NonMEN Familial Hyperparathyroidism and Parathyroid Cancer

Both parathyroid cancer and NMFH are rare parathyroid disorders. The association of these rare conditions suggests a common cause. Until 2002, 29 patients with NMFH and parathyroid cancer in 22 families were reported.16,21,23,27*33,35,43 Sixteen of these families have NMFH-JT or FIH-JT, and about one fourth of reported NMFH families have one or two affected members suffering from parathyroid cancer. Endocrinologists and surgeons should be aware of this association for proper management of these patients.

Clinical Features

Reviews of 15 cases of NMFH and cancer were reported before 1993. The mean age of the patients with NMFH and parathyroid cancer at initial diagnosis was 30 years (range, 14 to 43 years), which is considerably younger than that of other patients with parathyroid cancer (50 years) (Table 55-3).41 Seven males and eight females were affected. The clinical manifestations among these patients were similar to those of other patients with parathyroid cancer. The mean serum calcium level was 16.1 mg/dL, and one third presented in hypercalcemic crisis. Sixty-one percent of these patients had severe osteitis fibrosa cystica and 30% had nephrolithiasis. Twenty-three percent presented with a palpable neck mass.

Pathogenesis

In some patients with NMFH and parathyroid cancer, one or more of the other parathyroid glands were also abnormal.21,35,43 This occurrence raises the possibility of the transformation of benign parathyroid neoplasms to parathyroid cancer similar to the transformation of C-cell hyperplasia to medullary thyroid carcinoma. In most studies, however, there is no evidence of transformation proceeding from hyperplastic glands to parathyroid cancer because 60% of these patients have only parathyroid cancer.36,37,39"42

TABLE 55-3. Clinical Features of 15 Patients

with Non-MEN Familial Hyperparathyroidism

and Parathyroid Cancer

Male/female ratio

7:8

Mean age

30 yr

Mean serum calcium level

16.1 ± 1.0 mg/dL

Gone disease

61%

Renal stone

30%

Hypercalcemia crisis

30%

Neck palpable mass

23%

MEN = multiple endocrine neoplasia.

NMFH-JT or FIH-JT is known to be linked to chromosome Iq25-q31 abnormalities. NMFH and parathyroid cancer arising without tumors of the upper and lower jawbones have never, to our knowledge, been identified with a specific genetic mutation,33 although three somatic chromosome abnormalities (reciprocal translocation between chromosomes 3 and 4, trisomy 7, and a pericentric inversion in chromosome 9) were also noted in cultured parathyroid cells from one patient with NMFH and parathyroid cancer.37

At operation, when one encounters a parathyroid tumor that is hard, grayish white, lobulated, or invasive, parathyroid cancer must be suspected. An en bloc excision of the parathyroid neoplasm and ipsilateral thyroid lobe or other adherent tissues is recommended (especially for patients with profound hypercalcemia). For such patients with recurrent or metastatic disease, an aggressive surgical approach, even when palliative, is recommended to palliate symptoms of HPT41 and to decrease the metabolic problems. Persistent or recurrent hypercalcemia occurred in about 40% of the patients with NMFH and parathyroid cancer, a rate similar to that reported for patients with sporadic parathyroid carcinoma.

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