MEN-2A syndrome and pulmonary metastasis

Multiple Metastases of Parathyroid and Papillary Thyroid Carcinoma in a Female Patient Treated with Long-Term Hemodialysis

Parathyroid cancer is a rare, clinically aggressive malignancy with a prevalence of approximately 0.005% relative to all carcinoma cases and 1-5% among patients with primary hyperparathyroidism. Prognosis largely depends on the extent of the primary surgery. Non-radical surgical treatment increases the risk of local and distant metastases of the parathyroid cancer associated with limited treatment options. The combination of thyroid and parathyroid disorders has been described rather well for the general population; however, cases of parathyroid and thyroid carcinoma in the same patient are extremely rare (1 case per 3000 patients with parathyroid disorders). We present a rare clinical case of combination of parathyroid and thyroid cancers with metastases of both tumors to the neck lymph nodes in a woman with a mutation in the MEN1 gene (NM_130799.2): c.658T > C p.Trp220Arg (W220R), who has been exposed to radiation for 20 years before diagnosis of thyroid cancer and received renal replacement therapy with long-term hemodialysis before the diagnosis of parathyroid cancer. The patient underwent several surgeries because of metastases of the parathyroid cancer in the neck lymph nodes. Surgeons used intraoperative navigation methods (single-channel gamma detection probe, Gamma Probe 2, and fluorescence angiography with indocyanine green (ICG)) to clarify the volume of surgery. Currently, the patient is still in laboratory remission, despite the structural recurrence of tumors.

[Casuistic cases of parathyroid carcinoma with a verified mutation in the MEN1 gene]

Parathyroid cancer (PTC) is usually sporadic; however, it could be presented as a component of hereditary syndromes. The prevalence of PTC among patients with primary hyperparathyroidism (PHPT) is about 1% cases. The lack of reliable preoperative predictors significantly complicates the diagnosis of PTC. The clinical course is non-specific and in most cases is determined by severe hypercalcemia. The final diagnosis can only be made on the basis of invasive histopathologic features, while an analysis immunohistochemical (IHC) one can be used only as an additional method. Given the rarity the diagnosis of MEN1-related PTC a challenge. We present two clinical cases of patients with PTC and a verified heterozygous mutation in the MEN1 gene. The described cases demonstrate the complexity of morphological diagnosis for PTC, the heterogeneity of clinical manifestations in patients with the MEN1 mutation, as well as the need for timely screening to identify other components of MEN1 syndrome and mutations of the MEN1 gene among first-line relatives.

Incidence, survival time, and surgical treatment of parathyroid carcinomas in dogs: 100 cases (2010-2019)

OBJECTIVE

To evaluate outcomes of dogs with parathyroid carcinoma (PTC) treated by surgical excision and to describe the incidence of postoperative hypocalcemia, degree of hypocalcemia, duration of hospitalization, duration of calcium supplementation, and survival time.

ANIMALS

100 client-owned dogs with PTC admitted to academic, referral veterinary institutions.

PROCEDURES

In a retrospective multi-institutional study, medical records of dogs undergoing surgical excision of PTC between 2010 to 2019 were reviewed. Signalment, relevant medical history, clinical signs, clinicopathologic testing, imaging, surgical findings, intraoperative complications, histologic examination, and survival time were recorded.

RESULTS

100 dogs with PTC were included, and 96 dogs had clinical or incidental hypercalcemia. Common clinical signs included polyuria (44%), polydipsia (43%), hind limb paresis (22%), lethargy (21%), and hyporexia (20%). Cervical ultrasonography detected a parathyroid nodule in 91 of 91 dogs, with a single nodule in 70.3% (64/91), 2 nodules in 25.3% (23/91), and ≥ 3 nodules in 4 (4/91)% of dogs. Hypercalcemia resolved in 89 of 96 dogs within 7 days after surgery. Thirty-four percent of dogs developed hypocalcemia, on the basis of individual analyzer ranges, within 1 week after surgery. One dog had metastatic PTC to the prescapular lymph node, and 3 dogs were euthanized for refractory postoperative hypocalcemia. Estimated 1-, 2-, and 3-year survival rates were 84%, 65%, and 51% respectively, with a median survival time of 2 years.

CONCLUSIONS AND CLINICAL RELEVANCE

Excision of PTC results in resolution of hypercalcemia and excellent long-term tumor control. Surgical excision of PTC is recommended because of resolution of hypercalcemia and a good long-term prognosis. Future prospective studies and long-term follow-up are needed to further assess primary tumor recurrence, metastasis, and incidence of postoperative hypocalcemia.

Parathyroid carcinoma

Parathyroid carcinoma (PC) is a rare disease with an indolent behavior due to the low malignant potential. The etiology is unknown. Somatic mutations of CDC73 gene, the same gene involved in the hyperparathyroidism-jaw tumor syndrome, can be identified in up to 70% of patients with PC and in one-third of cases the mutations are germline. Therefore, in patients who carry germline CDC73 gene mutations, its finding permits to identify the carriers among relatives and sometimes to early detect a parathyroid lesion in such subjects. The diagnosis of PC is commonly made after surgery, however there are some clinical/biochemical features that should raise the suspicion of PC, namely markedly elevated serum calcium and PTH levels, a large parathyroid lesion with suspected ultrasonographic features of malignancy, the damages of kidney and bones. The best chance of cure is the complete surgical resection with the en-bloc excision at the first operation, however several recurrences are often observed during the follow-up. Since PC is an indolent tumor with long-lasting survival and the death is due to complications of untreatable hypercalcemia, multiple surgical interventions with debulking of tumoral tissues along with medical treatment for reducing hypercalcemia are often needed. Patients with PC should be followed up along their lifetime.

Molecular genetics of syndromic and non-syndromic forms of parathyroid carcinoma

Parathyroid carcinoma (PC) may occur as part of a complex hereditary syndrome or an isolated (i.e., non-syndromic) non-hereditary (i.e., sporadic) endocrinopathy. Studies of hereditary and syndromic forms of PC, which include the hyperparathyroidism-jaw tumor syndrome (HPT-JT), multiple endocrine neoplasia types 1 and 2 (MEN1 and MEN2), and familial isolated primary hyperparathyroidism (FIHP), have revealed some genetic mechanisms underlying PC. Thus, cell division cycle 73 (CDC73) germline mutations cause HPT-JT, and CDC73 mutations occur in 70% of sporadic PC, but in only ∼2% of parathyroid adenomas. Moreover, CDC73 germline mutations occur in 20%-40% of patients with sporadic PC and may reveal unrecognized HPT-JT. This indicates that CDC73 mutations are major driver mutations in the etiology of PCs. However, there is no genotype-phenotype correlation and some CDC73 mutations (e.g., c.679_680insAG) have been reported in patients with sporadic PC, HPT-JT, or FIHP. Other genes involved in sporadic PC include germline MEN1 and rearranged during transfection (RET) mutations and somatic alterations of the retinoblastoma 1 (RB1) and tumor protein P53 (TP53) genes, as well as epigenetic modifications including DNA methylation and histone modifications, and microRNA misregulation. This review summarizes the genetics and epigenetics of the familial syndromic and non-syndromic (sporadic) forms of PC.

Nonfunctional Metastatic Parathyroid Carcinoma in the Setting of Multiple Endocrine Neoplasia Type 2A Syndrome

Parathyroid carcinoma is a very rare malignancy. It has been associated with hyperparathyroidism-jaw tumour syndrome, familial isolated primary hyperparathyroidism, and multiple endocrine neoplasia type 1 (MEN-1) and 2A (MEN-2A) syndromes. We report a 54-year-old man with a MEN-2A which presents with a nonfunctional metastatic parathyroid carcinoma and a pheochromocytoma in the absence of medullary thyroid carcinoma. Only a few cases of parathyroid carcinoma have been reported in the literature associated with this syndrome.