Prevalence of benign and malignant thyroid nodules in patients with previous history of radiotherapy for Tinea Capitis in childhood

Increased prevalence of thyroid cancer has been noted in patients with a previous history of radiotherapy of the head and neck region in childhood. According to previous research, radiotherapy for Tinea Capitis was used for 30 years (1945-1975) in Khorasan province. This study has tried to evaluate the prevalence of benign and malignant thyroid nodules and to detect and treat affected patients earlier to prevent further complications and costs. Using mass media, we recalled all patients with history of radiotherapy for Tinea Capitis in childhood. A questionnaire was filled out for each patient and thyroid examination, thyroid scan and thyroid sonography were performed. Fine needle aspiration biopsy (FNAB) was done if a thyroid nodule larger than 1 cm was palpable. Serum TSH was measured in all patients. Also thyroid surgery was recommended for all patients with thyroid nodules of more than 1 cm. A control group were selected from a group of patients referred for non thyroidal sonography to the radiology department of Ghaem Hospital. These patients also were evaluated by clinical examination and thyroid sonography. We studied 180 patients with a mean age of 47.5 years and 127, age and sex matched controls. Thyroid nodules were palpable in 45.5% of patients and 7% of controls (p<0.01). Ultrasonography also detected thyroid nodules in 51.2% of patients and 26.1% of the controls (p<0.01). The largest mean diameter of nodules were 24.8 mm in patients and 10.8 mm in the control group (p<0.001). 73.1% of patients agreed to FNAB and 5% of them had suspicious cytology results. No suspicious or malignant results were noted in the control group. Twenty-seven patients (33.7%) were operated. Pathological results were benign in 89.9% and malignant in 11.1% of patients. This study showed that thyroid nodules and thyroid neoplasm were significantly more frequent in patients in comparison with control group, the thyroid nodules being larger in size in the patient group. Thyroid neoplasms were more frequent among younger patients with a latent period (from radiotherapy) of less than 40 years. Aggressive evaluation is recommended in these groups.