Prognosis of Adamantinoma of Long Bones: A Long-Term Follow-Up Study

Background Adamantinoma of long tubular bones is a rare primary malignant bone tumor. According to the literature, different prognosis and recurrence rates have been reported. Objectives The purpose of this case series study was to evaluate the clinical behavior and prognostic features of adamantinoma of long bones. Patients and Methods In this study, 13 histologically proven cases of adamantinoma of long bones which were treated in our hospital during March 1977 to June 2015 were evaluated. The mean follow-up period was 72 ± 44.4 months. The male:female ratio was 10:3, aged between 13 and 63 years at the time of diagnosis (mean = 24.8 ± 13.1 years). There was a period between the onset of disease and definite diagnosis (mean: 17.5 ± 14.7 months). In two cases according to the imaging and clinical symptoms the lesion seemed to be osteofibrous dysplasia, but during the follow-up, the diagnosis was changed to adamantinoma when open biopsy and pathologic assessment were performed. In 10 cases the tumor was located in the tibial diaphysis, in two cases the location was the distal shaft of the femur, and in one case the location was proximal of the humerus. All the cases underwent wide resection and intercalary or osteoarticular allograft reconstruction as the main surgery after primary incisional biopsy. Results In eight cases, at least one local recurrence happened in an average 33.4-month period after the wide resection. In four of these patients rather than one local recurrence was occurred, but in one patient despite pulmonary metastasis the patient underwent pulmonary lobectomy and was alive at the end of the study. Allograft-related complications happened in five cases (two infections, one osteoarthritis of ankle, and two allograft fractures). For five patients ultimately recurrence and complication lead to amputation. Six patients died because of this disease, in all of which pulmonary metastasis occurred. The five-year survival rate in this study was 69%. Conclusions Adamantinoma of long bone is a low-grade malignant tumor; however, wide resection tends to local recurrence and metastasis to the lung. Recurrence and metastasis can occur many years after surgery and there is a long disease-free period between the first wide resection and first recurrence and metastasis. This study underlined that despite the low-grade pathologic feature of this tumor, its behavior is like a high grade sarcoma and it may be better to perform sufficient wide resection at the first surgery with wide clear margin to reduce the rate of recurrence, but this approach needs to be assessed by prospective studies. According to clear wide margins for all of our cases, we guess this high interest for recurrence may be due to skip lesions of this tumor along the affected bone or even in the neighbor bones.