CA19-9 in Benign Thyroid Cyst

Abstract

A case of a 64-year-old female with atypical mycrobacterial disease experienced tachycardia and body weight loss. Her serum CA19-9 was elevated(285.0U/ml), and both CT and ultrasonography (US) showed a tumor mass in the pancreatic body. She was operated on for partial pancreatomy. Histological examination of pancreatic sample revealed true cysts. The elevated serum CA19-9 did not change after the operation. She had goiter and laboratory data showed latent thyrotoxicosis. Thyroid US showed multinodular goiter with cystic change and a 123I scintigram revealed autonomously functioning thyroid nodules (AFTN). A fine needle aspiration biopsy of the thyroid did not show any malignant cells. Reduction of serum CA19-9 was demonstrated after every aspiration of the thyroid cyst. We supposed that the high serum level of CA19-9 was due to leakage from the thyroid cyst into the serum.To determine whether a benign thyroid cyst produces CA19-9 and causes elevation of serum concentration, we studied 15 patients with benign cysts of the thyroid. Eleven patients were diagnosed as having adenomatous goiter (AG) with cystic change and four as having Hashimoto disease (HD) with cystic change. A patient with AG showed latent thyrotoxicosis and two patients with HD showed subclinical hypothyroidism. Serum CA19-9 was within normal range in all patients. The CA19-9 content of cystic fluid was higher than the normal serum range (from70.6 to 727000.0U/ml), except in one patient who lacked the Lea and Leb antigen. In every patient of this study, the CA19-9 content of cystic fluid was higher than their individual serum CA19-9.Our results indicate that every thyroid cyst contains CA19-9, and that thyroidal CA19-9 caused an elevation of serum CA19-9 in some cases. CA19-9 is not an indicator for malignant thyroid disease.