Neuroendocrine tumor secondary to pulmonary hypoplasia: A case report

Abstract

Pulmonary hypoplasia is diagnosed during the perinatal period and is a cause of death in newborns. However, these developmental abnormalities are diagnosed in adulthood in some cases. A 70-year-old male smoker was diagnosed with stage IIIA pulmonary adenocarcinoma in the right upper lobe with right middle lobe hypoplasia. He subsequently underwent right upper and middle lobectomy with lymph node dissection by video-assisted thoracoscopic surgery. In addition to an invasive adenocarcinoma in the right upper lobe, pathological examination of the hypoplastic lobe revealed neuroendocrine hyperplasia, as well as tumorlets and a typical carcinoid. Eight cases of pulmonary neuroendocrine tumors that developed from pulmonary hypoplasia have been reported to date. Interestingly, all but one case occurred in the right middle lobe. Neuroendocrine cell hyperplasia has been reported to develop in hypoplastic lungs postnatally; therefore, we speculated that the lesion was the origin of these neuroendocrine tumors. Moreover, the pathological findings suggested that atelectasis was involved in the pathogenesis of this rare condition. In adults, when lobar hypoplasia is diagnosed, neuroendocrine tumors should be anticipated.

Keywords: carcinoid; neuroendocrine cell hyperplasia; pulmonary hypoplasia; tumorlet.

FIGURE 1

(a) Contrast‐enhanced computed tomography (CE‐CT) showing a 32 mm irregular nodule in the posterior segment (S2) of the upper lobe of the right lung. (b) A small‐sized right middle lobe is detected on computed tomography (white arrowhead). The arrowhead indicates the atelectatic region. (c) Bronchoscopy revealing no abnormal findings in the bifurcation of the right middle lobe bronchus (B4 and B5)

FIGURE 2

(a) Macroscopic findings showing a 4.0 cm diameter tumor in the upper lobe of the right lung. (b) Macroscopic findings of the tumor. The pathological diagnosis is a moderately invasive adenocarcinoma with acinar predominantly showing a mucinous cribriform pattern. Scale bar, 500 μm. (c) Metastasis in a right lower paratracheal node (station 4R). Scale bar, 500 μm

FIGURE 3

(a) Macroscopic findings in the right upper and lower lobes. The middle lobe (black arrows, 6 cm) is much smaller than the upper lobe and is diagnosed as hypoplasia. (b) Neuroendocrine cell hyperplasia (circled), tumorlets (arrowheads), and a typical carcinoid (delineated by broken line) are observed in a Loupe view using hematoxylin–eosin (HE) staining. (c) Microscopic findings of the carcinoid. The tumor has a monotonous small ovoid chromatin pattern without mitosis. Little necrosis is observed. Scale bar, 200 μm. (d) Pathological findings of the tumorlets. The lesions are less than 5 mm. Scale bar, 200 μm. (e) Microscopic findings of the neuroendocrine cell hyperplasia. The foci are limited to the bronchiole. Scale bar, 200 μm