HYPERCALCEMIA ASSOCIATED WITH PARATHYROID HORMONE-RELATED PROTEIN PRODUCED BY B-CELL TYPE PRIMARY MALIGNANT-LYMPHOMA OF THE KIDNEY

A patient with primary non-Hodgkin's (B-cell type) lymphoma of the kid ney developed hypercalcemia at the terminal stage of the disease. Alth ough the plasma parathyroid hormone level was low, urinary cyclic AMP excretion was elevated. Serum osteocalcin (BGP) was suppressed and the plasma level of 1,25(OH)(2)D was within the normal range. Serum conce ntrations of PTH-related protein (PTHrP)- like immunoreactivity (PRP-L I) were elevated and the tissue concentration of PRP-LI in the postmor tem lymph node showed high level along with elevated serum PRP-LI, fur thermore the production of PTHrP by tl-le tumor was demonstrated by im munohistochemistry and Northern blotting analysis. These findings indi cate that the hypercalcemia of the patient was caused by the PTHrP-pro ducing B-cell lymphoma. Hypercalcemia was restored to normocalcemia by bisphosphonare treatment. Our case will add further information on hu moral hypercalcemia in B-cell lymphoma, which rarely has been demonst rated to produce PTHrP.