[Hypercalcemia, leukemoid reaction, and thrombocytosis as paraneoplastic presentation of transitional cell carcinoma of the kidney].
The most common etiologies of hypercalcemia are hyperparathyroidism or malignancy, most often of the lung, breast or hematological system, but rarely occur in transitional cell carcinoma. The appearance of this metabolic disorder and other paraneoplastic signs like leukemoid reaction or thrombocytosis is a potential marker for malignant behaviour and poor prognosis in advanced tumours. Simultaneous presentation of that three paraneoplastic signs have only been described in two patients with wellknown bladder carcinoma. Most paraneoplastic syndromes appear only during the late stages of malignancy when the diagnosis has long been established, but sometimes may be an early sign of the malignancy. We describe a case of a previously unknown infiltrating transitional cell carcinoma of the kidney without bony metastasis, that presented itself with hypercalcemia, hyperleukocytosis resembling a leukemoid reaction and thrombocytosis. We think recognizing the paraneoplastic syndrome is very important because it is an alarm sign of malignancy.