Atypical ultrasound features of parathyroid tumours may bear a relationship to their clinical and biochemical presentation

Abstract

Objectives: To describe atypical ultrasound features of parathyroid lesions and correlate them with clinical presentation and histopathology.

Materials and methods: Retrospective review of 264 patients with primary hyperparathyroidism who underwent ultrasound imaging prior to parathyroidectomy was performed. Patients with atypical ultrasound findings (n = 26) were identified; imaging findings were correlated with clinical presentation and histopathology.

Results: Twenty-one (80 %) lesions were adenomas, two (8 %) were adenomas with cellular atypia, and three (11.5 %) were carcinomas. Seventeen (65 %) lesions showed cystic change; five (19 %) of them had >50 % cystic change. These lesions were adenomas with cystic degeneration. Cystic degeneration had significant positive correlation with the lesion size and PTH level, but cystic adenomas correlated negatively with lesion weight. Six (23 %) lesions were isoechoic and one (4 %) was hyperechoic; histology predominantly revealed haemorrhage, hyalinisation and fibrosis; one lesion showed fat deposition and another had multiple granulomas within the adenoma. Twenty (83 %) lesions had heterogeneous echotexture and showed combinations of acinar dilatation, necrosis, haemorrhage and fibrosis. Heterogeneous lesions tended to be significantly larger and heavier, and they were associated with higher PTH levels. Four (15 %) lesions had calcifications. Scintigraphy was concordant in 22 (96 %), n = 23. One scintigraphy-negative lesion was a cystic parathyroid adenoma.

Conclusion: Atypical ultrasound features of parathyroid lesions pose a diagnostic challenge. Awareness of these features would help improve lesion detection.

Teaching points: 1. Cystic change is significantly related to the size, weight and measured parathyroid hormone levels. 2. Cystic change in parathyroid tumours indicated a slightly higher risk of malignancy. 3. Heterogeneous parathyroid adenomas are larger in size and heavier, and they have higher PTH levels. 4. Awareness of atypical ultrasound features will improve preoperative clinical prediction.

Fig. 1

a Neck ultrasonography of 48-year-old male patient with primary hyperthyroidism showed a predominantly cystic right inferior parathyroid lesion with internal septations. b, c Low-power (×50, H&E stain) and high-power (×400, H&E stain) photomicrographs of the excised parathyroid lesion show a cystic tumour (*) with cells arranged in nests and an acinar pattern along the wall (arrow) with delicate fibrovascular septa lined by polygonal cells in keeping with cystic parathyroid adenoma

Fig. 2

a Neck ultrasonography of a 21-year-old female patient with primary hyperthyroidism showed haemorrhagic and cystic degeneration in the right superior parathyroid adenoma. b Low-power photomicrograph (×50, H&E stain) shows an encapsulated tumour composed of lobules of polygonal cells in keeping with parathyroid adenoma with interspersed thin-walled congested blood vessels (short arrows), areas of haemorrhage (*) and cystic degeneration

Fig. 3

a Neck ultrasonography of a 62-year-old female patient showed an isoechoic left superior parathyroid lesion. Note that it is difficult to perceive an echogenic rim around the lesion. b Low-power photomicrograph (×50, H&E stain) shows a parathyroid adenoma composed of nests of polyhedral cells with extensive fat deposition (*) and cystic haemorrhagic degeneration (short arrow)

Fig. 4

a Neck ultrasonography of a 55-year-old male patient showed a right inferior parathyroid lesion with hypoechoic and hyperechoic components. b Low-power photomicrograph (×50, H&E stain) shows a section of parathyroid adenoma with multiple discrete granulomas within (arrows). c High-power photomicrograph (×200, H&E stain) shows a well-circumscribed epithelioid granuloma surrounded by lymphocytes amidst oncocytic cells of the parathyroid adenoma

Fig. 5

a Neck ultrasonography of a 42-year-old male patient with parathyroid carcinoma showed a heterogeneous, more rounded left inferior parathyroid lesion with areas of cystic degeneration and ill-defined microlobulated margins. b Low-power photomicrograph (×50, H&E stain) shows a section of parathyroid carcinoma composed predominantly of chief cells of parathyroid with moderate pleomorphism (arrowheads), areas of haemorrhage (*), broad fibrous bands (arrow), capsular and vascular invasion

Fig. 6

a Neck ultrasonography of a 60-year-old female patient with parathyroid adenoma showed a heterogeneous, well-defined left inferior parathyroid lesion with areas of cystic degeneration and a speck of calcification. b, c Low-power photomicrographs (×25 and ×100, H&E stain) showing adenoma with cystic and haemorrhagic degeneration (*)

Fig. 7

Neck ultrasonography showed a calcified right inferior parathyroid adenoma in a 27-year-old male patient with primary hyperparathyroidism. An echogenic rim around the lesion could be seen inspite of calcification

Fig. 8

a, b Neck ultrasonography of a 31-year-old female patient with primary hyperparathyroidism shows evidence of double adenoma involving the right and left inferior parathyroid glands. The left inferior parathyroid lesion was predominantly cystic. c, d Tc-99m sestamibi scintigraphy and SPECT revealed only the right inferior parathyroid adenoma and the left inferior lesion seen on ultrasonography was not seen. e High-power photomicrograph (×100, H&E stain) of the left inferior parathyroid lesion, which was negative on scintigraphy and SPECT, shows acinar dilatation (arrowheads) and haemorrhage