Parathyromatosis
Authors: Tsung-Jui Wu, Ying-Tang Wang, Hung Chang, Shih-Hua Lin
Journal: Kidney International (2012)

A 45-year-old Chinese man on hemodialysis for 20 years was admitted with a 1-year history of progressive bone pain. He received left-sided video-assisted thoracoscopic surgery (VATS) to remove a mediastinal parathyroid adenoma 7 years ago. His serum intact parathyroid hormone (iPTH) concentration incrementally increased to 2500pg/ml despite aggressive medical therapy over the past year. On examination, it was observed that he was kyphotic. Laboratory studies showed total calcium 2.8mmol/l, inorganic phosphorus 2.27mmol/l, and alkaline phosphatase 732U/l. Single-photon emission CT 99mTc sestamibi scintigraphy (Figure 1) demonstrated increased uptake at the left heart border and left chest wall in the delayed phase, suggesting functioning parathyroid nodules. Chest computed tomography (Figure 2) identified three well-enhancing pleural nodules at the left cardiophrenic angle and another over the left chest wall. All four pleural parathyroid nodules were successfully removed by VATS and showed typical hyperplastic parathyroid tissue with microfollicular structure and uniform nuclei, confirming the diagnosis of parathyromatosis. Despite symptomatic improvement, a decreased but still abnormally elevated postoperative iPTH level (928pg/ml) was ascribable to the presence of orthotopic parathyroid glands and residual tiny parathyroid nests spread over the surgical bed. With the use of intravenous 1,25 (OH)2 vitamin D3 at a dose of 2μg three times weekly and calcium acetate at a dose of 4gm daily for 3 months, his serum iPTH level was still around 750pg/ml.Figure 2Chest computed tomography scan identifies three well-enhancing pleural nodules at the left cardiophrenic angle.View Large Image Figure ViewerDownload (PPT) Parathyromatosis is characterized by multiple benign-appearing and functioning parathyroid nodules and can be classified into two types.1.Palmer J.A. Brown W.A. Kerr W.H. et al.The surgical aspects of hyperparathyroidism.Arch Surg. 1975; 110: 1004-1007Crossref PubMed Scopus (67) Google Scholar The less common type 1 refers to ontogenous parathyromatosis along the embryological developmental tract. The more common type 2 refers to postsurgical parathyromatosis due to inadvertent spillage of parathyroid cells during surgical extirpation.2.Reddick R.L. Costa J.C. Marx S.J. Parathyroid hyperplasia and parathyromatosis.Lancet. 1977; 1: 549Abstract PubMed Scopus (63) Google Scholar Only 40% of parathyromatosis can be diagnosed preoperatively because of its scattered distribution and small size of individual cell nests.3.Matsuoka S. Tominaga Y. Sato T. et al.Recurrent renal hyperparathyroidism caused by parathyromatosis.World J Surg. 2007; 31: 299-305Crossref PubMed Scopus (36) Google Scholar The time from previous parathyroidectomy to the identification of parathyromatosis at reoperation ranges from 5 months to 19 years.4.Melck A.L. Carty S.E. Seethala R.R. et al.Recurrent hyperparathyroidism and forearm parathyromatosis after total parathyroidectomy.Surgery. 2010; 148: 867-873Abstract Full Text Full Text PDF PubMed Scopus (26) Google Scholar Parathyromatosis is not uncommon but under diagnosed. This case illustrates the importance of avoiding rupture of parathyroid capsule during the initial parathyroidectomy.