Presumably they used markers of some kind before deciding on tattoos to mark the spot for surgeons. Here’s more on the latest about temporary tattoos from a Dec. 21, 2016 news item on phys.org,
Tattoos aren’t just for body art. They can have medical applications, too. Doctors are using them on patients to mark an area for future treatment—particularly for non-melanoma skin cancer such as basal cell carcinoma—but the inks can cause problems. Now scientists have developed a better solution. In the journal ACS Nano, they report a new ink that glows only under certain light conditions and can disappear altogether after a period of time.
A Dec.21, 2016 American Chemical Society news release (also on EurekAlert), which originated the news item, describes the research and the reason for it in more detail,
Patients diagnosed with skin cancer typically have to wait up to three months between a biopsy confirming their condition and treatment. Doctors can mark the spot for possible future treatment using carbon graphite, India ink or fluorescent dye. But these pigments permanently color the skin, and can require laser or surgical removal after a patient has undergone surgery. They can also cause inflammation and discomfort at the site of the tattoo. Kai Chen, Gary S. Chuang, Hsian-Rong Tseng and colleagues wanted to develop a safer, more patient-friendly option.
The researchers created a time-limited pigment by cross-linking fluorescent supramolecular nanoparticles. Under ambient lighting, the nanoparticles are invisible, which would avoid unwanted markings in a patient’s skin. But the pigment glows under light shining at a wavelength of 465 nanometers, so doctors would be able to use a special light to see the dye. Testing in mice showed that tattoos created with these nanoparticles didn’t cause inflammation and lasted for three months. This would be long enough to mark a spot from biopsy through treatment for a non-melanoma patient.
The researchers have provided an image illustrating their work,
Here’s a link to and a citation for the paper,
Cross-Linked Fluorescent Supramolecular Nanoparticles as Finite Tattoo Pigments with Controllable Intradermal Retention Times by Jin-sil Choi, Yazhen Zhu, Hongsheng Li, Parham Peyda, Thuy Tien Nguyen, Mo Yuan Shen, Yang Michael Yang, Jingyi Zhu, Mei Liu, Mandy M. Lee, Shih-Sheng Sun, Yang Yang, Hsiao-hua Yu, Kai Chen, Gary S. Chuang, and Hsian-Rong Tseng. ACS Nano, Article ASAP DOI: 10.1021/acsnano.6b06200 Publication Date (Web): November 30, 2016.
Copyright © 2016 American Chemical Society
This paper is behind a paywall.