Skull metastasis of thyroid carcinoma. Study of 12 cases.

Over the past 33 years the authors have treated 12 cases of skull metastasis from thyroid carcinoma, accounting for 2.5% of a total of 473 cases of thyroid cancer. A study of these 12 cases revealed the following characteristics. The mean age of the patients was 60.4 years and the predominant incidence was in the seventh decade of life. The incidence of skull metastasis from thyroid cancer was higher among women than among men. The primary sign was a soft hemispheric tumor resting on the skull. The tumors were rich in vascularity with osteolytic changes in the skull. The average period from diagnosis of the thyroid tumor until thyroidectomy was 14.3 years, and until discovery of the skull metastasis was 23.3 years. The clinical course was thus very long. The most frequent histopathological presentation was follicular adenocarcinoma. Such lesions were morphologically well differentiated, with little pleomorphism and atypism, but detailed examination showed infiltration into the vascular lumen or capsule. The mean survival time in these patients was 4.5 years from the time of diagnosis. The prognosis in this lesion was relatively poor, considering its long clinical course.