Nieto underwent successful laparoscopic surgery Thursday and is expected to miss the next 6-8 weeks.
Nieto (lower body) was moved to long-term injured reserve Tuesday, per CapFriendly.
Nieto (lower body) is still considered out "longer-term" according to coach Mike Sullivan, Penguins play-by-play announcer Josh Getzoff reports Tuesday.
Nieto (lower body) skated for the first time since suffering his injury Friday, Matt Vensel of the Pittsburgh Post-Gazette reports.
Nieto (lower body) was placed on injured reserve Sunday, per CapFriendly.
Nieto will miss Saturday's tilt versus Philadelphia with a lower-body injury, according to Penguins reporter Michelle Crechiolo.
Nieto recorded an assist in Thursday's 4-2 win over Tampa Bay.
Nieto penned a two-year, $1.8 million contract with the Penguins on Saturday, Darren Dreger of TSN reports.
Nieto scored a goal on two shots over 9:42 of ice time in Saturday's 5-3 win over the Panthers.
Nieto scored an empty-net goal in Saturday's 4-2 win over the Blues. He finished with three shots on goal, one hit and two PIM over 15:01 of ice time.