Radiologic evidence of thymic enlargement in Graves's disease.

Abstract

Enlargement of the thymus associated with hyperthyroidism is described in endocrinology texts (2), and reference to this phenonmenon is found in the older radiological literature (1, 8). With the decline in popularity of theories considering the thymus an etiologic agent in various disease states, the recent American radiological literature has not stressed the association of thyrotoxicosis with thymic shadows seen on the chest roentgenogram. Our purpose is to document this finding, as observed in 2 patients. Case I: This 17-year-old colored female was admitted to Indiana University Medical Center on Nov. 11, 1964, with a history of thyroid enlargement over the past three years. This was accompanied by the gradual development of dyspnea on exertion, decrease in menstrual flow, and dysphagia. Physical examination disclosed mild exophthalmos, diffuse thyroid enlargement, tremor of the hands, and warm, moist skin. The protein-bound iodine was 13 mcg per 100 cc, and the cholesterol 185 mg per 100 cc. The admission chest roentgenogram (Fig. 1) demonstrated widening of the superior mediastinum, particularly on the right, with a small tongue of soft-tissue density extending into the lung field at the base of the heart. No tracheal deviation was present. On the left anterior oblique film (Fig. 2) the sail-like nature of the soft-tissue tongue, characteristic of thymus, was more apparent. A radioactive iodine scan (Fig. 3) showed diffuse enlargement of the thyroid gland with no increased radioactivity in the mediastinum. Initial treatment with antithyroid drugs resulted in considerable improvement in the patient's condition. On April 15, 1905, subtotal thyroidectomy was performed, as the patient was not considered sufficiently reliable for prolonged medical treatment. A chest roentgenogram at that time (Fig. 4) showed considerable reduction in size of the thymic shadow. Case II: This 9-year-old white male was referred to Indiana University Medical Center on Aug. 30, I966, by his school physician after a routine physical examination. For four months the child's mother had noted hyperactivity and a short attention span, and for two months increased appetite with decreased weight. The family history was pertinent in that the mother, maternal grandmother, and maternal aunt had previously been treated for Graves's disease. Physical examination showed a thin, hyperactive child with a pulse of 120 and a temperature of 100° F. Mild exophthalmos with lid lag, diffuse enlargement of the thyroid, fine tremor of the outstretched hands, and a warm, moist skin were noted. The protein-bound iodine on admission was 20 mcg per 100 cc. The chest roentgenogram demonstrated a soft-tissue mass in the region of the ascending aorta, with no associated tracheal displacement or compression (Fig. 5).