[Calcifying fibrous tumor: a clinicopathological analysis of 32 cases]

Objective: To investigate the clinicopathological characteristics, histogenesis, immunophenotypes, molecular genetic characteristics, diagnosis and differential diagnosis of calcifying fibrous tumors (CFT). Methods: A total of 32 cases of CFT (22 cases from Henan Provincial People's Hospital and 10 cases from PLA Army Medical Center) diagnosed between June 2009 and February 2019 were reviewed. The clinical and pathologic data were analyzed. Results: There were 12 male and 20 female patients, aged from 15 to 63 years (mean 40.8 years). Eleven cases occurred in stomach, four cases in retroperitoneum, four cases in ovary, two cases in scrotum, two cases in mediastinum, two cases in head and neck, one case each in thoracic cavity, lung, adrenal gland, kidney, sigmoid colon, epididymis and mesosalpinx. All the tumors were solid masses with clear boundaries. The maximal dimension of the tumors ranged from 0.6 to 10.0 cm. Microscopically, there was hypocellular stromal sclerosis and wavy storiform coarse collagen with superimposed scattered or patchy lymphocytes and plasma cells; calcification or gravel formation were also detected. Immunohistochemistry showed that spindle cells were positive for vimentin and some were positive for CD34; and they were negative for calponin, SMA, desmin, S-100 protein, SOX10, STAT6, β-catenin, ALK, CD117, DOG1, CKpan, and EMA. No ALK rearrangement was detected by FISH in all cases. No C-KIT and PDGFRA mutation was detected in all the tested 11 cases of stomach, four cases of retroperitoneal and one case of sigmoid colon CFT. MDM2 was not amplified by FISH in all four tested cases of retroperitoneal CFT. Conclusions: CFT is a rare benign tumor of fibroblastic cell origin. The diagnosis mainly depends on histomorphologic analysis and immunophenotyping. CFT should be differentiated from other benign and malignant spindle cell mesenchymal tumors.