Tattoo pigment agglomerates measured in skin biopsies by computerised light microscopy: Study of 161 patients with adverse reactions in black and red tattoos.

Background: Black tattoo reactions are suggested to be foreign body reactions manifested as papulo-nodular inflammation that is associated with active sarcoidosis.
Aim: To study the morphology of black and red pigment agglomerates in skin biopsies from tattoo reactions, referenced to clinical diagnoses.
Method: Agglomerate count, area, width, height, circumference and circularity were measured in 161 patients by light microscopy (Olympus BX51™); 161 unstained skin biopsies from 64 black tattoo reactions and 97 reactions in red tattoos with allergy. Images (Jenoptic Gryphax RGB camera) were taken through a 40× objective using immersion oil. Computerised analysis of agglomerates was performed using ImageJ software. Student t test, chi-square test, Fisher Exact test, ANOVA and Bonferroni tests were applied.
Results: Comparison of black and red pigment agglomerates showed no overall differences in count, area, width, height or circumference. However, in black tattoo reactions, the count of agglomerates was higher in patients with sarcoidosis (P = .009) vs no sarcoidosis. Black agglomerates were more circular shaped as compared to red, P = .023. In red tattoo reactions, agglomerates in patients with allergic cross-reactivity were slightly more circular (P = .036) vs patients with milder allergy. The count of red agglomerates was lower in patients clinically typed excessive hyperkeratosis (P = .041) compared with other clinical types of allergy.
Conclusion: Patients with reactions in black tattoos associated with sarcoidosis have increased count of pigment agglomerates vs those without associated sarcoidosis indicating that black pigment agglomeration is one among a number of factors triggering sarcoid tattoo complication. Circular shape of agglomerates may code for bioactivity.
(© 2019 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)