[A case of PTH related protein-producing large cell carcinoma of the lung]

A 41-year old woman with lung cancer was admitted to our hospital with constipation, lumbago and paraplegia. Her serum calcium level was 13.9 mg/dl. She expired on the 33rd hospital day despite vigorous fluid and supportive therapy. An autopsy was performed 1 hour later. The cause of death was rupture of the sigmoid colon and panperitonitis. To evaluate the etiology underlying the symptomatic hypercalcemia in the autopsied lung, we measured serum and tumor tissue concentrations of PTH-related protein (PTHrP) by radioimmunoassay using a specific antibody against human PTHrP (1-34), and performed immunohistochemical staining by the peroxidase-anti-peroxidase method with the same PTHrP antiserum. Northern blot analysis was also performed to detect messenger RNA in cancer tissue. All of these tests were positive for PTHrP. To the best of our knowledge, this is the first reported autopsied case demonstrated to be a PTHrP-producing large cell lung cancer by molecular biological methods.