Endocrine Abstracts

Primary hyperparathyroidism is a frequent endocrine disorder but intrathyroidal parathyroid adenoma is extremely rare. Combining cervical ultrasound and MIBI scintigraphy allows localizing most parathyroid adenomas. Because intrathyroidal parathyroid adenomas mimic thyroid nodules the diagnosis can be challenging, requiring eventually the realization of a fine-needle cyto-puncture. We report here a case of an intrathyroidal parathyroid adenoma diagnosed via a combination of cervical ultrasound, cyto-puncture and MIBI scintigraphy.A 47-year old female was addressed by her GP for diarrhea and asthenia associated with a 3.3 mmol/l hypercalcemia. Biologic assessment confirmed hypercalcemia associated with hypophosphatemia and elevated PTH, confirming primary hyperparathyroidism. The patient did not present ECG modifications. Abdominal ultrasound did not find renal lithiasis and osteopenia was found on DXA. Hypercalcemia was managed with iv hydration, bisphosphonate iv perfusion and Cinacalcet oral treatment. Cervical ultrasound did not find any parathyroid adenoma but showed a 24x18x15 mm, regular, smooth border, hypoechoic EUTIRADS 4 inferior nodule in the right lobe. Scintigraphy concluded to a MIBI focal uptake behind the lower part of the right thyroid lobe. A cyto-puncture of the thyroid nodule was performed and concluded to the presence of parathyroid tissue. The patient underwent right lobectomy. Pathological analysis confirmed an intrathyroidal parathyroid adenoma.Intrathyroidal parathyroid adenoma remains a rare entity. Different case reports and studies confirm the most common ultrasound features being a solid hypoechoic nodule, smooth and regular shaped, like the adenoma presented by our patient. One feature that is extremely characteristic for the intrathyroidal parathyroid adenoma is the presence of a hyperechoic line on the ventral surface of the adenoma, feature that was not identified for our patient. Nevertheless, as these intrathyroidal adenomas mimic suspicious thyroid nodules, cyto-puncture is frequently performed before any surgery and helps confirm the diagnosis, as in our case.