Long-term outcome following treatment of Adamantinoma and Osteofibrous dysplasia of long bones

Introduction: Adamantinoma (AD) is an ultimately rare, low-grade malignant bone tumor. In most cases it occurs in the tibia of young adults. Osteofibrous dysplasia (OFD) is a rare, benign, lesion that is typically seen in children. Histopathology, ultrastructure, and cytogenetics indicate that these lesions are closely related. Yet, etiology remains a matter of debate. Local recurrence rates are high for both entities as published in literature and long-term outcomes are scarce, due to the rarity of the disease.

Hypothesis: AD should be treated by En-Bloc resection while ODF can be treated by curettage or by observation. Consequently, the aim of the present study was to answer following questions: Were local recurrence rates of both entities different based on a retrospective review within a tertiary referral center for orthopedic oncology?

Material and methods: In a retrospective cohort study, 10 patients with AD and 5 patients with OFD (including 1 patient with OFD-like-AD) were reviewed. Primary surgeries for patients with AD were: En-bloc resection in 7, curettage in 2 and amputation in 1. In the OFD group, only 2 patients underwent surgery by curettage. Mean follow-up was 16 years (range: 2-47 years). Nine patients had a minimum follow-up of 10 years (mean: 23 years; range: 10-47 years).

Results: Four patients with AD (40%) and 2 patients with OFD (40%) - all of them following surgical removal - suffered from local recurrence. In the "En bloc" resection group of AD, there were 2 LR (29%). All patients of both groups treated with curettage showed LR. One patient with AD had metastasis at time of diagnosis and died of disease. Another patient with AD was diagnosed with metastasis 67 months after surgery and was still alive with disease at latest follow-up (77 month).

Discussion: The overall prognosis of AD and OFD is good, yet local recurrence rates are high, irrespective of surgical strategy. While an internationally standardized treatment regime is still missing, a more radical surgical approach should be considered, especially when treating AD.

Level of evidence: Retrospective study; Level IV.