Incidental cancer in multinodular goiter post thyroidectomy

Abstract

The risk of malignancy in the background of multinodular goitre (MNG) approximates 7.2%. The gold standard for diagnosis of thyroid cancer is fine needle aspiration (FNA). Unsuccessful, inconclusive or suspicious result mandate further investigations. The concern is on benign FNA which would not necessitate thyroidectomy but carries a risk of missed malignancy. Aim To determine the percentage and histopathological subtype of incidental cancers in patients who had thyroidectomy for multinodular goitre (MNG). Method Records of patients who underwent thyroidectomy between January 2005 and December 2010 at Chris Hani Baragwanath Academic Hospital were retrospectively reviewed. Data retrieved included patients’ demography, type of thyroidectomy, thyroid function test, FNA cytology and final histopathological results. Results A total of 166 thyroidectomies were performed on 162 patients. Majority (139) of patients were females. The mean age was 46 years (ranging from 15 to 79 years). A total of 120 pre-operative FNAs were available for analysis and 78 FNA were suggestive of benign nodular goitre. 70 of benign FNA results were histologically confirmed to be MNG after thyroidectomy. Incidental malignancy was found in 4 out of 70 cases of MNG (5.7 %); all were papillary carcinomas and predominantly (75%) follicular variant. Conclusion The risk of missing cancer in the background of MNG was 5.7%. The commonest histological type of thyroid cancer found in MNG was papillary carcinoma (100%) with follicular variant being the most common subtype (75%).