The efficacy of percutaneous tetracycline instillation for sclerosis of recurrent thyroid cysts: a multivariate...

A dichotomy exists in the literature concerning the efficacy of sclerosing agent tetracycline hydrochloride for treatment of thyroid cysts. However, the studies vary in patient selection and none employed a statistical method for simultaneous analysis of multiple factors that might affect the outcome of therapy. We, therefore, studied the efficacy of percutaneous instillation of tetracycline for eradication of recurrent thyroid cysts, using a multivariate analysis. Thirty-seven patients with recurrent, cytologically benign thyroid cysts (not cured after 3 aspirations) were studied. Twenty-three patients were given tetracycline instillations [100 mg/ml, range (R): 1-4 ml]. The remainder underwent only repeated needle aspiration. They were followed for 33 +/- 12 (SD) months, R: 12-58 months. Cure was achieved in 21 out of 23 cases after tetracycline instillation within 2 +/- 1.7 months (R: 1-6 months) and in 12 out of 14 cases after aspiration alone within 9.9 +/- 11.3 months (R: 1-43 months, 4-10 aspirations). Multivariate survival analysis using the Cox proportional-hazards regression model demonstrated significantly shorter time interval before cure in the group with tetracycline instillation (p = 0.001). The volume, color or duration of cysts and levothyroxine (L-T4) treatment did not appear to influence the outcome of therapy. After initial cure by tetracycline instillation, 5 cases had relapse. Three were later cured by reinstillation of tetracycline or by repeated aspirations (R: 1-3 times). Complications of tetracycline instillation included brief episode of neck pain and development of a foreign body granuloma in a single patient. In conclusion, tetracycline instillation is a quick and effective procedure for treating recurrent thyroid cysts.(ABSTRACT TRUNCATED AT 250 WORDS)