Diagnosis and Differential Diagnosis of Desmoplastic Fibroblastoma by Clinical, Radiological, and Histopathological Analyses

Background： Desmoplastic fibroblastoma （collagenous fibroma） is an uncommon benign soft-tissue tumor, rarely involving bone. It shares some overlapping features with other infiltrate tumors, such as desmoid-type fibromatosis, neurofibroma, and low-grade fibromyxoid sarcoma. The misdiagnosis may cause unnecessary surgical overtreatment, especially for those involving bone. In order to deepen the understanding of the diagnosis and differential diagnosis of desmoplastic fibroblastoma, we planned to analyze the clinical, radiological, and histopathological features and the outcome of desmoplastic fibroblastoma on the basis of case analysis and literature review. Methods： Sixteen cases were retrieved from the surgical pathology records from May 2011 to April 2016 in the Department of Pathology in Beijing Jishuitan Hospital. Formalin-fixed, paraffin-embedded specimens of 16 cases of desmoplastic fibroblastoma were collected. Hematoxylin and eosin stain and immunohistochemistry were used to observe the histological features of desmoplastic fibroblastoma of soft tissue and bone. The images for diagnosis obtained from the ultrasonic examination, X-ray, magnetic resonance imaging, and computed tomography were used to observe the radiological features. Related literatures were retrieved from the PubMed and CNKI databases. Results： Sixteen cases of desmoplastic fibroblastoma of soft tissue were located in the hand （n = 7）, loot （n = 4）, upper arm （n = 1）, shoulder （n = 1）, forearm （n = 2）, and one case occurred in the proximal femur. Age ranged from 32 to 82 years （median age： 58 years）. There were six females and ten males. Histologically, the lesions of soft tissue appeared as well-circumscribed masses with abundant collagenous matrix and low vascularity. Tumor cells were stellate- or spindle-shaped and uniformly distributed within the extracellular matrix. In five cases, the desmoplastic fibroblastoma were found to have infiltrated into the skeletal muscle tissue. In one case ofdesmoplastic fibroblastoma of bone, radiographs revealed osteolytically well-defined lesion, lmmunohistochemistry stain showed that vimentin and smooth muscle actin were positive in all cases of desmoplastic fibroblastoma. Conclusions： Desmoplastic fibroblastoma （collagenous fibroma） has prominent clinical, histopathological, and radiological features. Before the differential diagnosis from other tumors is obtained by thorough analysis and comparison of the similar and different characterist