Pattern of Recurrence of Myxofibrosarcoma is not Associated with Pattern at Presentation or Rate of Delayed Diagnosis

The tendency of myxofibrosarcoma (MFS) to have a non-nodular appearance on magnetic resonance imaging (MRI) may present a challenge in detection of local recurrence. Appropriate index of suspicion of expected imaging appearance can alleviate this challenge. Our objectives were to determine if: 1) imaging pattern at recurrence is associated with delayed diagnosis, and 2) appearance at recurrence can be predicted based on appearance at presentation. A retrospective cohort study was performed. Two analysis groups were used: patients with recurrence captured on MRI (objective 1) and patients with MRI prior to resection and at recurrence (objective 2). Three radiologists scored images independently and in consensus as infiltrative (tail-like spread), focal (absence of spread), or mixed. Consensus results were used for analysis with Fisher’s exact test. There was substantial agreement among the 3 readers (k = 0.72, 95% confidence interval: 0.59 - 0.85). Half of all infiltrative cases were associated with a delay in diagnosis, compared to 10% of mixed or focal cases; however, there was no statistically significant association between infiltrative pattern at recurrence and delayed diagnosis (P = 0.08). In 70% of cases, recurrence had the same appearance as presentation, suggesting a trend; however, there was no association between appearance at baseline and recurrence (P = 0.1). Imaging appearance at baseline does not reliably predict imaging appearance at recurrence. Therefore, a high index of suspicion for the infiltrative pattern is required in assessment of post-operative MRIs in patients with MFS.