Collagenous Fibroma at the Surgical Site after Thyroidectomy for Papillary Thyroid Carcinoma

Collagenous fibroma (CF) is a rare benign tumor that occurs at various anatomical sites including the head and neck. CFs are often omitted from differential diagnosis before surgery. We describe a case of CF in a 54-year-old male who presented with a growing neck mass of 1-year duration at the site of previous right hemithyroidectomy for papillary thyroid carcinoma (PTC). Although radiologic findings demonstrated a benign tumor, surgical excision was carried out per patient’s preference and to rule out recurrent thyroid cancer. The mass was severely adherent to the surrounding muscles, but was resected completely without any injury to the adjacent structures. Histological studies revealed CF. The postoperative course was uneventful without vocal fold paralysis. CFs can be a diagnostic challenge in preoperative evaluation. Conservative excision was sufficient in most cases without recurrence. Clinicians should be aware of CFs in diagnosis, especially in postoperative site.