Thyroid nodule growth not linked with non-nodular tissue growth

The growth of thyroid nodules was not associated with the growth of surrounding thyroid tissue, according to researchers in Italy. Based on their findings, they propose that the term “uni- or multinodular thyroid gland” be used to describe a thyroid of normal size with nodules.

“The term ‘nodular goiter’ has long been used (with several synonyms) to refer to patients with nodular lesions in the thyroid gland,” Giorgio Grani, MD, of the Dipartimento di Medicina Interna e Specialita Mediche, Universita di Roma Sapienza, and colleagues wrote. “Given its widely accepted definition — ‘a swelling in the neck due to enlargement of the thyroid gland, as caused by disease of the gland, iodine deficiency, etc.’ — one might reasonably expect the term ‘nodular goiter’ to be reserved for cases in which the volume of the gland containing the nodules is to some degree increased. The magnitude of this enlargement, however, remains poorly defined.”

The prospective, multicenter observational study enrolled 992 patients with one to four benign thyroid nodules between Jan. 1, 2006, and Jan. 31, 2008, from eight centers in Italy. The researchers conducted annual ultrasound examinations for 5 years, assessing the association between nodular and non-nodular thyroid tissue growth.

Patients had a total of 1,567 nodules at baseline. Compared with women, men had larger thyroid volumes (20.1 mL vs. 13.9 mL), and those aged 49 years or older had larger volumes than younger patients (16.1 mL vs. 13.3 mL). One-third of patients (33.3%; n = 330) met the criteria for goiter diagnosis.

Thyroid volumes did not change among patients whose nodules remained stable throughout the study period, the researchers reported (n = 839; baseline: 15 mL [95% CI, 14.5-15.6]; 5-year evaluation: 15.1 mL [95% CI, 14.5-15.7]). Thyroid volume increased among patients who demonstrated significant growth of one or more nodules (n = 153), becoming significantly greater than that of patients whose nodules remained stable (5-year evaluation: 17.4 mL [95% CI, 16-18.7]).

Unilateral nodules grew in 76 patients, Grani and colleagues reported, with nodular lobe volume exceeding contralateral lobe volume (8.6 mL [95% CI, 7.4-9.8] vs. 6.7 mL [95% CI, 6-7.4]).

Compared with the volume of unaffected lobes, which remained stable (mean value at 5 years: 6.9 mL [95% CI, 6.1-7.6), nodular lobes grew steadily over time and were significantly larger after follow-up (10.1 mL [95% CI, 8.9-11.3]).

Overall, the researchers wrote, there was almost no change in the remaining volume of affected lobes, and no change in non-nodular tissue volume in either affected or unaffected lobes throughout the study period.

“Our results suggest that, in patients of this type, the growth of thyroid nodules may be a local process, not associated with growth of the surrounding non-nodular tissue,” Grani and colleagues wrote.

The researchers also noted that thyroid size did not meet the criteria for diagnosis as a goiter in most patients.

“For that reason, we suggest that the term ‘nodular goiter’ is a misnomer in these cases,” they wrote. “While use of this term continues to be utilized in textbooks and guidelines, we feel that this condition should be distinguished from ‘uni- or multinodular goiter’ and referred to more appropriately and more informatively as a ‘uni- or multinodular thyroid gland.’” – by Andy Polhamus

Disclosures: The authors report no relevant financial disclosures.