PMC5061071_01
Radiological, endoscopic, and macroscopic findings. (a) Contrast-enhanced chest CT reveals a water density mass in the left main bronchus (arrows). (b) Bronchoscopy shows a white polypoid mass filling the left main bronchial lumen. (c, d) The tip of the endobronchial tumor partially resected by endoscopic snaring procedure. The surface of the tumor is smooth, and the cut-surface is tan in color. (e-g) Formalin-fixed bronchopulmonary tissue obtained by left lower lobe segmental resection. A cylindrical mass arises from the superior segmental B6a/b crista and enlarged the lumen of B6, B6a, and B6b.
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Chest CT examination revealed a left lower lobe atelectasis with a water density mass in the left bronchus (Fig. 1a). Upon initial bronchoscopic examination, a polypoid tumor was observed that occluded nearly 90% of the lumen of the left main bronchus (Fig. 1b). The partially resected surgical specimen consisted of tumor tissue that measured 1.5 cm in diameter (Fig. 1c). The tumor was well-circumscribed, firm, and tan in color (Fig. 1d). Grossly, the tumor was a firm cylindrical mass measuring 2.6 cm in length and 1.4 cm in diameter, which arose from the superior segmental B6a/b crista and filled and enlarged the lumen of B6, B6a, and B6b (Fig. 1e-g).
Histological and immunohistochemical findings. (a) The tumor was composed of sheets of oval to cuboidal cells. Numerous vascular spaces are observed in the tumor. Characteristically, tumor cells are constituents of the neoplastic vascular walls. H&E stain, original magnification x200. (b) The tumor cells are bland and uniformly monotonous with a centrally placed round nucleus. There are no chromatin increment, obvious nucleoli, or mitotic figures. H&E stain, original magnification x400. (c) The tumor cells are strongly immunoreactive for anti-alpha-smooth muscle actin antibody. Original magnification x200. (d) A portion of tumor cells are also immunoreactive for anti-calponin antibody. Original magnification x200. (e) The individual tumor cell is surrounded by positive immunostaining for anti-type IV collagen antibody. Original magnification x400. (f) Silver impregnation shows an intricate chicken-wire pattern between tumor cells, representing basement membrane material. Original magnification x400.
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Abundant vascular spaces were observed in the tumor, and some were surrounded by tumor cells (Fig. 2a). The tumor cells were uniformly monotonous with a centrally placed round nucleus and amphophilic to lightly eosinophilic cytoplasm (Fig. 2b). Immunohistochemically, the tumor cells exhibited cytoplasmic positivity for alpha-smooth muscle actin, calponin, and vimentin (Fig. 2c and d). The individual tumor cells were surrounded by positive staining for silver impregnation and anti-type IV collagen antibody, which showed an intricate chicken-wire pattern representing basement membrane material (Fig. 2e and f).