Black macular patches on parietal peritoneum and other extraintestinal sites from intraperitoneal spillage and spread of India ink from preoperative endoscopic tattooing: an endoscopic, surgical, gross pathologic, and microscopic study.

BACKGROUND: Three cases, including one case report and two clinical images, have been reported of extraintestinal or peritoneal black maculae detected at laparoscopy after colonoscopic tattooing, presumably from intraperitoneal spillage of India ink during tattooing. AIMS: Report three cases of inadvertent extraintestinal tattooing from endoscopic tattooing of intestinal lesions, provide histologic evidence for the presumed pathophysiology, and promulgate recommendations to prevent this complication.
METHODS: Three patients underwent endoscopic tattooing of intestinal lesions using India ink, surgery for lesion removal, and pathologic analysis.
RESULTS: Three patients had black macular patches or streaks identified intraoperatively at extraintestinal sites after endoscopic tattooing of intestinal lesions with India ink: (1) black patches on peritoneum 7 days after colonoscopic tattooing of cecal cancer, (2) black streaks on band connecting cecum to peritoneum 13 days after colonoscopic tattooing of cecal cancer, and (3) blackish band on jejunal mesentery 28 days after tattooing presumptive bleeding jejunal lesion. Pigmentation was detected at both injection and extraintestinal sites in all patients by (1) surgery, (2) gross pathology, and (3) microscopic examination demonstrating intracellular black pigmentation within mesothelial cells and macrophages. Special histologic stains were consistent with a carbon-based pigment, and inconsistent with iron or melanin as the pigment. The proposed mechanism is intraperitoneal India ink spillage from deep intestinal injection, as supported by histologic findings of subserosal pigment accumulation. An alternative histologic mechanism is migration of pigment-laden macrophages via lymphovascular channels.
CONCLUSIONS: Endoscopic injection of India ink using standard sclerotherapy needles can inadvertently tattoo extraintestinal sites in addition to tattooing the primary lesion. Despite its striking appearance, this intraoperative, gross, and microscopic finding is likely not pathologically significant, given its proposed pathophysiology. Surgical recognition of this entity is important, however, to prevent misinterpretation of findings as peritoneal melanoma, endometrial implants, infarcted mesentery, or tattooed cancer. This complication may be prevented by proper tattooing technique.