Tattoos and laser removal: what does scientific evidence say?

What really happens in the dermis?

One of the most relevant advances in recent scientific literature concerns the increasingly precise understanding of the biological dynamics of tattoo pigment.

Contrary to the intuitive assumption that ink remains statically “deposited” in the skin, histological evidence demonstrates that tattoo pigment localizes within the dermis, where it is primarily engulfed by dermal macrophages and fibroblasts¹.

This point is fundamental: tattoos do not persist because the pigment is inert, but because it becomes integrated into a dynamic equilibrium mediated by the cutaneous immune system.

The “Capture–Release–Recapture” Mechanism

The study by Baranska et al.¹ represented a pivotal step in understanding tattoo persistence. The authors demonstrated that:

• dermal macrophages phagocytose the pigment;

• when these cells undergo physiological turnover, they release the pigment;

• the released pigment is immediately recaptured by newly recruited resident macrophages.

This continuous capture–release–recapture mechanism explains:

• the long-term stability of tattoos;

• their resistance to spontaneous removal;

• the need for an external intervention (laser) to significantly disrupt this equilibrium.

In other words, tattoos persist not because of biological inactivity, but due to an active and regulated cellular process.

An additional well-documented aspect concerns the possibility that a fraction of tattoo pigment may be transported through the lymphatic system and accumulate in regional draining lymph nodes²–⁴.

This phenomenon has been particularly observed in the context of sentinel lymph node biopsy, where pigment deposits may occasionally mimic pathological findings². It is important to emphasize that:

• the presence of pigment in lymph nodes represents a benign and incidental finding;

• it has not been associated with systemic lymph node pathology;

• no epidemiological data demonstrate an increased oncologic risk in tattooed individuals²–⁵.

Lymphatic migration of pigment simply reflects the normal function of the immune system, which is responsible for the capture and drainage of exogenous particles introduced into tissues.

Understanding this biological dynamic is essential for correctly interpreting laser tattoo removal.

If pigment persistence is maintained by an active cellular equilibrium, it becomes evident that its elimination:

• cannot be immediate;

• cannot occur in a single treatment session;

• requires adequate time to allow physiological drainage and clearance mechanisms to operate¹.

Laser removal acts by disrupting this equilibrium through the selective fragmentation of pigment particles; however, the final elimination of fragmented material ultimately depends on the body's normal biological processes.

To date, the scientific literature does not support a documented increase in oncologic risk either in tattooed individuals or in patients undergoing laser tattoo removal¹–³.

Recent studies contribute to refining our understanding of the biological and chemical mechanisms involved, but they do not call into question the clinical safety of the procedure when properly performed.

Reference:

1. Baranska A, Shawket A, Jouve M, et al. Unveiling skin macrophage dynamics explains both tattoo persistence and strenuous removal. J Exp Med. 2018;215(4):1115–1133.

2. Kim JY, et al. Tattoo pigment mimicking metastatic malignant melanoma in sentinel lymph node. Ann Dermatol. 2015;27(1):97–99.

3. Kluger N, Koljonen V. Tattoos, inks, and cancer. Lancet Oncol. 2012;13(4):e161–e168.

4. Sepehri M, Sejersen T, Qvortrup K, Lerche CM, Serup J. Tattoo pigments are observed in the Kupffer cells of the liver indicating blood-borne distribution of tattoo ink. Dermatology. 2017;233(1):86–93.

5. Serup J, Kluger N, Bäumler W, eds. Tattooed Skin and Health. Basel: Karger; 2015.

6. Hauri U, Hohl C, Kappeler A, et al. Chemical composition of tattoo inks and potential health risks. J Hazard Mater. 2015;282:127–135.

7. European Chemicals Agency (ECHA). Restriction of hazardous substances in tattoo inks and permanent make-up. REACH Regulation, EU.

8. Bauer EM, Ricci C, Cecchetti D, et al. Toxicological problems of tattoo removal: characterization of femtosecond laser-induced fragments of Pigment Green 7 and Green Concentrate tattoo ink. Arch Toxicol. 2025;99(4):1355–1369.