Successful Treatment of a Massive Desmoplastic Fibroma of the Ilium without Surgery: A Case Report with Long-Term Follow-Up

Abstract

Desmoplastic fibroma of the bone (DFB) is a notably rare, lytic, locally aggressive but nonmetastatic, primary benign bone tumor in patients less than 30 years old. As the recommended primary treatment for DFB, wide resection is preferred to curettage from the perspective of recurrence but wide resection of DFB in the pelvis such as in the acetabulum could result in greater functional loss, suggesting the need for conservative treatments. However, there is no report on long-term follow-up following conservative treatment for DFB. The present case involved a 21-year-old woman with right hip pain. Radiological evaluation revealed a massive lesion throughout the right ilium and acetabulum with partial osteolysis, cortical destruction, marginal sclerosis, slight pseudotrabeculation, and bone expansion. Open biopsy from the ilium showed the proliferation of spindle cells in an abundant collagenous matrix without atypia and mitosis, suggesting a diagnosis of DFB. Conservative treatment was selected considering the risk of greater functional loss following wide ilium resection. An evaluation 10 years after follow-up showed a partially sclerotic lesion of the ilium and the absence of pain. The current case demonstrates that conservative therapy may be effective even in some cases of aggressive DFB.

Figure 1

(a, b) Radiography and three-dimensional computed tomography (3D-CT) reconstruction showed an osteolytic lesion of the right ilium and acetabulum with cortical destruction, marginal sclerosis, slight pseudotrabeculation, and bone expansion (arrowhead). (a) Radiograph. (b) 3D-CT. (c, d) Magnetic resonance imaging revealed a massive tumor lesion throughout the right ilium; T2-weighted images of the ilium lesion showed low-signal intensity compared to muscle (arrowhead). (c) Axial view. (d) Coronal view.

Figure 2

(a) The hematoxylin and eosin staining of specimen from the ilium showed the proliferation of spindle cells in an abundant collagenous matrix and involvement of tumor cells in the bone cortex, inducing bone destruction. (b, c) Immunohistochemically, the specimen was positive for cytoplasmic vimentin and smooth muscle action (SMA). (b) Vimentin. (c) SMA.

Figure 3

(a, b) Coronal view of computed tomography image at 10 years after the first visit revealed a partially sclerotic lesion of the ilium and acetabulum. (a) At first visit. (b) Ten years after the first visit.