[Desmoplastic fibroblastoma: a clinicopathologic analysis of 7 cases].

Objective: To investigate the clinical features, immunohistochemical and differential diagnosis of desmoplastic fibroblastoma. Methods: The clinical data and pathology features of 7 cases of desmoplastic fibroblastoma were collected and immunohistochemical study were carried out in all cases with a review of the literatures. Results: There were 2 males and 5 females, with age ranging from 31 to 71 years (average and mean age were 59 and 61 years, respectively). The tumors were located in extremities and abdomen (left toe and right toe, right foot back, left leg and right thigh, right forearm and left hepatic lobe). Clinically, the tumors presented as slow growing painless masses of long standing duration. Grossly, the tumors were well-circumscribed with firm, white to gray cut-off surface. Tumor size ranged from 1.2 to 4.0 cm in maximum diameter (average 3.0 cm). Microscopically, 2 cases were located in dermis, 4 cases were located in subcutaneous and 1 case was located in liver parenchyma. It was composed of spindle-shaped or stellate cells with a fibroblastic or myofibroblastic appearance, and sparsely scattered in densely fibrous or fibromyxoid background. There was small vascular component in tumor background. At high magnification, the tumor cells were medium size with abundant cytoplasm, and the nucleus were small and always with small nucleoli. In some cases, the tumor cells were slightly larger with enlarged nuclei, but without cellular atypical and mitosis. Immunohistochemical study showed that the tumor cells were strongly positive for vimentin, desmin, S-100 protein and CD34, but CKpan was negative. α-SMA showed focal positive in one case. Ki-67 index ranged from 1% to 2%. Four cases were followed-up (ranged from 11 to 21 months, average 16.5 months) and the patients had no recurrence after surgery. Conclusions: Desmoplastic firoblastoma is a rare soft benign tumor. The differential diagnosis includes other benign or low-grade fibroblastic/myofibroblastic lesions.