Thread by @crisdelarco

Ornamental tattoo: macroscopy & microscopy.
🔬Dark particles of tattoo ink stay in the dermis.
#pathology #tattoo
Thread ⬇️

Tattoo ink should be deposited in the dermis, which is a "permanent" layer of the skin: that ensures its durability. Tattoo artists recommend a deepness of 2-3.5 mm, depending on the type of skin.
❌A superficial tattoo may lose color intensity due to epidermal regeneration.

❌If the ink is deposited in the hypodermis, it causes "tattoo blowout": pigment diffuses in the hypodermis and lead to a permanent, blurry halo of colour around the tattoo. It appears immediately after tattoo injection, and it may be mistaken as a hematoma.
📸 (own experience)

In this interesting article, you can learn about the tattoo phases, from introduction to ink to healing:
pubmed.ncbi.nlm.nih.gov/3654039/
1. Inflammatory reaction and necrosis, removal of particles via epidermis
2. Reformation of basement membrane
3. Particles stay in dermal fibroblasts

Inks are mainly composed of metal pigments. Most of them contain metal salts, iron oxides or plastics.
⚫️Black: composed of carbon, nickel or iron.
🔴Red tattoos may be specially allergenic due to their mercury content. Comp: mercury, cadmium, iron or naphtha-derived chems.

Other colors:
🔵cobalt, copper, ferricyanide / ferrocyanide
🟡zink, lead, cadmium, azo-chemicals
⚪️zink, barium, lead, titanium
🟢 chromium, aluminium, azo-chemicals
🟣 aluminium, magnesium

Other components:
➖Carriers: act as solvent for pigments (ethyl alcohol, distilled water, methanol...)
➖Other obscure elements (see tattoo ink regulation below)
Thus, tattoo inks are composed of a colorant + a carrier + many other additional ingredients.

Tattoo inks may contain animal derived products, such as bone char (black colorant), glycerin (stabilizer), gelatin or shellac (binding agents).
Vegan inks include vegetable glycerin or hamamelis.
(the tattoo on the right wrist contains vegan ink)

Tattoo inks are regulated in the US by the Food & Drug Administration, but this regulatory activity is not generally exercised. In the EU, there is no regulation about tattoo inks.
Manufacturers are not required to reveal their ingredients or conduct trials.

Much progress has been made to avoid health risks derived from tattoos, including hygiene standards or informed consent.
⚠️ However, tattoo ink regulation is essential to ensure customer's security and to adequately inform customers about the risks of tattoos.

📃 News! As seen in the US, the EU will limit the use of more than 4000 chemicals and will require the manufacturers to specify ink ingredients since January 2022.
We'll see if it is adequately implemented in practice.

Thanks to your contributions, I've made a little more research:
⚫ It seems like both macrophages & fibroblasts contribute to tattoo stability: a small number of macrophages contain lots of tattoo particles, and lots of fibroblasts contain a few particles karger.com/Article/Abstra…

⚫️ Pigment may be permanent due to a cycle of capture, release and recapture: macrophages die and release pigment, which is taken up by other macrophages before it can disperse.
pubmed.ncbi.nlm.nih.gov/29511065/