Page 34 - An Introduction to Laser Tattoo Removal

Chapter 2 – Fundamentals of Laser Tattoo Removal v1.0
Histology of Tattoos
What is a tattoo, histologically?
In its simplest form, a tattoo is simply ink particles which have been ‘forced’ into the skin, usually using needles or similar. But where does this ink go?
Histological examinations reveal tattoo ink particles found inside large phagosomes (learn more here) in the cytoplasm of keratinocytes and phagocytic cells such as fibroblasts, macrophages and mast cells. Around four weeks after the ink is inserted into the skin, the basement membrane of the epidermis is reforming, and some ink particles may be found in the basal cells in the basal layer. Most ink particles which were previously in the epidermis will have sloughed off in that period, which appears, to the eye, as a reduction in the ‘brightness’ and ‘intensity’ of the new tattoo.
After this time, most ink will now be found in the keratinocytes, macrophages and fibroblasts in the dermis. Very few are located in the mast cells, endothelial cells, pericytes, Schwann cells or in the lumina of the blood and lymphatic vessels. Virtually none will be in the dermal matrix tissue.
Epidermis
After a relatively short time (typically 2 to 3 months) following insertion, virtually all ink particles/aggregates are located within fibroblasts and macrophages, often adjacent to blood vessels beneath a layer of fibrotic (scar) tissue. The tattooing process is damaging to the skin and will typically result in some scar formation, although it is rarely visible to the naked eye.
The trauma of tattooing induces the skin’s natural ‘wound response mechanisms’ which immediately attempt to repair the various tissues of the skin (this well be discussed in more detail later in this Chapter).
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Chapter 2 LEVEL A Laser Tattoo Removal
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Ink particles – relatively small and concentrated into layers inside cells
Dermis
Figure 11 – Histological Section of a Professional Tattoo (x100, H&E stain)