In our culture, tattoos have become quite the norm.  Whether small and discrete, or full sleeves that are hard not to notice, tattoos have become a common form of self-expression.  But what if your tattoos give you a false positive diagnosis for metastatic cancer?  For one California woman, this nightmare became a reality in 2012 during a PET scan that was meant to stage the severity of her cervical cancer diagnosis. 

The woman underwent the body image scan, which lit up in her lymph nodes.  Bright areas in this type of scan usually suggest to doctors that the cancer had spread to those other places in the body. But in this case, it was not cancer but rather tattoo ink that was causing the scan to light up.  It was only after initial surgery for the treatment of her cancer, that this realization dawned on doctors.  

So how did this happen? And is this false-positive diagnosis something everyone who has tattoos should be worried about?  In the case report, published last month in the journal Obstetrics and Gynecology, researchers stated that the PET/CT fusion scan, a scan which uses a radioactive tracer to make tumors appear as bright spots, showed the 32-year-old woman's cervical tumor, but also lit up in the pelvic lymph nodes. 

From a doctor’s perspective, these scan results, showing brightly lit pelvic lymph nodes, looked suspiciously like cancer metastases.  They were under the impression that the cancer had spread beyond the cervix to other parts of the body.  After surgery was performed to treat the cervical cancer and remove the woman’s uterus, cervix, Fallopian tubes and pelvic lymph nodes, the cells of each were examined. 

To doctors’ surprise, when the lymph nodes were examined microscopically, they found the cells had deposits of tattoo ink instead of the projected cancer.

It seems that the tattoo pigment was what was causing the PET scan to light up.  It is important to note that the woman has over 14 tattoos on her legs, and this large amount may be what contributed to the pigment being found in the lymph nodes. Luckily, in this case, the surgical plan was not altered because of the results of the PET scan. 

However, a secondary treatment plan of radiation was abandoned after the clinical team realized the scan results were not indicative of cancer metastases.  Previously there have been similar cases of tattoo in spreading to the lymph nodes and lighting up on PET scans, namely in cases of melanoma and breast cancer.   However this is the first case that doctors have seen it happen, or been reported in a cervical cancer patient. 

Because of the prevalence of tattoos, it is important that doctors are aware that tattoos, and the ink used, can be mistaken for cancer on PET scans.  Because of the similarity, patients coming in with multiple tattoos, or ones that extend over a large surface area of the body,  it is essential to do further testing as thinking that there is cancer where there isn’t, could change the treatment plan of a patient.

For example, if a patient is believed to have metastatic cancer, chemotherapy or radiation may be suggested before surgery.  Making sure that both patients and doctors know false positives can occur because of tattoos can help people get the right type of treatment, and avoid potentially treating for cancer that doesn’t exist.