A 60-year-old man presents with acute renal insufficiency. He treated his garden last week with a number of herbicides and insecticides, some of which may have contained heavy metals. Laboratory studies confirm oliguria and increased levels of BUN (54 mg/dL) and creatinine (3.7 mg/dL). A renal biopsy is shown. What is the most likely diagnosis?

Nephrotoxic ATN is caused by chemically induced injury to epithelial cells. Because they absorb and concentrate the chemicals, tubular epithelial cells are preferred targets for certain toxins, including some antibiotics, radiographic contrast agents, heavy metals (e.g., mercury), and organic solvents. The photomicrograph shows widespread necrosis of proximal tubular epithelial cells with sparing of distal and collecting tubules. Tubulointerstitial nephritis (choice E) may be a response to certain drugs but features interstitial inflammation.Diagnosis: Acute tubular necrosis