Percutaneous tetracycline instillation for sclerosis of recurrent thyroid cysts.

Of 770 hypofunctioning thyroid nodules subjected to needle biopsy since 1977, the fluid of 172 cysts (22%) was aspirated. The fluid, cytologically examined, showed no evidence of carcinoma except in three instances: papillary carcinomas that were subsequently treated surgically. Of the cystic lesions, 19 (11%) recurred and were treated by reaspiration and the instillation of tetracycline hydrochloride into the cyst cavity. In all but one instance this resulted in obliteration of the cysts (95%). This is a considerably higher rate of success than that reported from aspiration alone (40% to 85%). The follow-up period ranged from 1 to 42 months, with no recurrence or subsequent development of a thyroid nodule in these patients. The one recurrent cyst was reaspirated and reinstilled a second time, which resulted in great reduction in size. Not considered for this procedure were patients in whom the cytologic condition of the fluid was abnormal or indicative of a malignancy. Also excluded were those in whom there was incomplete decompression of the cyst, manifested by a persistent nodule. No patients had a history of head or neck irradiation or cervical lymphadenopathy, both contraindications for this procedure. No patients had grossly bloody aspirates. Recurrence of thyroid cysts after aspiration was not thought to be, in itself, a criterion for surgical selection. The effective use of tetracycline hydrochloride as a sclerosing agent in the treatment of malignant pleural effusions is well documented. Its action in producing symphysis is thought to be related to its low pH (2.0). This procedure is safe, simple, cost effective, and well tolerated by patients. It obviates the need for excision in patients who fulfill the aforementioned criteria.