Glomus tumor of uncertain malignant potential of the lung: a case report and review of literature.

Glomus tumor is an uncommon tumor usually presenting in the dermis. Rarely, it occurred in visceral organs including stomach, liver and long. The majority of glomus tumors were benign. Herein, we present a case of glomus tumor located in the left lobe of the lung in a 49 year-old Chinese male. An irregular mass measuring 3 cm was detected by imaging examination because of his suffering from cough, dyspnea and chest pain. Histologically, the tumor is composed predominantly of sheets of ovoid to round cells with clear border, pale cytoplasm and fine granular chromatin. The mitotic count was less than 5 per 50 HPF. The tumor focally invaded the surrounding normal bronchial and alveolar tissue. Immunohistochemical staining showed that the cells were diffusely positive for SMA, caldesmon, and vimentin. The Ki-67 proliferation index was approximately 20%. Based on morphologic features and the immunohistochemical profile, the tumor was consistent with glomus tumor of uncertain malignant potential.