[Clinicopathological characterization of primary pulmonary and tracheal glomus tumors]

Objective: To investigate the clinical pathological features of primary pulmonary and tracheal glomus tumors. Methods: The clinical and pathological features of 11 cases (4 cases from Shanghai Pulmonary Hospital, Tongji University School of Medicine, China and 7 cases from Fudan University Shanghai Cancer Center, China) of respiratory glomus tumor diagnosed from 2010 to 2019 were analyzed, and reviewed in light of the relevant literature. Results: In the 11 cases, there were 5 males and 6 females, with the onset ages of 29‒66 years (median age of 43). Six tumors were located in the lung, and 5 in the trachea. The tumor diameters ranged 1.0‒7.5 cm, with the average diameter of 2.6 cm. At low magnification, the tumors were diffuse or lobulated in shape. The tumor cells composed of sheets of oval to short spindle cells, with sharply defined cell border and prominent branching thin-walled vessels. Among the 4 benign glomus tumors, one was classified as benign symplastic glomus tumor owing to the hyperchromatic or degeneration nuclei. Two cases were classified as glomus tumors of uncertain malignant potential, on the account of cellular atypia and rare atypical mitotic figures. Five cases were classified as malignant glomus tumors, owing to the tumor necrosis, vascular invasion, marked nuclear atypia, prominent nucleoli and brisk mitoses (2-20/10HPF) including pathological mitotic figures. The tumor cells showed strong immunostaining for SMA, vimentin, type Ⅳ collagen and caldesmon to different extents, while CD34, cytokeratin and S-100 stains were negative. One of the cases was positive for desmin, and one case positive for synaptophysin. Follow-up information was available in 8 patients with the duration ranging from 6 to 95 months. At the end of the follow-up, 6 patients were alive without recurrence or metastasis, and two of the patients with malignant glomus tumors died. Conclusions: Primary pulmonary and tracheal glomus tumors is rare. Among the reported cases, malignant glomus tumor is the most frequent, followed by benign glomus tumors and uncertain malignant potential glomus tumors. Glomus tumors show sheet-like growth pattern and clusters of round epithelioid cells with numerous vascular spaces. They can be easily misdiagnosed as carcinoid tumor. The final diagnosis should be combined with immunohistochemical staining, such as SMA, caldesmon and vimentin.