A 24-year-old Chinese woman with Graves' disease presented with myositis two months after treatment with carbimazole. The patient's myositis resolved with hydration and cessation of carbimazole. No other causes of myositis were found, and a change in the medication to propylthiouracil was uneventful. Review of the literature suggests a possible genetic susceptibility, as the majority of reported cases are Asian in origin, similar to patients who present with thyroid periodic paralysis. Changing the antithyroid drugs (ATDs) administered, decreasing the dose of pre-existing ATDs in the treatment regimen or addition of levothyroxine has been shown to result in clinical improvement of this complication. These observations suggest various mechanisms of carbimazole-induced myositis in the treatment of Graves' disease, including the direct effect of ATDs on myocytes, immune-related responses secondary to ATDs and rapid decrements in thyroid hormone with ensuing myositis.
Antithyroid Agents ; adverse effects ; Carbimazole ; adverse effects ; Female ; Genetic Predisposition to Disease ; Graves Disease ; drug therapy ; Humans ; Myositis ; chemically induced ; genetics ; therapy ; Young Adult

INTRODUCTIONWe aimed to compare the malignancy risk stratification of histologically proven thyroid nodules using the 2015 American Thyroid Association (ATA) Management Guidelines, 2014 British Thyroid Association (BTA) Guidelines for the Management of Thyroid Cancer and the Thyroid Imaging Reporting and Data System (TIRADS).

METHODSThyroid nodules measuring > 1 cm resected over 5.5 years were retrospectively studied. Demographic information as well as cytology and histopathology results were collected. Static ultrasonography (US) images and radiologists' reports of each resected nodules were reviewed and classified based on the above risk classification systems.

RESULTSA total of 167 thyroid nodules from 150 patients were examined. More malignant nodules were solid (78.4% vs. 62.5%; p = 0.049) or hypoechoic (70.6% vs. 28.6%; p < 0.001), and had irregular margins (35.3% vs. 8.0%; p < 0.001), taller-than-wide morphology (9.8% vs. 2.7%; p = 0.031), microcalcifications (33.3% vs. 8.0%; p < 0.001), disrupted rim calcifications (9.8% vs. 0.9%; p = 0.012) or associated abnormal cervical lymphadenopathy (13.7% vs. 0.9%; p = 0.001) compared with benign nodules. The guidelines' diagnostic performance was: ATA - sensitivity 98.0%, specificity 17.3%, positive predictive value (PPV) 35.0%, negative predictive value (NPV) 95.0%; BTA - sensitivity 90%, specificity 50.9%, PPV 45.5%, NPV 91.8%; and TIRADS - sensitivity 94.0%, specificity 28.2%, PPV 37.3%%, NPV 91.2%.

CONCLUSIONSonographic patterns outlined by the three guidelines displayed high sensitivity and NPV. Although isolated suspicious US features cannot predict malignancy risk, they should be considered when risk stratifying nodules that do not fit into particular sonographic patterns based on current guidelines.