A 20-years-old male presented to our Department of Orthopaedics with a complaint for a 7-years history of intermittent pain in the right proximal tibia in November 2009, obvious after activity and progressively worsening. Clinical examination revealed no apparent local tenderness or soft tissue mass, without swelling and ulceration, no limited motion of the right knee. Also, no lymph nodes swollen were found in the inguinal area of the patient. The patient had no previous history of radiation therapy and local infection of the right knee. Complete blood count, serum biochemistry panel, alkaline phosphatise, lactate dehydrogenese levels, serum calcium, phosphorus were all normal.
Adequate imaging examinations were performed that on the plain X-ray of the right knee revealed a mixed-density lesion, expansile ground-glass lesion, radiotransparent, well-contoured, centered and oblong along the longitudinal axis of the tibia, without periosteum reaction (Fig. 1-a). Axis view of a computed tomography (CT) showed a ground-glass lesion involving the right anterolateral proximal tibia with radiotransparent and pseudo-septum, consistent with fibrous dysplasia in combination with unicameral bone cyst (Fig. 1-b). The benign lesion was further characterized by magnetic resonance imaging (MRI) on T1-weighted and T2-weighted sagittal image which showed no soft tissue mass, edema and periosteal reaction outside the lesion (Fig. 1-c).
According to the clinical and imaging features of the patient, it seems obvious a benign bone tumor consensus of expert meeting without performing preoperative biopsy. No surgical indications of bone grafting or internal fixation for this 2cm diameter benign lesion with complete tibial cortex and very low risk for pathologic fracture. A simple intracapsular curettage and decompression of tumor lesions was adequate and performed soon after signed informed consent from the patient. In the operation, the lesion revealed about 5ml light yellow fluid in the cystic cavity, mixed a small amount of silt-like bone tissue and proliferative fibrous granulation tissue. After intracapsular curettage and decompression, the cyst wall of the lesion was treated with electric coagulation, intraoperative irrigation careful, and alcohol-inactivated furthermore. The initial samples from the lesion was scraped off for pathological examination and confirmed FD in combination with UBC one week after the intracapsular curettage surgery (Fig. 2-a) (Fig. 2-b). After the curettage surgery, Pain of the right knee quickly disappeared, the incision healed normally and function activities returned to normal during a regular follow-up postoperative after the curettage surgery. Review of X ray film showed 3 days postoperative (Fig. 2-c), progressive sclerosis of the lesion at six months after intracapsular curettage surgery (Fig. 2-d).
At two years follow – up after the initial curettage and decompression operation, the patient developed pain again and even worse at the original surgical area, accompanied by a 3*2cm soft tissue mass and tenderness locally. Radiography, CT and MRI of the right knee were immediately examined (Fig. 3-a), (Fig. 3-b), (Fig. 3-c). The radiological features were consistent with the obvious and typical appearance of osteosarcoma. CT-guided puncture biopsy on the recurrent lesion was performed immediately, but the pathological diagnosis reported fibrous tissue hyperplasia with hyalinosis in the upper segment of the right tibia. A further open biopsy seemed obviously necessary after expert meeting with great suspected whether the malignant transformation happened. Written informed consent was obtained from the patient. Post of the open biopsy, the histopathological evaluation revealed that the solid tumor section of soft tissue mass showing pleomorphic spindle cells, consistent with high-grade osteosarcoma, including hyperchromatic pleomorphic nuclei and numerous scattered mitotic figures (Fig. 3-d). Combined with definite clinical, imaging, histological and immunohistochemical findings, it was consistent with the diagnosis of osteosarcoma malignant transformation secondary to FD in combination with UBC.
The patient requested a limb salvage operation as soon as possible, neoadjuvant chemotherapy before surgery or radical surgical treatment of amputation was rejected. The patient underwent radical proximal tibial resection with tumor type endoprosthesis for the defect reconstruction (Fig. 4-a) (Fig. 4-b). Satisfactory limb function was obtained immediately after limb salvage operation. One course of neoadjuvant chemotherapy monthly was received postoperative with the cisplatin, ifosfamide and Adriamycin (DIA) chemotherapy regimen.
At two months follow – up after the limb salvage, there was a local recurrence of the right knee with a soft tissue mass, even multiple and unresectable lymph nodes distant metastases of the patient was certified in the right groin and pelvic cavity by Positron Emission Tomography-Computed Tomography (PET - CT) examination (Fig. 4-c). Two weeks of vitro radiotherapy in the groin region was received then. The patient developed multiple osteosarcoma metastases to his right lung, intrapulmonary lymph nodes, and right inguinal lymph nodes by re-examined PET – CT diagnosis at six months follow – up after the limb salvage. Unfortunately, the left frontal bone with soft tissue mass, invasion of the skull, intracranial invasion, and compression of brain parenchyma were found by cranial CT examination after eight months of the limb salvage (Fig. 4-d). During the last chemotherapy, the patient developed severe intracranial hypertension and was forced to stop the chemotherapy. After an successfully emergency brain edema and neurological functional recovery, the patient's vital signs recovered. Cancer hospice care eventually received and died eight months after the diagnosis of fibrous dysplasia in combination with unicameral bone cyst, its systemic multiple organ osteosarcoma metastasis was the leading cause of death for this young man.