An 85-year-old granny was robbed inside a Bronx apartment building on Thursday — continuing the disturbing trend of attacks on the city’s elderly.

The victim was inside the lobby of a building near Randall Avenue and Olmstead Avenue in Castle Hill about noon when a younger male suspect ran inside and snatched her purse, cops said.

The thief then fled the building with her bag, which contained $50 and five credit cards.

Cops said the crook is anywhere from 16 to 20-years-old. He wore a blue hoodie, gray jeans and black sneakers.

There have been over 300 mugging victims citywide over the age of 65 so far this year.