The growing popularity of tattoos is complicating the early detection of melanoma and other skin cancers, with dark ink obscuring suspicious lesions and tattoo pigments mimicking metastatic disease in lymph nodes, it is being warned.

In a letter published in the Journal of the European Academy of Dermatology and Venereology [link here], Dr Beata Bergler-Czop and colleagues from the Medical University of Silesia’s Department of Dermatology, Poland highlight the significant diagnostic hurdles tattoos pose in dermatological practice.

“Melanomas are most commonly observed in black and blue tattoos because dark tattoos can obscure clinical malignant modifications and delay clinical diagnoses,” they write, adding that dermoscopic examination is often compromised by pigment artefacts appearing as “black–blue globules” that mask underlying lesions.

Beyond camouflage, the chemical composition of tattoo inks is also a concern, they say. While modern inks primarily rely on organic azo dyes, these can break down under UV light or laser treatment to release carcinogenic compounds such as 3,3′-dichlorobenzidine. Pigments may also contain nanoparticles of titanium dioxide, mercury, naphthalene and other substances with known genotoxic or carcinogenic potential.

Tattoo pigments frequently accumulate in regional lymph nodes, raising further diagnostic confusion. “This may lead to unnecessary excision or dissection due to presumed metastatic melanoma,” the authors note, adding that pigment deposits, which are sometimes still visible after tattoo removal, can mimic cancerous spread during sentinel lymph node biopsy.

Meanwhile, nevi, commonly known as moles, located within tattooed skin present another layer of diagnostic difficulty. These benign lesions can mimic melanoma when viewed through the veil of dark ink, particularly black or blue pigments. “Nevi within tattoos can mimic melanoma, often resulting in unwarranted excisions, scarring and distortion of tattoo designs,” the authors write.

Tattoo-related artefacts can trigger false alarms under dermoscopy, leading to unnecessary biopsies that may carry both clinical and aesthetic consequences for patients. The team say non-invasive imaging tools like reflectance confocal microscopy (RCM), which can differentiate between tattoo pigment and true melanocytic changes, may help avoid overdiagnosis and preserve tattoo integrity while still safeguarding against missed melanomas.

To further improve diagnostic accuracy, RCM can be combined with optical coherence tomography, which is particularly helpful for assessing nevi at the periphery of tattoos or in areas with lower ink density, they add. Together, these technologies offer high-resolution imaging comparable to histopathology and are especially useful in detecting flat, amelanotic or hypomelanotic melanomas that may otherwise go unnoticed.

The team urges regular skin surveillance for tattooed individuals, especially those with multiple moles, atypical mole syndrome, or a family history of melanoma. Whole-body videodermoscopy before and after tattooing is recommended to track changes over time.

“Tattoo artists should be educated on the need to refer clients with suspicious pigmented lesions to dermatologists prior to tattooing,” they write. The same caution should apply before laser removal procedures, they say, as treating undiagnosed malignancies can carry “significant forensic and safety risks”.