[Hypercalcemia associated with hyperleukocytosis, a new paraneoplastic syndrome].

BACKGROUND: The association of hypercalcemia and leukocytosis constitutes a novel paraneoplastic syndrome rarely reported in the course of head and neck and lung squamous cell carcinoma. We report 7 new cases. CASE REPORTS: In 5 cases the diagnosis was well-differentiated squamous cell carcinoma, in 1 differentiated non-small-cell carcinoma and in 1 adenocarcinoma of unknown origin. There was no argument favoring hyperparathyroidism in any of the cases. Microbiology tests were negative and large spectrum antibiotics were unsuccessful, eliminating an associated infection as cause of the leukocytosis. DISCUSSION: This association probably involves the secretion of hematopoietic growth factors such as G-CSF or GM-CSF by the tumor, acting simultaneously on osteoclasts and granulomonocytic cells which have common precursers.