Adenosquamous pancreatic cancer producing parathyroid hormone-related protein

An autopsy case of adenosquamous pancreatic cancer in a 61-year-old male patient with an elevated serum level of parathyroid hormone-related protein (PTH-rP) is reported. He was admitted to our hospital with a 1-month-long history of abdominal discomfort and progressive abdominal fullness. A computed tomography (CT) scan of the abdomen showed a retroperitoneal mass, approximately 10 cm in diameter, involving the pancreas, with round enhancement on contrast examination. Histological examination of a specimen taken by CT-guided needle biopsy suggested squamous cell carcinoma or transitional cell carcinoma. Laboratory data on admission revealed a high serum calcium level and high PTH-rP level. The calcium level initially responded to intravenous hydration, furosemide, calcitonin, and bisphosphonates, decreasing from 15.0 to 9.0 mg/dl. However, the hypercalcemia recurred after 10 days. The patient developed carcinomatous peritonitis and acute renal failure, and died on the 25th hospital day. Autopsy revealed a mass in the pancreatic body to tail, invading the retroperitoneum, with progressive carcinomatous peritonitis. Histological examination of the mass revealed infiltrating carcinoma, showing squamous differentiation with focal intracytoplasmic lumina formation, consistent with pancreatic adenosquamous carcinoma. Immunohistological examination showed positive staining for PTH-rP. Adenosquamous carcinoma of the pancreas is relatively rare; only a few cases associated with hypercalcemia and for which PTH-rP has been identified as a causative factor have been reported. This is the first case in which immunohistochemistry proved localized PTH-rP in adenosquamous pancreatic cancer cells, associated with persistent hypercalcemia.