A 48-year-old man who had been referred 9 years earlier for proteinuria. He had been treated with amlodipine, atenolol and irbesartan for 2 years. In the general study he had proteinuria 1200 mg/day, 448 red blood cells/μl in the sediment, creatinine 1.05 mg/dl and negative immunology. In the renal biopsy: 5-10 glomeruli without striking cellularity, without exudation, 2-4 glomeruli with complete sclerosis, discrete chronic lymphomonocytic infiltrates in the interstitium, without vascular involvement, without tubular atrophy; in the immunofluorescence IgM immunoglobulin deposits of focal and segmental distribution in 10 glomeruli, with + and ++ intensity in the mesangial region. He was diagnosed as focal and segmental glomerulosclerosis with the addition of ramipril 2.5-5 mg/day, observing a reduction in proteinuria to <400 mg/day. Three years ago he suffered an increase in proteinuria of 1.6 g/day, albuminuria 895 mg/day and 250 red blood cells/μl, with normoalbuminaemia and oedema. Treatment with prednisone and cyclophosphamide was tried, with a decrease in proteinuria after 7 months of treatment to 1.1 g/day, but with proximal muscle weakness that was interpreted as steroid myopathy. Prednisone was discontinued and changed to mycophenolate mofetil 1 g/day and amlodipine was withdrawn due to its possible influence on oedema, adding 12.5 mg of hydrochlorothiazide due to poor blood pressure control. After 2 months, mycophenolate was discontinued because the patient reported significant fatigue which he attributed to this drug. Cyclosporin A was then started at a dose of 150 mg/day (1.9 mg/kg/day) with good initial tolerance (levels 67.8 ng/ml). After 2 months, the patient consulted for pain in the left breast accompanied by a retroareolar nodule the size of a chestnut that was tender to the touch. Cyclosporin A was discontinued, and mammography and ultrasound were performed, finding glandular enlargement with no signs of malignancy, which was interpreted as medication-related glandular hyperplasia. Eight months later tacrolimus was introduced (initial 6 mg/day with subsequent reduction to 4-5 mg/day with levels <8 ng/ml). After 2 months the patient presented with new left breast pain, so he discontinued as he presented proteinuria <250 mg/day. At the last review 5 months later, proteinuria had risen to 650 mg/day and the glandular growth had subsided, leaving him on treatment with doxazosin, atenolol, irbesartan and ramipril.