An NYPD lieutenant was stabbed in the forearm while responding to a social worker’s request for help with a “violent” emotionally disturbed woman in Brooklyn on Monday, police said.

As the social worker came to the door on East 18th Street, near Albemarle Road, in Flatbush-Ditmas Park about 11:10 a.m., the 44-year-old emotionally disturbed woman lunged at the officers, police said.

The lieutenant, who has been with the department for more than 15 years, was stabbed on his left forearm with a kitchen knife.

He was taken to Kings County Hospital in stable condition, police said.

The suspect was taken into custody and brought to Maimonides Medical Center.