Renal Amyloidosis Secondary to Acne Conglobata

A 62-year-old white man had, since the age of 20, acne conglobata affecting predominantly the back, buttocks, and abdomen (Fig. 1). One year before hospitalization, proteinuria was detected. Five months later, proteinuria was persistent and renal failure had appeared. Two months before admission, surgical excision of chronic suppurative skin lesions of the buttocks was performed. One month before admission, serum creatinine was 5.9 mg/dl and the hematocrit 25.6%. The patient was hospitalized because of diarrhea, vomiting, drowsiness and progressive dispnea of 3 week's duration, with oliguria in the last 48 hours. On examination, the patient appeared to be chronically ill, with axilar temperature of 36.5C, the blood pressure was 120/60 mmHg, the pulse rate, 100/min. He was stuporous and asterixis was evident. Cutaneous lesions of acne conglobata were present on the back, buttocks, and abdomen. Laboratory studies showed a hematocrit of 21.2% and a leukocyte count of 16,200/fi\ with 85% neutrophils, 4% lymphocytes, and 11 % monocytes. The blood urea nitrogen level was 115 mg/dl, and the creatinine level was 12.5 mg/dl. The calcium level was 6.3 mg/dl; the phosphorus level, 8.5 mg/dl; and uric acid, 2.7 mg/dl. The total serum protein level was 6.1 g/l (albumin 2.13 g/l, globulins 3.97 g/l). No serum M-component was present. Serum glucose, sodium, potassium, and bilirubin were within normal limits. Urine sediment contained 20 leukocytes per high-powered field. The 24-hour proteinuria ranged between 7 and 15 g. There was no evidence of Bence-Jones protein. Coomb's test, rheumatoid factor, antinuclear antibodies, serum complement and serologics tests for syphilis were negative or normal. X-rays of the chest and abdomen were normal. A skin biopsy showed inflammatory infiltrate around the follicles with hyperkeratinization of the neck of the follicles with formation of abscesses in the dermis. Amiloid stains (Congo red, crystal violet and thioflavine) were negative. Renal ultrasound showed normal-sized kidneys. A renal biopsy was performed (Fig. 2). Light microscopy revealed