History and clinical findings: A 67-year-old woman with a history of chronic obstructive pulmonary disease and breast cancer developed an increase in size and number of pulmonary nodules that had previously been stable over the course of 9 years.
Investigations: Thoracic computed tomography revealed a well-defined pulmonary lesion with a diameter of 1,1 × 1,1 cm, accompanied by multiple bilateral pulmonary nodules with a maximum size of 5 mm. Thoracoscopic resection of the major nodule was extended to a completive resection of an adjacent lung area that operatively showed a macroscopically noticeable hypervascularity. Histopathological examination assigned the larger lesion to a typical carcinoid; the additionally resected hypervascular lung parenchyma confirmed an accumulation of hyperplastic neuroendocrine cells in terms of a diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH).
Treatment and course: Since histological examination showed an entirely resected neuroendocrine tumor classified as typical carcinoid, and considering DIPNECH to be a preinvasive lesion, the therapeutic management consisted of serial imaging by computed tomography. During the last two years, no progression of either the pulmonary lesions or of the obstructive disease was observed.
Conclusion: DIPNECH is a rare, primary pulmonary process with proliferation of hyperplastic neuroendocrine cells, affecting principally middle-aged, non-smoking women. It is considered to be a precursor lesion to pulmonary carcinoid tumors. Given its only minor risk of invasive metastatic spread, serial imaging for timely detection of progressing lesions and optimizing of concomitant obstructive pulmonary disease are the preferred treatment approaches.
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