En bloc resection and bone graft: does it alter the natural history of monostotic expansile fibrous dysplasia in children?

A 2.5-year-old boy presented to the authors’ clinic with his parents in July 2005, with a 3-month history of a firm lump and bowing deformity on his right forearm. The parents reported that the appearance of the boy’s right forearm was asymmetrical compared with the left one, and the deformity had gradually progressed during the past 3 months. No notable pain was noted. The boy had a normal physical development and denied any traumatic and medical history. The physical examination revealed the middle forearm was tumid and bowing on the ulnar and dorsal side. The patient had full range of motion on his shoulders, elbows, wrists and fingers except for a limited rotation motion on the right forearm which was 80 degrees of supination and 45 degrees of pronation. There was no tenderness to palpation over the right ulna, and the neurovascular examination was normal. The child appeared in good health on other systems.Radiographs of his right forearm showed a large expansile lucent lesion in the diaphysis of the ulna, extending to the proximal and distal metaphysis (Figure 1A). The lesion presented as fusiform-shaped and typical “ground-glass” appearance with a size of 5.7 cm in length and 1.9 cm in maximal width. The computed tomography (CT) scan indicated it had a well defined circumscription and no calcification and bone septums were seen. The cortex showed marked expansion and thinning without periosteal reaction. The density in the area of lesion was homogeneous and the CT value was an average 123 Hu, which was similar to the density of the cancellous bone, but without the visible trabecula of bone (Figure 1B,C). No distinct soft tissue mass was exhibited on the radiographic or CT images. The laboratory tests, including complete blood cell count, thyroid function, liver and renal functions, were within normal limits.Based on the clinical and typical image presentations, a diagnosis of monostotic fibrous dysplasia was established without performing an incisional biopsy. In view of the deformity progressing and limited rotation motion on the right forearm, an en bloc resection of the lesion and autogenous fibular graft was carried out. At surgery, the right ulna was exposed subperiosteally, and the lesion was excised en bloc with preservation of the proximal and distal healthy metaphysis. Then the bone defect was reconstructed using the free autogenous fibula of the ipsilateral lower leg and the intramedullary fixation was achieved with a 2.0 mm Kirschner wire. A postoperative cast was employed to immobilize the elbow and forearm in a neutral position. The excised gross sample revealed the cortical bone was thin and firm except for a small perforation on the upper pole. The medullary cavity of the ulna was replaced by a solid grey white expansile mass. The histological examination confirmed the diagnosis of fibrous dysplasia (Figure 2).Six weeks after surgery, the patient had a well grafted union and the pin and cast were removed (Figure 3A). No early complications were seen. At 3-month follow up, he had regained the full range of rotation movement on his right forearm. However, 4 years postoperatively, the patient returned to the authors’ clinic for a reappeared deformity on his right forearm. A subsequent radiograph was taken and demonstrated a long, expansile lytic lesion in the middle and proximal ulna surrounded by an irregular thin bone shell, indicating recurrence of the tumor (Figure 3B). The lesion was enlarged and extended proximally to the coronal process level. The bowing deformity in the ulna, as well as in the radius was more severe than the initial presentations. On being informed of the natural history of fibrous dysplasia, the parents refused further treatment and determined to observe. At the last follow-up, 8 years postoperatively, the lesion and the deformity in the ulna had been further progressive, but there was no evidence of malignant transformation (Figure 3C).

A 6-year-old boy reported increased left lower leg pain for 1 month before presenting to the authors’ hospital. The mother observed that his pain was relieved by rest and was aggravated by activity, especially running and playing football. The pain had gradually worsened in the recent week, and there was no pain elsewhere. No analgetica or anti-inflammatory medication was used. The patient had a normal developmental history and denied any family or systematic disease history. On physical examination, the boy appeared in good health. There was mild swelling on the lateral side of the left lower leg. The patient reported a moderate tenderness when palpated over the left fibula, with no radiation of the pain. He had full range of motion on the ankles, knees and hip joints. The gait was normal and no neurovascular abnormality was noted. The posteroanterior radiograph of the left lower leg revealed a 9.0 cm long, expansile lesion in the middle fibula with resembling multiseptated, ground glass lucencies (Figure 4A). Both sides of the cortex were thinning but there was no periosteal proliferation. The radiological features showed a benign lesion of the fibula.Subsequently, the boy underwent an en bloc resection of the fibular lesion and reconstruction with autogenous iliac bone graft. An intramedullary fixation with a 2.0 mm Kirschner wire was used to maintain the alignment of the reconstructed fibula. The postoperative pathological examination showed typical histological findings of fibrous dysplasia. Eight weeks after surgery, the grafted bone had united with the preserved proximal and distal metaphysis, and the Kirschner wire was removed (Figure 4B). At postoperative 4.5-month follow-up, the radiographs of the left lower leg demonstrated there were multiple small irregular lucencies in the fibula (Figure 4C). The extent of the lucencies was similar to the original lesion. Furthermore, in the subsequent 4.5 years of follow-up, these small cystic components had gradually fused into a long, expansile lesion and appeared progressive over time (Figure 4D,E).