We report a case of desmoplastic fibroma of the left femur. The patient was a 26-year-old male, presenting dull pain mass in his left thigh. Serological examination was within normal range. An osteolytic lesion existed in the medial condyle of the left femur, but no periosteal reaction was found radiographically. Computed tomography revealed a lesion in the posterior cortex of the medial femoral condyle, extending into the soft tissue. The tumor revealed low intensity in T1-weighted imaging and high intensity in T2-weighted imaging in MRI.
Biopsy samples indicated a desmoplastic fibroma as its pathological diagnosis. Curettage and bone grafting were thus performed. The sections microscopically showed fascicles of spindle cells separated by abundant collagen fibers. Cellularity was not high. Destructed bone and osteoid were seen at the periphery of the tumor, which was considered to be reactive change. Immunohistochemically, the tumor cells were positive for vimentin, and some were positive for α-SMA, S-100 and CD34 were negative.
Based on these findings, the histological diagnosis of desmoplastic fibroma was established.
Three months after surgery, the patient showed no local recurrence or metastasis. Since desmoplastic fibroma is reported to show local recurrence at the rate of 30% to 60%, careful follow-up is needed.
