Cholangiocarcinoma Presenting as Humoral Hypercalcemia of Malignancy: A Case Report and Literature Review

Humoral hypercalcemia of malignancy (HHM) is most commonly encountered in squamous cell carcinoma (SCC) of different organs, and It is characterized by elevated parathyroid hormone-related peptide (PTHrP) levels. It may be seen as a manifestation of cholangiocarcinoma (CCC) at presentation and later in the course of the disease. However, HHM due to intrahepatic cholangiocarcinoma is a rare association and is associated with a poor prognosis. We herein report a case of hypercalcemia presenting as the first manifestation of an underlying rare variant of intrahepatic cholangiocarcinoma. Our patient is a 57-year-old male who presented to the emergency room with severe symptoms of constipation and polyuria and was admitted to the hospital for symptomatic hypercalcemia. He was found to have a hypermetabolic 15 cm liver mass, abdominal lymph nodes on imaging, which was subsequently diagnosed as adenosquamous cholangiocarcinoma by liver biopsy. This necessitated an urgent inpatient treatment with gemcitabine/cisplatin combination chemotherapy to control the aggressive nature of the malignancy. However, he deteriorated and expired after three months of his diagnosis. Adenosquamous cholangiocarcinoma is a very rare variant of a liver tumor. It develops due to squamous metaplasia of an underlying cholangiocarcinoma and usually has aggressive clinicopathological features. HMM is a life-threatening, yet unrecognized, phenomenon of cholangiocarcinoma, which represents a poor prognostic marker. Prompt recognition of this complication is important for preventing serious complications associated with hypercalcemia and to improve the quality of life of these patients.