Parathyroid adenoma in third pharyngeal pouch cyst as a rare case of primary hyperparathyroidism

Primary hyperparathyroidism-related giant parathyroid adenoma (Review)

Primary hyperparathyroidism (PHPT), an endocrine condition caused by a parathyroid adenoma (PTA) in 80-85% of the cases, has shifted in the modern era to a mildly symptomatic phenotype due to the prompt recognition of hypercalcemia and to a minimally invasive surgical approach which has a curative potential. Clinical complications of PHTH are either related to high calcium or parathyroid hormone [also parathormone (PTH)] or both, while the originating tumor typically is small, without local mass effects. A distinct entity is represented by giant PTA (GPTA) which is considered at a weight of more than 3 (3.5) grams. The present article is a review of the literature involving practical points of non-syndromic PHPT-related GPTA. Most authors agree that pre-operatory calcium and PTH are higher in GPTA vs. non-GPTA. However, the clinical presentation of PHPT may be less severe, probably due to local mass effects that bring the patient to an early medical evaluation. Age distribution, sex ratio, rate of successful pre-operatory location do not differ from non-giant PTA. Hypovitaminosis D is more frequent in PTA of higher dimensions. Post-operative hypocalcemia, but not recurrent/persistent PHPT, is expected, even hungry bone disease. A higher rate of atypia is described although the tumor is mostly benign. Unusual presentations such as cystic transformation, initial diagnosis during pregnancy or auto-infarction have been reported. The ectopic localization of PTA presented in almost 15% of all cases may also be found in GPTA. What are the exact cutoffs for defining GPTA is still an open issue.

Parathyroid Adenoma With Respiratory-Like Epithelium: Case Report of a Potential Mimic With Unknown Etiology

Parathyroid adenoma is a tumor composed of increased parenchymal tissue, often built-up by chief cells, transitional cells or oncocytic cells arranged in acinar or solid formations. Occasionally, rare histological patterns are reported, including cystic or trabecular arrangements. We present a 47 year-old male patient with primary hyperparathyroidism who underwent focused parathyroidectomy for a right inferior adenoma. Surgery was uneventful, but histologically, normal parathyroid tissue adjacent to a tumorous structure displaying a cystic growth pattern was detected. The cells lining the cyst walls appeared cylindrical and pseudo-stratified, vaguely reminiscent of a respiratory type of epithelium usually associated to branchial cleft cysts or thyroglossal cyst remnants, albeit with a tumorous appearance. The respiratory-like epithelium stained positive for parathyroid markers PTH and GATA3, thereby confirming them as parathyroid-derived. The patient was cured from surgery as he displayed normal calcium and PTH levels postoperatively, and is currently alive and well without signs of relapse 4 years after surgery. This is to our knowledge the first report of a parathyroid tumor displaying a respiratory-like epithelium. Experimentally, canine parathyroid glands can develop ciliated respiratory epithelium in response to inhalation of ozone. Our patient is a construction worker with a hypothetically increased risk of continuous ozone exposure. Although this association remains purely speculative, future investigations of this tumor phenotype could perhaps yield novel insights regarding the frequency of this histological variant, potential clinical associations, and clues regarding influencing factors.

99mTc-MIBI Uptake in a Benign Thymic Cyst

A 34-year-old man with end-stage renal failure status post rejection of a deceased donor kidney transplant presented with bone pain in the setting of elevated serum parathyroid hormone and calcium levels. A Tc-MIBI SPECT/CT was performed before planned subtotal parathyroidectomy. SPECT/CT imaging revealed a 1.9-cm anterior mediastinal lesion with radiotracer uptake on both the immediate and delayed images. Surgical pathology of the lesion showed a benign thymic cyst with no parathyroid component.