M. Manasa1, O. Picado1, M. L. Mao1, R. Minami1, J. C. Farra1, J. I. Lew1 1University Of Miami Leonard M. Miller School Of Medicine,Division Of Endocrine Surgery, DeWitt Daughtry Family, Department Of Surgery,Miami, FL, USA
Introduction: Patients with benign thyroid disease undergo thyroidectomy for a variety of reasons including compressive symptoms, hyperthyroidism and cosmesis. Although patients are referred for benign disease, underlying thyroid malignancy may be incidentally discovered on final pathology. This study examines the association between benign indication for thyroid surgery and incidental thyroid cancer.
Methods: A retrospective review of 1,040 patients undergoing thyroid surgery at a tertiary referral center was performed. Surgical indications for benign thyroid disease (n=357) included compressive symptoms, hyperthyroidism, goiter size >4 cm, substernal goiter, cosmesis, and patient preference. A dominant or “index” thyroid nodule was defined as a nodule >1 cm or the largest/most suspicious thyroid nodule in a multinodular goiter (MNG). An “incidental” thyroid carcinoma was defined as any cancer incidentally discovered outside the index nodule. Patients with previous thyroid surgery, indeterminate or malignant preoperative FNA results were excluded.
Results: Of 916 patients who underwent thyroidectomy, 559 were referred for malignancy and 357 for benign disease. Patients with benign disease were referred most commonly for non-toxic MNG (n=223, 63%) followed by Graves’ disease (n=46, 13%), non-toxic solitary nodule (n=40, 11%), toxic MNG (n=32, 9%), and substernal goiter (n=16, 4%). Final pathology demonstrated incidental thyroid carcinoma in 97 patients (27%): 39 (40%) had a malignant index nodule, 36 (37%) had incidental thyroid carcinoma, and 23 (23%) had both index and incidental malignancy. The median size of malignant index nodules was 2 cm (range: 0.1-6 cm) and the median size of incidental carcinomas was 0.4 cm (range: 0.1-5.8 cm). Lymphovascular invasion was present in 20% (19/97) and extrathyroidal extension was present in 8% (8/97) of patients. Patients with non-toxic solitary nodule (n=18, 45%) most commonly had incidental carcinoma followed by non-toxic MNG (n=69, 31%), substernal goiter (n=4, 25%), toxic MNG (n=5, 16%) and Graves’ disease (n=4, 9%). The most common malignancy found on final pathology was papillary thyroid carcinoma (PTC, n=93, 96%) followed by follicular (n=2, 2%), medullary (n=1, 1%), and anaplastic (n=1, 1%) thyroid cancer. The majority of PTC were follicular variant (n=69, 74%) followed by classical (n=20, 22%), tall cell (n=2, 2%), and diffuse sclerosing (n=2, 2%) variants.
Conclusion: Patients undergoing surgery for benign thyroid disease have significant rates of occult malignancy on final pathology. Despite these high rates of underlying malignancy, the majority of these tumors are low risk thyroid malignancies based on American Thyroid Association risk stratification and thus do not warrant further extensive surgical or clinical management. Nevertheless, careful evaluation and counseling by a surgeon may be necessary in managing patients with benign thyroid disease.