Atypical parathyroid adenoma: clinical and anatomical pathologic features

Abstract

Background Primary hyperparathyroidism is an endocrine pathology that affects calcium metabolism. Patients with primary hyperparathyroidism have high concentrations of serum calcium or high concentrations of parathyroid hormone, or incorrect parathyroid hormone levels for serum calcium values. Primary hyperparathyroidism is due to the presence of an adenoma/single-gland disease in 80–85%. Multiple gland disease or hyperplasia accounts for 10–15% of cases of primary hyperparathyroidism. Atypical parathyroid adenoma and parathyroid carcinoma are both responsible for about 1.2–1.3% and 1% or less of primary hyperparathyroidism, respectively. Methods We performed a retrospective cohort study and enrolled 117 patients with primary hyperparathyroidism undergoing minimally invasive parathyroidectomy. Histological and immunohistochemical examination showed that 107 patients (91.5%) were diagnosed with typical adenoma (group A), while 10 patients (8.5%) were diagnosed with atypical parathyroid adenoma (group B). None of the patients were affected by parathyroid carcinoma. Results Significant statistical differences were found in histological and immunohistochemical parameters as pseudocapsular invasion (p < 0.001), bands of fibrosis (p < 0.001), pronounced trabecular growth (p < 0.001), mitotic rates of > 1/10 high-power fields (HPFs) (p < 0.001), nuclear pleomorphism (p = 0.036), thick capsule (p < 0.001), Ki-67+ > 4% (p < 0.001), galectin-3 + (p = 0.002), and protein gene product (PGP) 9.5 + (p = 0.038). Conclusions Atypical parathyroid adenoma is a tumor that has characteristics both of typical adenoma and parathyroid carcinoma. The diagnosis is reached by excluding with strict methods the presence of malignancy criteria. Atypical parathyroid adenoma compared to typical adenoma showed significant clinical, hematochemical, histological, and immunohistochemical differences. We did not find any disease relapse in the 10 patients with atypical parathyroid adenoma during 60 months of follow-up time.

Parathyroid Tumors: Molecular Signatures

“…PHPT is caused by multiple hyperplastic parathyroids in about 15% of cases, and by parathyroid tumors in approximately 85% of cases [1]. Parathyroid tumors are rare endocrine neoplasms affecting 0.1-0.3% of the general population [2], comprising slow-growing benign PTH-secreting adenomas in almost 100% of cases, atypical parathyroid adenomas in about 1.2-1.3% of cases, and extremely rare malignant carcinoma in less than 1% of cases [3]. Conversely to parathyroid adenomas (PAs), parathyroid carcinomas (PCs) show signs of local invasion and/or distant metastases and are characterized by hyperproduction of massive amounts of PTH (up to about 100-fold higher than that of adenomas) and a severe, commonly untreatable, hypercalcemia that accounts for death in a majority of cases.…”

Histological alterations following fine‐needle aspiration for parathyroid adenoma: Incidence and diagnostic problems

“…In the current study, six findings, including thick fibrous capsule, multilayered fibrous capsules, capsular pseudo‐invasion, fibrous bands, hemosiderin deposition, and tumor implantation, were considered as HAFFAP. Among them, multilayered fibrous capsules, capsular pseudo‐invasion, and fibrous bands have been described as microscopic findings of atypical adenoma or adenocarcinoma 21–23 . We recommend that the findings be excluded from pathological findings indicating atypical adenoma or parathyroid carcinoma in patients undergoing preoperative FNA.…”

A case of adrenal Cushing’s syndrome and primary hyperparathyroidism due to an atypical parathyroid adenoma

“…15 Clinically they present at the same age as patients with typical adenomas; however, the sex distribution is different and goes from a 1:1 ratio in typical adenomas to a female:male 4:1 ratio. 16 From a histological perspective, one case series found a number of differences between typical and atypical adenomas, 15,16 including increased rates of:…”