Buyout firm Welsh, Carson, Anderson & Stowe is picking up a sizeable gain in its newly announced deal to sell lab-services provider AmeriPath to Quest Diagnostics for $1.23 billion and the assumption of $770 million in debt. The firm paid $658 million for AmeriPath in 2003. The company, which does DNA analysis and cancer diagnostics, has revenue of $800 million. Surya Mohapatra, Quest's CEO, said that the deal would establish the company's leading position in cancer diagnostics as well as establish its reputation in dermatopathology and anatomic pathology. Report