Lambert's injury woes were compounded by a 2-1 home defeat to bottom club Fulham on Saturday, for which he was without 10 squad members.
Christian Benteke is set for a long spell on the sidelines with an Achilles injury, while Fabian Delph, Gabriel Agbonlolahor and Karim El Ahmadi all missed the game at Villa Park.
Jores Okore, Libor Kozak, Charles N'Zogbia, Gary Gardner and Nicklas Helenius are also ruled out through injury, while Chris Herd is unavailable due to personal reasons.
"If you go through them, Okore is nearly a full season, Kozak virtually half-a-season, Benteke six months or so and Charles, so they've been major, major injuries, they're not just strains or anything," Lambert told the Birmingham Mail.
"As well as Christian, we were without Gabby and Fabian. It's a big chunk and if you throw in El Ahmadi as well because he's been playing really well of late.
"That's four lads that have been playing virtually the whole season for us and when you lose that it is a big chunk to lose.
"I think a club this size needs a big squad and these conversations will happen probably in a few weeks' time."
Part and parcel
Lambert insists Lerner is well aware of the situation and expects discussions will be opened shortly about filling the voids left by injury.
"We've not spoken about it yet," he added.
"I spoke to Randy on Friday and he knows the situation with Christian. I think the most important thing is to get through this season and then there will be time to sit with Paul Faulkner and Randy and see what's happening.
"There's always been injuries, but that's part and parcel of the game. But when you lose four of them that's a big chunk out of our side."
Lambert was also keen to emphasise that Villa's growing list of injuries was coincidental, rather than a result of training methods.
"In the majority of the cases there was nobody near the lads," he said.