Intracystic tetracycline therapy for hypofunctioning cystic thyroid nodules

Hypofunctioning benign cystic thyroid nodules are a common occurrence in iodine deficient region. There are reports of resolution of recurrent thyroid cysts with tetracycline instillation. Hence we conducted a study in 20 patients with hypofunctioning benign cystic thyroid nodules to document response to intracystic instillation of tetracycline as a primary modality of treatment.

Twenty patients were thoroughly investigated for the presence of malignancy clinically, radiologically and cytologically. One milliliter of tetracycline was instilled under ultrasonographic guidance. Response to therapy was assessed clinically and ultrasonographically at one, three, six and 12 months.

Study group comprised of five male and 15 female patients with mean age 30 +/- 8 years. Initial mean volume of nodules was 15 +/- 7 ml (6 to 27 ml), which was decreased to 3 +/- 3 ml at one month, 2 +/- 3 ml at three months, and 1 +/- 2 ml at six months. Maximum number of patients (75%) responded within three months, however two patients required reaspiration and reinstallation of tetracycline. Ultrasonography revealed fibrotic scar as thick wall with internal echodensities in six patients (30%) six month after sclerotherapy. There was high rate of patient satisfaction, as cosmetically tetracycline did not leave any scar, which was unavoidable with surgery. Six patients (30%) reported mild pain after injection, and one patient developed redness at the site of injection.

Intracystic tetracycline sclerotherapy is highly effective as primary mode of treatment in hypofunctioning benign cystic thyroid nodule in selected group of patients not at high risk of malignancy.