[Clinicopathologic features of glomus tumor of the kidney]

Objective: To investigate the clinicopathologic and differential diagnostic features of glomus tumor of the kidney. Methods: Four cases of glomus tumor of the kidney were collected from the archives of Peking University Third Hospital, the Second Hospital of Tianjin Medical University, Ningbo Yinzhou Second Hospital and Zhejiang Provincial People's Hospital between January 2012 to June 2017; the clinical and radiologic features, histomorphology, immunohistochemistry, ultrastucture and prognosis were analyzed and the relevant literature was reviewed. Results: Patients consisted of 2 men and 2 women with ages ranging from 37 years to 66 years (mean 55 years). Three patients had history of hypertensive disease (grade Ⅱ, 3 to 10 years). The tumors measured in maximum diameter from 3.0 cm to 4.0 cm (mean 3.6 cm) and showed gray-white to yellow and tan on cut surface. Macroscopical examinations showed all tumors were circumscribed but non-encapsulated. Histologically, 1 tumor presented as glomus tumor with extensive myxoid change, 1 as cellular and solid pattern glomus tumor, 1 as glomangioma with focal myopericytoma-like pattern and 1 as symplastic glomus tumor with areas resembling myopericytoma. The tumor cells in two cases showed scant cytoplasm and uniform, bland-appearing nuclei without mitoses. In one case, the tumor cells were epithelioid with abundant eosinophilic cytoplasm and relatively well-defined cell borders. There was an increased mitosis of 4/50 HPF; however, no evidence of atypical mitosis or nuclear atypia was noted. In the symplastic glomus tumor the tumor cells showed frequently nuclear pleomorphism without mitoses. By immunohistochemistry, all tumors showed strong and diffuse reactivities to at least 3 of the 4 muscle-associated markers (SMA, h-Caldesmon, MSA and Calponin), 3 tumors strongly and diffusely expressed collagen Ⅳ, 2 expressed CD34 and 1 focally expressed desmin; whereas markers including epithelial, neuroendocrine, nephrogenic, melanoma-associated, STAT6, S-100 protein, CD117 and β-catenin all were negative in all the 4 tumors. Ultrastuctural analysis was done in 2 cases and showed prominent cytoplasmic actin bundles and pericellular basement membrane, and lacking of rhomboid renin crystals in both tumors. The hypertension persisted after surgical resection for all the 3 patients with this medical history. Follow-up information (range: 6-64 months, mean: 44 months)showed that no evidence of local recurrence or distant metastasis was identified in all 4 patients. Conclusions: Glomus tumor rarely occurs in the kidney and usually has a good prognosis. Careful attention to its morphology with the judicious use of immunohistochemistry and ultrastuctural analysis can be helpful for its diagnosis and differential diagnosis.