Endocrine Pathology Case Studies


CASE 2: Hyperparathyroidism with Parathyroid Adenoma


Clinical History:

A 30-year-old healthy active man goes to his physician for a routine check-up for employment at a new job. There are no abnormal physical examination findings. Laboratory studies show a serum calcium of 11.5 mg/dl (normal 8.6 to 10.7) with a serum albumin of 5.1 g/dL and a serum phosphorus of 2.0 mg/dl (normal 2.4 to 4.1), creatinine 1.1 mg/dL, and glucose 77 mg/dL. His Hgb is 14.4 g/dL, Hct 43.4%, MCV 89 fL, platelet count 239,000/microliter, and WBC count 6760/microliter. A chest x-ray is unremarkable. He is taking no medications or vitamins. He denies abdominal pain or bone pain.
What additional laboratory test would you order to confirm the diagnosis? A parathormone assay should be ordered. In this case, it was 1.8 ng/ml (normal 0.5 to 1.8).
A Tc99m Sestamibi scan was performed and showed a solitary region of uptake corresponding to a left lower pole parathyroid gland.
He is taken to surgery, and a single nodule is identified lateral to the thyroid and removed after frozen section consultation with the pathologist. The remaining parathyroid glands are identified and are not enlarged.
  1. What is the diagnosis in this case?

    2. This is a parathyroid adenoma. There is a rim of normal parathyroid tissue with fat seen around the adenoma in image 2.2, and the cells seen in image 2.3 have the appearance of chief cells. What is the diagnosis in image 2.4? This is parathyroid hyperplasia, since all four glands are enlarged (half of the gland seen at the lower left was re-implanted). Both of these conditions produce primary hyperparathyroidism, which is diagnosed when there is both elevated calcium and elevated parathormone. Don't forget that the lower parathyroid glands and the thymus are derived from a similar embryologic origin (third branchial pouch) so that parathyroid tissue may be found down in the mediastinum!

  2. How are these lesions most often detected?

    3. Nowadays, with routine biochemical screening tests, they are most often picked up because of a high serum calcium. About a third of patients, like this man, are asymptomatic. However, most cases of hypercalcemia are not due to hyperparathyroidism; about a third of cases are due to hyperparathyroidism, a third to malignancies, and a third to miscellaneous causes).

  3. What are the consequences if untreated?

    4. Clinical symptoms of hypercalcemia may include weakness and fatigue, depression, psychosis, coma, renal stones, osteitis fibrosa cystica, peptic ulcers, pancreatitis, hypertension, cholelithiasis, and soft tissue calcification.

  4. Why was it necessary for the surgeon to identify all four glands?

    5. Both parathyroid hyperplasia, or a second adenoma, must be excluded.

  5. What are the criteria for malignancy in parathyroid tumors?

    6. A parathyroid carcinoma is less common than adenoma but is diagnosed by metastases, invasion of contiguous structures (making the tumor adherent to surrounding tissues at surgery), tumor thrombi in veins, fibrous bands, mitotic figures, and a very high serum calcium.