Suture Granuloma and Surgical Clips as a Mimic of Thyroid Cancer Recurrence.

Case Presentation

A 59-year-old White man with pT3N0M0 multifocal papillary thyroid cancer, status post total thyroidectomy followed by radioactive iodine treatment (81.3 mCi), without evidence of recurrence for 6 years, presented with a 3-month history of a palpable neck mass. Physical examination revealed bilateral palpable neck nodules. Previous laboratory values demonstrated normal thyroid-stimulating hormone (TSH) and undetectable thyroglobulin level (TSH, 0.87 μU/mL; thyroglobulin, <0.1 ng/mL). Neck ultrasound (Fig. 1) and computed tomography (CT) scan (not shown) revealed bilateral neck masses interpreted as concerning for thyroid cancer recurrence. Outside-hospital fine-needle aspiration of both masses was consistent with recurrent thyroid cancer. Upon presentation to our facility, a positron emission tomography (PET)/CT scan (Fig. 2) was obtained and demonstrated 3 hypermetabolic nodules in the thyroid fossa without distant metastases. These nodules were not avid on radioactive iodine scan (not shown) when completed simultaneously with PET/CT. Laboratory values during withdrawal scans showed an undetectable thyroglobulin level (<0.1 ng/mL), an elevated TSH (33.1 μU/mL), and negative thyroglobulin antibodies. The outside-hospital pathology was reviewed at our institution, and the cytology was found to be consistent with atypical histiocytoid cells in the setting of acute inflammation.

Fig. 1

Fig. 2

What is the diagnosis?

Answer

Postoperative surgical clips and suture granuloma. Repeat thyroid ultrasound was performed and demonstrated bilateral lobulated central neck masses with calcification suggestive of postoperative suture granulomas and surgical clips. Repeat fine-needle aspiration of the 2 concerning central neck nodules again revealed abundant histocytes, multinuclear giant cells, and increased vascularity in the background of inflammatory cells and necrotic debris, with negative staining for neoplastic epithelial cells, consistent with a granulomatous process (Fig. 3). The case was reviewed with a multidisciplinary group that agreed the presentation was consistent with inflammatory response and suture granulomas related to the previous thyroidectomy. The clinical observation was recommended in this patient with serial physical examinations, ultrasounds, and biochemical testing with thyroglobulin/thyroglobulin antibody levels. Making the diagnosis was particularly challenging in this case. While an undetectable thyroglobulin level, an unremarkable iodine scan, and the findings on pathology were all reassuring, those results were discordant with the avidity seen on PET/CT that favored malignancy, highlighting the role of neck ultrasound to complement the workup. This case demonstrates that suture granulomas and surgical clips from prior surgery can imitate recurrent malignancy on thyroid ultrasound and 18F-fluorodeoxyglucose PET/CT. Suture granulomas are benign inflammatory lesions formed because of the nonabsorbable sutures used in thyroidectomy cases. Surgical clips also have a bright linear appearance which can look like calcification. Other mimics of recurrence on neck ultrasound include chronic granulomatous lesion, traumatic neuroma, reactive lymph node, and cervical thymus. Ultrasonographers, radiologists, and clinicians should be familiar with these sonographic cancer mimics, especially in postoperative patients. Additionally, inflammation in the head and neck is known to be 18F-fluorodeoxyglucose-avid, so care must be taken during PET scan interpretation.

Fig. 3

Disclosure

The authors have no multiplicity of interest to disclose.