Kidney mass and osteolytic lesion: is it always malignancy?

A 43-year-old man was referred to us on March 2005, for further evaluation of a ‘presumed renal tumour’ with two osteolytic lesions located in the right 11th rib and in the left 12th rib. On October 2004, this patient was seen in an emergency service with a tender and slightly erythematous protuberance located in the lower and posterior right hemithorax, measuring approximately 12 cm in its largest diameter. He did not experience fever or weight loss, and an abdominal ultrasonography reported a cystic mass in the left kidney. In the following weeks, there was a gradual regression of the protuberance, but in December 2004, a new and comparable tender protuberance developed in his left hemithorax, at the same level. Again, he had no evidence of fever. An abdominal CT scan disclosed a hypodense mass located in the lower half of the left kidney, with a more hypodense area near the lower kidney pole, leading to a suggestion of an ‘inflammatory/necrotic lesion’ (Figure 1). The physical examination on admission showed a healthy looking individual with a blood pressure of 120/70mmHg, pulse rate of 102/min and an axillary temperature of 37.48C. Lungs and heart were normal on auscultation. A well-defined erythematous protuberance was seen in the lower and posterior left hemithorax, with moderate pain on palpation. Laboratory tests provided the following results: normal urinalysis without proteinuria, serum creatinine 0.9mg/dl and normal serum electrolytes. The haemogram indicated haemoglobin 13.1 g/dl, haematocrit 37.3% and white blood cell count 10 330/ml. VDRL was positive (1:256) with a reagent FTA-abs test, and Anti-HIV, HBsAg and anti-HCV were negative. The chest X-ray showed only the osteolytic lesions as above described. Fine needle ultrasonography-guided biopsies of both the left costal lesion and kidney mass were performed.