[Clinicopathologic features with pulmonary and tracheal glomus tumor: report of 8 cases]

Objective: To study the clinical and pathological features, immunophenotypes, molecular genetics characteristics, differential diagnosis, and prognostic factors of pulmonary and tracheal glomus tumors. Method: Eight cases of pulmonary and tracheal glomus tumors were collected in Jiangsu Provincial Hospital (including 1 consultation, from Gaochun People's Hospital, Nanjing, China) between May 2015 and April 2023, and their clinical and imaging data, pathological morphology, and immunohistochemical characteristics were retrospectively analyzed. Gene testing and follow-up were performed. Result: There were 5 males and 3 females with onset ages ranging from 29 to 75 years old, median age 63.5 years. Among the patients, 5 cases were located in the trachea and 3 cases in the lungs. Under light microscopy, 5 cases were benign glomus tumors with clear boundaries, diffuse sheet or nest-like distribution, small, round or short spindle-shaped tumor cells, rounded and centered nuclei, and no obvious nuclear mitosis was seen. Two cases of glomus tumor of uncertain malignant potential showed an infiltrative growth pattern involving smooth muscle, nerves and blood vessels with necrosis and calcification, the tumor cells were more uniform in size, round or short spindle-shaped nuclei, and no obvious nuclear mitosis was seen; One case of malignant glomus tumor was seen in sarcomatous areas, lung membrane invasion and necrosis, the tumor cells were highly heterogeneous, binucleated and multinucleated, with nuclear mitoses of 20/50 high power field (HPF), and pathologic nuclear mitoses were easy to be seen. Immunohistochemically, SMA, Calponin, H-caldesmon, Vimentin and Collagen Ⅳ were all positive (8/8). Some cases expressed Syn (3/8) and Bcl-2 (4/8). The Ki-67 proliferation index was 1-2% (7/8) and 40% (1/8). BRAF V600E were detected as wild-type (8/8), and no mutations were detected in exons 2, 3, and 4 of KRAS human EML4-ALK fusion gene were negative in 5 surgical cases. Case 6 showed HMBOX1-ALK gene fusion, TERT gene mutation and CDKN2A gene deletion, and case 8 showed CARMN-NOTCH2 gene fusion. Seven cases were followed up (8-103 months, median follow-up time 30 months), 1 case was lost, 1 case recurred 21 months after surgery, and others with no evidence of recurrence or metastasis. Conclusions: Pulmonary and tracheal glomus tumors are very rare and need to be differentiated from other common tumors by combining pathological morphology and immunohistochemistry. Maybe there are some differences in the malignant diagnostic criteria and molecular genetic characteristics between visceral derived glomus tumors and soft tissue derived tumors of the same kind, such as limbs and skin. More data accumulation is needed.