Diffuse Idiopathic Pulmonary Neuroendocrine Cell Hyperplasia (DIPNECH) Complicated by Endobronchial Mycobacterium abscessus Infection and Tracheomediastinal Fistula

Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) is a rare pulmonary disorder that can mimic other more common lung diseases, leading to delays in diagnoses. We present a patient with biopsy-confirmed DIPNECH following years of nonspecific symptoms and innumerable pulmonary nodules on imaging. Their clinical course rapidly declined after being diagnosed with Mycobacterium abscessus pulmonary disease complicated by a tracheomediastinal fistula and an endobronchial lesion, co-existing diagnoses not previously described in the literature. We discuss the diagnostic challenges posed by overlapping clinical and radiographic features of DIPNECH and nontuberculous mycobacterial pulmonary disease, highlight potential risks of prolonged corticosteroid exposure, and emphasize the need for heightened clinical suspicion in patients with atypical disease progression.