Endocrine Abstracts

Introduction: Ectopic PTH secretion is rare, to our knowledge, with only 27 cases reported in the literature and 3, ( a tonsil, a lung and a penile) due to squamous cell carcinoma .In the few cases reported to date it appears to be more common in males and in those over the age of 60. The management of the hypercalcemia in this setting is complicated. We are aware of 2 other case reports in which cinacalcet was used in this context, but as in our case, unsuccessfully.

Case report: A 75 year old man, with a previous history of a stage IVA(T4a N0M0) squamous cell carcinoma of the floor of the mouth that was in progression 2 months prior to being admitted, presenting a 1 week history of malaise due to severe hypercalcemia( previous levels were normal ) The patient did not have evidence of bony metastatic disease on imaging studies. Further laboratory evaluation revealed PTHrP of < 1.1 pmol/l ( 0–1.5), increase PTH level of 404 pg/ml (10–65), and 25-OH vitamin D level of 16 ng/ml ( 30–80), 1.25 Dihidroxi vitamin D 37 pg/ml (25–66), consistent with PTH dependent hypercalcemia Ultrasonography, Technetium 99 scanning, and CT examination of the neck and chest failed to identify adenoma, hyperplasia or an ectopic parathyroid gland. We therefore considered the possibility of an ectopic source of PTH. Immunohistochemical staining for PTH in cytology was attempted in our patient, however this was negative .This result may have been due to the quality of the sample .A biopsy of the primary mass was not performed as the procedure was not in the best interest of the patient due to the patient’s rapidly worsening condition. Inspite of therapy with fluids, cinacalcet, zolendronic acid, the patient remained hypercalcemic, observing an increase in PTH as an ”escape phenomenon” . The patient died a month after his diagnosis.

Conclusion: It is important to look for alternative etiologies in cases of hypercalcemia in the setting of malignancy including both PTHrp related and paraneoplastic ectopic secretion of PTH.

The management of the hypercalcemia in this setting is complicated and often times associated to poor prognosis. A better prognosis and management of hypercalcemia in this context, is related to the treatment of the malignancy, with surgery or chemotherapy. More studies are needed to determine whether there is a role for calcimimetics in this context.