Neck Nodules After Collagen-Stimulating Filler

A 2022 case report in the dermatology journal Cutis described a woman who developed ten firm nodules on the front of her neck a few weeks after poly-L-lactic acid (PLLA) was injected there. Despite several treatments, most of the nodules did not fully go away, and the authors concluded that the anatomy of the neck itself was the most likely reason.

Why this was studied

PLLA is a collagen-stimulating injectable. Instead of filling a space directly the way hyaluronic acid filler does, it is meant to prompt the body to build new collagen gradually over several months. It has been used for some years to treat volume loss in the face, and some injectors have extended it to other areas, including the neck, which is an off-label use.

A known downside of PLLA is the formation of small bumps (papules) or firmer lumps (nodules) under the skin. Unlike hyaluronic acid filler, PLLA cannot be dissolved with an enzyme, so these lumps can be harder to manage. For background on how the two products differ, see our article on collagen stimulators versus hyaluronic acid filler.

What happened in this case

The patient was a 38-year-old woman who had received PLLA in several other areas over five years without any problems. This time it was injected with a cannula into the front and sides of her neck to improve skin laxity and lines. The product was mixed well in advance and diluted more than is typical.

About three weeks later, ten nodules appeared, both at the cannula entry points and elsewhere on the neck. Saline injections did not help. She then had four rounds of injections containing a combination of anti-inflammatory and anti-scarring medicines. Two nodules resolved completely and the other eight softened and shrank, but did not disappear. Two of the injected spots developed thinning of the overlying skin, a recognized side effect of steroid injections. At her request, the remaining nodules were surgically removed, and examination under the microscope confirmed filler material.

Why the neck needs caution

The authors looked at the usual explanations for PLLA nodules, such as not mixing the product long enough or not diluting it enough, and felt neither applied here. They concluded that location was the main factor.

On the front of the neck, the skin sits directly over a thin, broad muscle called the platysma, which is closely attached to it. Because there is so little tissue between skin and muscle, product can easily end up inside the muscle by accident. The authors point to earlier reports linking placement in muscle with more nodules, and they advise injectors to be cautious about treating the anterior neck with PLLA. The constant movement of the neck when talking, swallowing and turning the head may also play a part, though that was not tested here. Our article on neck bands and the platysma muscle explains this muscle further.

How strong is this evidence?

This is a single case report. It shows that this complication can happen and how one team managed it, but it cannot tell us how often neck nodules occur after PLLA, or which treatment works best. The authors mention that clinical trials of PLLA in approved areas have reported bumps or nodules in a wide range of patients, roughly from 6% to 44% depending on the study, and suggest off-label sites might carry a higher risk. That range comes from older research with varying techniques, so it should not be read as a current risk estimate for any one person.

What it means for you

For most people, the message is about matching the product to the area. The neck is a delicate zone, and many concerns there, such as crepey skin or horizontal lines, can sometimes be approached in other ways. Our article on injectable options for horizontal neck lines covers some of these. In some cases skincare, sun protection or simply accepting mild changes may be the most sensible choice.

If you are considering any collagen-stimulating injection, it is reasonable to ask whether the area is an approved use, what the injector's experience is with that area, and what would happen if nodules formed. Because PLLA lumps cannot be dissolved, prevention matters more than with hyaluronic acid filler.

People who should avoid or delay collagen-stimulating injections include those who are pregnant or breastfeeding, have an active skin infection in the area, have a history of keloid or abnormal scarring, or have certain autoimmune conditions. Your medical history should always be reviewed first.

It is also worth remembering that results from collagen stimulators build slowly over several months and usually need a series of sessions. That slower pace gives time to reassess between visits, but it also means any nodules may not be obvious until weeks after a session, so attending follow-up appointments is important.

Questions to ask at your consultation

• Is this product approved for the area I want treated, or would it be an off-label use?
• What are the alternatives for my concern, including doing nothing?
• What is the plan if bumps or nodules develop?
• How many sessions are usually involved, and how long until results show?

Frequently asked questions

Can PLLA nodules be dissolved like hyaluronic acid filler?

No. There is no enzyme that breaks down PLLA. Nodules are usually managed with injections of anti-inflammatory medicines, and occasionally surgery, which is why careful technique and area selection matter.

When do PLLA nodules usually appear?

They can appear within weeks, as in this case, but some appear months later. Any new lump after treatment should be checked by the clinic that treated you.

Is collagen-stimulating filler unsafe?

Not in general. It is widely used in approved areas with careful technique. This report highlights that some areas, like the front of the neck, may carry more risk.

If you are weighing options for neck skin or facial volume, HealthPark Medical Aesthetics can review your goals and medical history at a consultation and help you decide whether treatment, a different approach or no treatment suits you best.

Source

Dunn A, Long T, Zarraga M, Aguilera SB. Nodules on the anterior neck following poly-L-lactic acid injection. Cutis, 2022;109(6):E15–E17. Read the study