Case ReportDiffuse idiopathic pulmonary neuroendocrine cell hyperplasia
Introduction
Pulmonary neuroendocrine cell (PNEC) hyperplasia has been conventionally considered as a reactive process associated with regeneration of chronically injured airways or alveoli, such as in lung abscess, bronchiectasis, cystic fibrosis, and chronic obstructive pulmonary disease. In 1992, Aguayo et al [1] described 6 nonsmoking patients who presented with diffuse PNEC hyperplasia without any known pulmonary diseases. The authors postulated that these patients might belong to a distinct new entity of diffuse hyperplasia of PNEC without primary causes. After the initial report, more than 30 additional cases have been described [2], [3], [4], [5], [6], [7], [8], and the term diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) became widely accepted for this new entity. The World Health Organization recognized this condition in the 1999 classification [9] and considered it as a preinvasive lesion of pulmonary carcinoid tumor. We describe a patient who was treated for bronchial asthma for 5 years before he was diagnosed as DIPNECH by open lung biopsy. The previous reported cases of DIPNECH were analyzed along with the current case for the common features in clinical presentation, radiologic imaging, pulmonary function testing, and pathologic examination.
Section snippets
Report of a case
The patient is a 41-year-old white man with a 5-year history of insidious onset of exertional dyspnea, cough, and wheezing. He denied history of any chronic pulmonary disorders or major systemic diseases. He worked as a medical technician in an emergency department. For the last 15 years, he has not smoked, but he did have a history of smoking for 6 years (0.5 pack per day). He was initially diagnosed with bronchial asthma and received treatment for the past 2 years with bronchodilators and
Pathologic findings
The open lung biopsy yielded 2 fragments of pink-tan, soft lung tissue without nodules or remarkable gross lesions. A distinct histologic feature was diffuse proliferation of bland cells involving the bronchiolar epithelium (Fig. 2). Cytologically, these cells have typical neuroendocrine features, including uniform oval-to-round nuclei, fine-stippled chromatin granules, inconspicuous nucleoli, and a moderate amount of eosinophilic cytoplasm. The cells formed clusters in the epithelium,
Discussion
DIPNECH is an exceedingly rare lung lesion characterized by generalized proliferation of PNEC often confined to the epithelium of bronchioles. Careful review of the literature disclosed 39 cases [1], [2], [3], [4], [5], [6], [7], [8]; they are analyzed with the current case and are summarized in Table 1. Although the age distribution appeared relatively wide (22-79 years), most patients presented in their fifth or sixth decades (mean age, 58 years). Females distinctly predominated, with a male
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2015, Clinical RadiologyCitation Excerpt :Pulmonary function test alteration is reported to be moderate to severe in 44% of cases.10 It has been suggested that normal pulmonary function tests may represent the early phase of the disease when the airway obstruction is not severe enough to be detected.16 DIPNECH is defined as a proliferation of pulmonary neuroendocrine cells that do not cross the basement membrane.7