Paraneoplastic hypercalcemia in a patient with adenosquamous cancer of thecolon

Hypercalcemia is a well-known manifestation of paraneoplastic syndromes ass ociated with a variety of malignancies. However, colon cancer has only rare ly been associated with hypercalcemia of malignancy. We present the case of a patient with recurrent adenosquamous carcinoma of the ascending colon fo und to have hypercalcemia. The patient is a 76-year-old white woman who ini tially presented with colon cancer in the cecum and underwent a right hemic olectomy. All lymph nodes and surgical margins were free of tumor. Patholog ical examination at that time revealed adenosquamous carcinoma of the colon . Eight months later she complained of dizziness, anorexia, and constipatio n and was found to have a calcium level of 13.6 mg/dL. CT scan revealed a m ass measuring 10.5 to 12.7 cm in the right hepatic lobe, and a bone scan wa s normal. Her intact parathyroid hormone (PTH) level was 6 pg/mL (normal 12 -72) and her PTH-related protein (PTHrP) level was 25.7 pmol/L (normal <1.3 ). She then underwent a hepatic resection. The serum PTH, calcium, and PTHr P levels normalized after resection. Hypercalcemia of malignancy in colon c ancer is rare and has an association with adenosquamous histology. The hype rcalcemia is attributed to PTHrP, and here we demonstrate this in the serum and tumor specimens. The effects of PTHrP are shown to be short-lived post operatively. We find only 14 other cases in the literature of hypercalcemia related to a colonic neoplasm, and this is the only patient reported to be surviving. The diagnosis of a paraneoplastic syndrome mediated via PTHrP s hould be considered when hypercalcemia is encountered in the setting of met astatic colon carcinoma.