[So-called juxtaglomerular benign tumor of the kidney with renin secretion. Optical and ultrastructural study].

Benign renin secreting tumors of the kidney, of which the authors report a new case, are an uncommon cause of arterial hypertension. The lesion is unique, benign, richly vascularized and constituted by epithelioid cells similar to those seen in the normal juxta-glomerular apparatus. Noteworthy and of great diagnostic value is the massive infiltration of the tumoral tissue by mastocytes. The ultrastructural examination clearly shows the differentiation of the secretory cells from the smooth muscular fibresof the vessel walls. The other types of renin secreting tumours are briefly considered.