Endocrine Abstracts

Introduction: Here, we present a case of epithelial breast cancer releasing iPTH thereby causing MAH.

Case report: A 48-year-old woman with metastatic breast cancer was consulted for hypercalcemia. Previous medical record was insignificant except for nephrolitiasis. She had a left mastectomy+left axillary lymph node dissection in another hospital. Prior to surgery no calcium levels were obtained. Pathology revealed infiltrative ductal carcinoma. Postoperatively total calcium (tCa) was 12.04 mg/dl (8.4–10.2), albumin: 4.43 g/dl, inorganic phosphate (iP): 3.21 mg/dl. Simultaneous iPTH level was 94.3 pg/ml (0.5–75) and vitamin D was 20.8 μg/l (low). After forced diuresis, tCa was 11.01, albumin: 4.4. Bone scintigraphy was negative. Primary hyperparathyroidism was suspected. Parathyroidal pathology was not detected with MIBI scintigraphy and USG. Bone mineral dansity showed osteoporosis (lomber T score: −4.2); pamidronate was begun. Prior to chemotherapy for remaining lymph nodes and liver metastasis her tCa: 9.87, albumin: 3.7. As to verify the source of iPTH, specimens were stained with PTH-antibodies. Focal positivity was observed (Figure 1). Plasma PTH-rp levels were non-detectable. Thus the diagnosis was iPTH releasing breast cancer. iPTH level was 254 on the tenth day of chemotherapy then declined to a level of 103 after 4th week.

Conclusion: In our knowledge this is the first case of iPTH releasing breast cancer. In patients without bone metastasis, release of iPTH as a reason for hypercalcemia should be kept in mind.

Figure 1 Parathyroid hormone stain focal cytoplasmic positivity was observed in the neoplastic cells (arrows) (×40) (immunohistochemistry, Human Ab-1, Clone PTH01, Labvision).

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.