Tattoo pigment agglomerates measured in commercial ink stock products by computerised light microscopy

Background The incidence of clinical complications such as granuloma formation and sarcoidosis is often seen in black tattoos and may be associated with agglomeration of black pigment. Aim To measure count and dimensions of agglomerates in black tattoo inks vs red inks and to compare old inks and new inks of identical brands. Method Examination was performed by light microscopy (Olympus BX51 ™ ) with magnification 40X, immersion oil. Photographs (Jenoptik Gryphax RGB camera) were taken of each ink sample and analysed by ImageJ software; count, area, width, height, circumference and circularity index were measured. Agglomerates were defined as width and height of objects above 800 nm. Twenty‐one new unopened black inks and 17 new unopened red inks were compared. Furthermore, five old black inks and five old red inks, that had been opened and stocked for over 2 years, were compared with new products of the same brands. Results Black agglomerates were area wise and with respect to width, height and circumference significantly larger compared with red agglomerates and more circularly shaped. Count of agglomerates was lower in black inks than in red inks, in accordance with bigger dimensions of black agglomerates. Comparison of old and new inks indicated old inks have larger agglomerates but variable bottle size and storage conditions may have confounded results. Conclusion Pigment agglomerates in black tattoo ink stock products were sized larger than agglomerates in red inks. Agglomerates found directly in black inks may predispose to granuloma formation in black tattoos causing sarcoid reaction.