Primary hyperparathyroidism due to a cystic parathyroid adenoma in a cat

Abstract

A 15-year-old neutered female domestic shorthair cat was presented for weight loss, polydipsia/polyuria, and lethargy. A large fluctuant mass was palpated in the ventral right cervical region. Biochemistry results were consistent with primary hyperparathyroidism. Parathyroid hormone level in the fluid was higher to that observed in the plasma, consistent with a cystic parathyroid lesion. Right parathyroidectomy and thyroidectomy were performed without complications. Ionized calcium normalized within a few hours. Histopathology yielded a diagnosis of cystic parathyroid adenoma. Follow-up showed complete recovery of clinical signs and normalization of ionized calcium. This case shows an uncommon presentation of feline primary hyperparathyroidism secondary to a cystic parathyroid adenoma and is, to our knowledge, the first case presented with a large palpable mass in which parathyroid hormone concentration was measured. This report highlights the value of selective hormonal analyses of the cystic fluid to confirm the origin of the cystic lesion pre-operatively.

Primary hyperparathyroidism caused by bilateral parathyroid cystic carcinoma in a cat

“…Preoperative distinction between a thyroid and a parathyroid lesion can be challenging even with ultrasonography, CT and FNA, 3 , 6 – 8 which was also the case in this cat. In many of the previously reported cases, exploratory surgery of the ventral neck had been performed in order to confirm the diagnosis.…”

“…[1][2][3][4][5][6][7] It is caused by overproduction of PTH due to parathyroid gland hyperplasia or an autonomously functioning parathyroid adenoma, cystadenoma or carcinoma, with adenoma being the most common and carcinoma the rarest form. 1,[3][4][5][6][8][9][10] To our knowledge, this is the first case report of a bilateral parathyroid cystic carcinoma in a cat.…”

“…1,2,6,11 However, intraoperative identification of all hyper-functional tissue can be difficult, especially in the presence of non-functional thyroid and parathyroid nodules. 8,12 Indeed, in a recent study, several cats needed a second operation owing to persistent hypercalcaemia. 1 Many of the functional parathyroid masses reported have been cystic, 5,8,9 and the cysts of functional parathyroid masses typically contain a much higher concentration of PTH compared with that of serum.…”

“…8,12 Indeed, in a recent study, several cats needed a second operation owing to persistent hypercalcaemia. 1 Many of the functional parathyroid masses reported have been cystic, 5,8,9 and the cysts of functional parathyroid masses typically contain a much higher concentration of PTH compared with that of serum. 3,8,9 Measuring PTH concentration in cystic fluid preoperatively is recommended to confirm the hormonal activity of the mass.…”

“… 1 , 4 , 5 It is further supported by identifying a mass in the ventral cervical region by palpation, ultrasonography or CT, 1 , 5 and ultimately confirmed by histopathology. 1 – 3 , 5 , 8 Ultrasonography can also aid in evaluating regional lymph nodes, ruling out other causes for the non-specific clinical signs, and detecting changes secondary to the hypercalcaemia such as soft tissue mineralisation, urinary calculi and renal degeneration. 1 , 2 In this case, the laboratory results and the diagnostic imaging findings were consistent with primary hyperparathyroidism, with no evidence of metastasis or significant soft tissue mineralisation.…”