Hello,

I am Dr. Sangwook Park, a board-certified plastic surgeon at UK Plastic Surgery in Centum, Haeundae, Busan.

When people bump their face and the skin does not split open, most of them feel relieved and move on.

In fact, most trauma patients who visit a plastic surgeon come in with a cut that needs stitches or a broken bone.

Yet sometimes, even when the skin looks perfectly intact, the injured spot starts to sink a few weeks later.

The cause is often a hematoma — blood that pooled beneath the skin.

Today I would like to share a real case from our clinic and explain this easily overlooked problem: the depressed scar that can follow a simple bruise.

1. A case from our clinic

A 9-year-old boy fainted from orthostatic hypotension and struck his right cheekbone on the floor.

There was no open wound and nothing to stitch, so after an orthopedic check-up he was told there was nothing seriously wrong and was sent home.

About a month after the injury, he came to our clinic. Under the skin of his right cheek, the hematoma was still present, and scar tissue had begun to form around it.

The skin surface had no wound, but the area looked slightly sunken and pulled in, almost like a line.

▲ At the first visit

We then performed injections to break down the remaining hematoma and the hardening tissue, three times about one month apart,

and asked the family to do regular massage at home together with a scar ointment.

▲ Before the 2nd treatment

▲ At the 3rd treatment

▲ One month after the final treatment

Photos are published with the guardian's consent. Results may vary from person to person.

2. Why does pooled blood leave a dent?

At the moment of impact, small blood vessels under the skin rupture and blood collects in the fat layer. This is called a hematoma.

A small bruise usually resolves on its own, but a large or long-lasting hematoma is a different story.

As the pooled blood is absorbed, fibrous tissue (scar tissue) grows into the space.

This tissue tethers the skin to the layers beneath it — what we call an adhesion.

If the fat is also damaged and loses volume, the area can end up as a sunken, depressed scar.

A scar can form beneath the skin, not only on its surface.

3. Signs worth checking

• The injured area swelled a lot, and you can feel a lump under the bruise

• The lump has not gone down after several weeks

• Once the swelling settles, the area looks sunken compared with the other side

• When smiling or talking, the spot pulls inward

This is especially common on the cheekbones, cheeks and forehead, where bone lies just beneath a layer of fat.

4. Why is it so easy to miss?

A cut is visible, and a fracture causes obvious pain and deformity, so most people seek care right away.

A hematoma, however, is easy to dismiss: "It is just a bruise, it will fade."

And the dent often appears only after the swelling has completely gone down — by then, the adhesion may already be well established.

5. What to do after an injury

• For the first 1–2 days, apply a cold compress to reduce swelling and bleeding.

• Do not rub the area hard right after the injury.

• If swelling is severe or you can feel a lump, have it checked by a plastic surgeon who treats facial soft tissue.

• Once the acute phase has passed and the hematoma starts to firm up, consistent massage as instructed by your doctor is important to reduce adhesion.

The earlier a hematoma is found and managed, before it hardens, the better the chance of reducing scarring.

6. Treating a depressed scar

Treatment depends on how firmly the scar tissue has settled.

• When scar tissue is just beginning to form: injections to break down the remaining hematoma and hardening tissue, combined with massage. As in the case above, this is often done over several sessions.

• When the adhesion has become firm: subcision to release the tethering tissue, or fat grafting to restore lost volume, may be considered.

The right method and timing vary with the depth of the depression, the degree of adhesion and the patient's age (especially in growing children),

and complete recovery cannot be guaranteed in every case.

Closing

When you injure your face, it may not be over just because the skin did not tear and the bone is fine.

If there is significant swelling and a lump you can feel, we recommend seeing a plastic surgeon even without an open wound.

UK Plastic Surgery is a member clinic of the Plastic Surgery Wound & Scar Network (PSWS),

and we look carefully at wounds and scars after injury from a plastic surgeon's perspective.

Thank you.