Clinical Significance and Prognostic Impact of Subcutaneous or Intrastrap Muscular Recurrence of Papillary Thyroid Carcinoma

Subcutaneous or intrastrap muscular (SIM) recurrence is rare in papillary thyroid carcinoma (PTC) patients, and its clinical significance remains unclear. We analyzed 29 patients with PTC who showed SIM recurrence in order to elucidate this issue. The incidence of patient age 55 years or older at initial surgery, extrathyroid extension, and clinically detected lymph node metastasis was 83%, 35%, and 46%, respectively. After surgical dissection, 17% of patients showed repeated SIM recurrence. Distant recurrence was detected in 45% of patients and was more likely to occur in patients with high-risk clinicopathological features. In all but one patient in this series, distant recurrence was detected at the same time or after the detection of SIM recurrence. Three patients died of PTC, but none of these patients died of the development of recurrent SIM lesions. These findings suggest that although SIM recurrence is a rare event and is not fatal, it is a predictor of distant recurrence especially in patients with high-risk clinicopathological features. Careful followup is recommended for such patients.