Hepatocellular carcinoma (HCC) is the fifth most common cancer in Korea. Diverse paraneoplastic syndromes can occur in patients with HCC, but parathyroid hormone-related peptide (PTH-rP)-induced hypercalcemia is uncommon. Hypercalcemia due to PTH or particularly PTH-rP-secreting HCC is associated with poor outcomes. We report a 71-year-old man who presented with symptoms of vague abdominal discomfort, somnolence, lethargy, nausea, vomiting, and weight loss. Imaging studies revealed a large HCC

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... ithout metastasis. The laboratory findings showed elevated serum calcium level, low intact parathyroid hormone (iPTH) level and elevated PTH-rP level. These results led to a diagnosis of a PTH-rP-secreting HCC and paraneoplastic hypercalcemia. After emergency management of the hypercalcemia, the patient underwent an extended right hemihepatectomy with cholecystectomy. One year after the surgery, he is alive with normal calcium, PTH-rP, and iPTH levels. This case demonstrates that the rare phenomenon of life-threatening hypercalcemia caused by HCC should not be overlooked. These symptoms offer a good opportunity to diagnose HCC early. Radical tumor resection makes it possible to cure patients with PTH-rP-secreting HCC. ( Korean J Gastroenterol 2015;66:122-126) greater tumor burden in patients with paraneoplastic hypercalcemia. 6 Hypercalcemia occurs abruptly and generally indicates a poor prognosis. 2,7 In one study, nearly 50% of patients with PTH-rP associated hypercalcemia died within 30 days of commencing treatment, and within three months, up to 75% of these patients died. 8 In addition, some studies reported that paraneoplastic hypercalcemia associated with HCC is often a life-threatening medical emergency 9,10 that requires prompt treatment. In Korea, a few cases of hypercalcemia associated with PTH-rP secreting HCC have been reported. 11-14 The patients were diagnosed with HCC at the advanced stage, though it was uncertain whether they had undergone any regular screening for HCC. Literature reports find that hypercalcemia was revealed with HCC simultaneously. Despite supportive care for hypercalcemia, curative treatment for HCC was not effective and all eventually expired in a few months. There are several causes of malignancy-associated hypercalcemia. Overall, approximately 80% of patients with malignancy-induced hypercalcemia display PTH-rP secretion, which most commonly occurs with squamous cell tumors. 7 The biochemical structure of PTH-rP resembles that of PTH, and both share the same PTH receptor. 15,16 Similar to PTH, PTH-rP interacts with the PTH/PTH-rP receptor that activates renal calcium reabsorption and promotes absorption of calcium from the bones. The second most common cause for hypercalcemia is the osteolytic action of skeletal metastatic lesions. Rarely, hypercalcemia may arise from vitamin-secreting tumors, particularly in patients with lymphoma, or from ectopic tumors secreting PTH. 17 The clinical features of hypercalcemia include gastrointestinal symptoms such as constipation, anorexia, nausea, varying degrees of vomiting, renal failure, as well as cardiovascular and neurological changes. With increasing severity of hypercalcemia, symptoms may gradually progress to depression, confusion, and even coma. Muscle weakness is commonly observed. The presence or absence of symptoms