Papillary thyroid cancer associated with syndrome of inappropriate antidiuresis: a case report

Abstract

Introduction: The syndrome of inappropriate antidiuresis is the most common cause of euvolemic hypo-osmolality. This syndrome is associated with a wide variety of diseases. However, its most frequent causes are related to malignancies, especially lung cancer. In this case report, we describe an unknown association of the syndrome of inappropriate antidiuresis with papillary thyroid cancer.

Case presentation: We present the case of a 71-year-old Caucasian, German woman with marked hyponatremia and neurological symptoms. After a detailed clinical investigation, the common causes of syndrome of inappropriate antidiuresis and other malignancies were ruled out. A thyroid nodule was detected by ultrasound and magnetic resonance imaging. Although fine needle aspiration cytology showed negative results, our patient underwent surgery. Papillary thyroid cancer was later diagnosed. After total thyroidectomy, a complete remission of the clinical symptoms occurred and our patient subsequently had iodine-131 radioactive therapy. Hyponatremia was no longer observed during the follow-up investigations.

Conclusion: This is the first reported case of paraneoplastic syndrome of inappropriate antidiuresis caused by papillary thyroid carcinoma. Since its symptoms occurred before the development of local symptoms, total thyroidectomy may provide a timely and efficient treatment for the underlying malignancy.

Figure 1

MRI scan of the neck. (A) T2 blade sequence. (B) T2 blade sequence with contrast enhancement. The thyroid nodule of the right lobe is indicated by a white arrow. (Images were provided by the Institute of Radiology, University of Regensburg).

Figure 2

Histological slides of the resected differentiated papillary thyroid cancer. (A) Papillary thyroid cancer. (B) Papillary thyroid cancer, high magnification, illustrating the papillary structures.