You will be presented with the full text of a biomedical research paper. Please write an abstract for this paper. Your response should include the abstract and no additional text.

Paper text:
a 41-year - old man with chronic renal failure and secondary hyperparathyroidism , with a serum calcium level of 11 mg / dl and a parathyroid hormone ( pth ) level of 1,520 pg / dl , underwent a two - gland total parathyroidectomy . a histopathological examination of the superior and inferior left parathyroid glands revealed hyperplastic nodular parathyroid tissue .
after the first operation , his serum calcium and pth levels decreased to 7.3 mg / dl and 211 pg / ml , respectively . hyperparathyroidism ( pth , 1,814 pg / ml ) and hypercalcemia ( calcium , 10.7 to 11.1 mg / dl ) recurred 5 years later , and multiple parathyroid nodules were detected on neck ultrasound imaging ( usg ) , which were 8 - 20 mm in diameter in and around the left thyroid lobe . no pathological lymph node was detected on neck usg . he underwent surgery again , and the left thyroid lobe with surrounding masses was resected en bloc .
the resected tissue showed nodules of varying sizes with smooth edges in the periphery of the left thyroid gland and in the skeletal muscle extending into the thyroid gland .
in one field , suture material was evident between the nodules , which was surrounded by multinucleated giant cells and indicating the previous operation ( fig .
most of the nodules were composed of uniform cells with clear to amphophilic cytoplasm and small dark nuclei , resembling chief cells ( fig .
3 ) . nuclear enlargement and a prominent nucleolus were detected in only a few cells of some nodules ( fig .
the mitotic rate was 1 - 2 in 50 high power fields ( hpf ) but was as high as 7 in 50 hpf in a limited number of fields .
no desmoplastic or inflammatory response in or around the nodules was observed , and no vascular invasion was detected .
the ki-67 proliferation index was low at 1 - 2% in most of the fields but was as high as 10% in some fields ( fig .
his postoperative serum pth level decreased to 11.5 pg / ml , and his serum calcium level ranged from 6 - 9.4 mg / dl at different times .
the patient was free of recurrence and metastatic disease at the 12 months follow - up .
parathyromatosis may arise primarily or more commonly secondarily in patients who have had prior neck surgery for secondary hyperparathyroidism.4 two theories have been suggested for the development of parathyromatosis .
the first speculates that parathyromatosis is the result of improper handling of the glands during surgical extirpation , whereas the second defines it as parathyroid gland left behind during ontogenesis that developed under physiological pressure into hyperfunctioning nests of tissue.2 additionally some authors have proposed a third theory that regards parathyromatosis as a low grade parathyroid malignancy.3 however this theory has not been accepted by further study .
parathyroid carcinoma is the main entity to be excluded clinicoradiologically and histopathologically in the differential diagnosis of parathyromatosis .
patients with parathyroid carcinoma usually have more profound hypercalcemia and metastases.1 fernandez - ranvier et al.1 found that calcium levels were significantly higher ( 14 mg / dl ) in patients with parathyroid carcinomas than those in patients with parathyromatosis . a differential diagnosis between parathyroid carcinoma and parathyromatosis can be challenging intraoperatively .
parathyroid carcinomas usually present as solitary tumors , whereas parathyromatosis present as small and numerous nodules .
in contrast , parathyromatosis is often surrounded by adherent fibrous tissue due to prior surgery , which gives the impression of a parathyroid carcinoma .
intraoperative findings can be challenging for the surgeon who tries to distinguish parathyromatosis from parathyroid carcinoma .
some authors recommend treating all such patients as if their lesions are cancerous , because occult tumors can be present in both conditions.1,5 histopathological criteria to diagnose parathyroid carcinoma should include a trabecular growth pattern , thick fibrous trabecula , mitotic figures ( > 1/10 hpf ) , capsular invasion , vascular invasion , and lymph node metastases or distant metastasis.1 in contrast to adenomas and primary parathyroid carcinomas , the real capsule is absent in the nests of the parathyroid tissue in patients with parathyromatosis . in the present case , although high mitotic rate focal areas ( 7/50 hpf ) , a trabecular growth pattern , and nuclear pleomorphism were present , these did not provide a definitive diagnosis of parathyroid carcinoma alone .
furthermore , all of these features that support the diagnosis of parathyroid carcinoma were also described in patients with parathyromatosis by fernandez - ranvier et al.1 additionally , vascular invasion , lymph node metastases , or distant metastasis , which are the reliable criteria for malignancy of endocrine neoplasms , were not present in our case .
loss of parafibromin expression , rb expression , and galectin-3 overexpression distinguish parathyroid carcinoma from other parathyroid tumors.6 as in other studies that documented galectin-3 expression in some parathyroid adenomas and hyperplastic parathyroid glands,6 - 8 galectin-3 overexpression occurred in our case .
, parathyromatosis must be considered in the differential diagnosis of a parathyroid tumor during clinical , radiological , and pathological evaluations .
it is critical for the differential diagnosis to evaluate a tumor for any features that support a parathyroid carcinoma ( infiltrative borders , lymphovascular invasion , and solitary nodules ) or for the presence of metastatic disease .
parathyromatosis , in which several nodules of hyperfunctioning parathyroid tissue form in the neck and mediastinum , is a rare cause of recurrent hyperparathyroidism . 
 however , there are some theories regarding the origin of parathyromatosis , and seeding after rupture of the parathyroid gland capsule during surgical removal of a parathyroid lesions is the most regarded one . 
 herein , we report a 41-year - old man who presented with multiple parathyroid nodules in and around the left thyroid lobe 5 years after parathyroid surgery for secondary hyperparathyroidism that was finally diagnosed as parathyromatosis . 
 we discuss the differential diagnosis of parathyromatosis from other parathyroid tumors , particularly from parathyroid carcinoma , which is important in the management of a suspected lesion .