This report describes the case of a 53-year-old female, who presented with a painless swelling in the left submandibular region which had gradually increased in size. Thirty years ago, this patient underwent subtotal thyroidectomy at another hospital and her thyroid function subsequently appeared normal. She presented no symptoms of hypothyroidism when she visited our hospital. A clinical diagnosis of a benign tumor arising from the submandibular gland was made with enhanced CT scan, MRI and technesium scintigraphy. The submandibular mass was surgically excised and the resected tissue revealed a well-delineated, encapsulated, solid and reddish-brown colored mass. Histological examination confirmed ectopic thyroid tissue with partial adenomatous goiter including vacuolated rich colloid in the thyroid follicles which suggested compensatory hyperplasia. Because this patient presented with post-operative hypothyroidism, we concluded that this ectopic lesion had continued to secrete thyroid hormone. Ectopic thyroid tissue should be considered in the differential diagnosis of swellings involving the submandibular area, especially if the ectopic tissue would be the only functioning thyroid tissue.
The prevalence rate of Japanese cedar pollinosis has increased since 1979. We conducted a survey of the residents of Mibu-mach, Tochigi, in 1988 and 1996 using a questionnaire to determine the prevalence rate of cedar pollinosis. Results showed its rate was 15.6% in 1988, and 25.6% in 1996. Age distribution analysis of patients with Japanese cedar pollinosis showed the highest prevalence in patients between the ages of 10 to 49 years in 1988, and between the ages of 10 to 59 years old in 1996. Within these age groups, the majority of the patients were females, but males were more prevalent than females in the age group under 19 years old. The prevalence rate of patients by age group revealed the same pattern as the age distribution of the patients. Age distribution of cedar pollinosis showed a peak in patients in their thirties both in 1988 and 1996. In conclusion, the numbers of patients with Japanese cedar pollinosis has been increasing remarkably in Mibu-mach. As climate or environmental conditions are varied in different geographical regions in Japan, further epidemiological studies in various regions of the country are required to clarify the actual prevalence rate of cedar pollinosis.
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