB-45, and Melan-A were negative excluding LAM. Per ILD Conference discussion, carcinoid tumorlets were thought to be an incidental finding with potentially inadequate sampling for cystic lung disease. Therefore, she was referred to thoracic surgery. She underwent right lung thoracoscopy with biopsy again revealing carcinoid tumorlets/ NE hyperplasia confirming the diagnosis of DIPNECH. Patient is now referred to Cleveland Clinic for second opinion given atypical presentation of DIPNECH. DIPNECH is an indolent NE disease with difficult-to-control obstructive symptoms and varied phenotypic penetrance, typically with nodules and mosaic attenuation and rarely with lung cysts. This case not only demonstrates an atypical presentation of DIPNECH but also demonstrates that cryobiopsy is a valid alternative to surgical lung biopsy for tissue diagnosis of DIPNECH. Histopathologic confirmation of DIPNECH by cryobiopsy is not well established but gaining increasing support through case reports. This abstract is funded by: None
Patel et al. (Fri,) studied this question.