Endocrine Abstracts

Introduction: Ectopic parathyroid tissue is a rare cause of primary hyperparathyroidism (PHPT). Intrathyroid location has been reported in 18–33% of cases.

Case report: A 67-year-old Caucasian female was admitted for evaluation of multi-nodular goiter and normocalcaemic PHPT. The patient was asymptomatic; her medical history was remarkable for hypertension, dyslipidaemia, and albuminuria. Her family history has positive for albuminuria.

Physical examination showed diffuse goiter and a palpable nodule at the left thyroid lobe. Initial laboratory assessment showed: corrected total serum calcium: 9.4 mg/dl (normal: 8.8–10.6), serum phosphorus: 3.1 mg/dl (normal: 2.5–4.5), PTH: 86 pg/ml (normal: 10–53), 25-hydroxyvitamin-D: 38 ng/ml (normal: >30), TSH: 0.59 mIU/l (normal: 0.4–4), calcitonin: 1 pg/ml (normal: <10), estimated glomerular filtration rate: 65 ml/min per 1.73 m², 24 h-urinary calcium: 164 mg/24 h (normal: 0–250).

Neck ultrasound revealed a 10×8.6 mm bean-shaped hypoechoic lesion, two hypoechoic nodules <7 mm and one with microcalcifications (7×5.2 mm) in the right lobe. A 21×18 mm isoechoic nodule (‘hot’ on thyroid scan), two hypoechoic nodules (10 and 7 mm) and one with microcalcifications (8×5 mm) were found in the left lobe. No abnormal lymph nodes were observed. Renal ultrasound was normal.

Ultrasound-guided fine-needle-aspiration-biopsy (FNA-b) was performed in the nodules with microcalcifications and the bean-shaped one. PTH was measured in the aspirate of the latter. Cytopathology showed ‘atypia of undetermined significance’ (BETHESDA III), while PTH-washout concentrations were 1900 pg/ml.

The patient underwent total thyroidectomy, showing bilateral multifocal papillary thyroid carcinoma (PTC) with microscopic invasion of perithyroidal tissue, two right parathyroid glands with hyperplasia (one intrathyroid) and one normal left gland.

Postoperatively, PTH levels did not normalize, calcium remained normal and the patient was referred to adjacent radioiodine ablation.

Conclusions: This is the second case of intrathyroid parathyroid gland co-existing with PTC. Parathyroid FNA-b with PTH washout may be a useful diagnostic tool in such cases.