A 60-year-old woman undergoing breast reconstruction developed a bluish tint across her entire body after surgeons injected a dye commonly used to map lymph vessels and nodes. She also produced blue-green urine, and tests revealed methemoglobinemia, a blood disorder that reduces the blood's ability to deliver oxygen.
The case, published in A&A Practice in July 2025 by Gaetano Gazzè and colleagues at Policlinico Umberto I in Rome, involved Patent Blue V, a dye that is regaining popularity as lymphatic reconstruction techniques advance. The authors described the diffuse bluish skin as a previously unreported manifestation of the dye.
An older report from Germany suggests the phenomenon may be rare rather than entirely new. Either way, the case is a vivid reminder that a dye generally considered safe can still produce dramatic, and occasionally dangerous, effects.
A 50-Milligram Injection and a Body-Wide Blue Tint
According to the report's abstract, the patient received a 50-mg bolus of Patent Blue V injected into the skin. Afterward, she developed four notable findings: generalized bluish skin, blue-green urine, a mild drop in her blood oxygen readings on pulse oximetry and methemoglobinemia.
Surgeons inject the dye so it travels through lymphatic vessels and stains them and nearby lymph nodes, making them easier to see. The body clears it mainly through the urine over roughly 24 to 48 hours, which helps explain why urine can turn blue.
The published abstract does not detail her methemoglobin levels, how long the discoloration lasted or how she was treated. The authors' main message was about awareness. Although the dye is generally safe, they wrote, clinicians need to recognize its potential allergic and adverse effects, including misleading oxygen readings and methemoglobinemia, both of which can harm patients.
Why a Blue Dye Can Interfere with Oxygen
Methemoglobinemia occurs when the iron in hemoglobin is oxidized into a form that cannot bind oxygen effectively, as described in the StatPearls clinical reference. Common triggers include drugs such as dapsone, benzocaine and phenazopyridine, along with nitrates and nitrites. Patients may develop bluish skin, shortness of breath and fatigue.
Symptoms track with methemoglobin levels. According to StatPearls, visible bluish discoloration appears above about 10%, anxiety and a racing heart can occur between 20% and 50%, and levels above 50% to 70% can be fatal.
In an odd twist, the FDA-approved treatment for acquired methemoglobinemia is another blue dye, methylene blue, which helps convert hemoglobin back to its oxygen-carrying form.
Blue dyes can also confuse monitoring equipment. Pulse oximeters estimate oxygen levels by shining light through the skin, so a dye in the bloodstream can produce falsely low readings. That makes it harder for anesthesia teams to separate a harmless dye effect from genuine oxygen deprivation, which is why blood gas testing is often needed.
Not the First Time Patent Blue Has Surprised Doctors
Earlier reports show a range of reactions. A case report in Cureus described a 68-year-old woman in Turkey whose oxygen saturation fell steadily after Patent Blue V was used for lymph node mapping during mastectomy. Her methemoglobin level reached 9.2%, and after treatment with methylene blue, it returned to normal within eight hours.
In a case from Melbourne, Australia, a 65-year-old woman weighing 43 kg developed heart rhythm problems and circulatory instability about 35 minutes after receiving 100 mg of the dye during breast cancer surgery with free-flap reconstruction. Doctors first treated it as an allergic reaction, but allergy testing came back negative, and the authors raised the possibility of a dye overdose.
Whole-body blue skin has been described at least once before in a different setting. A report in the journal Endoscopydescribed a 68-year-old man in Germany whose skin turned dark blue all over within about three hours after 6 milliliters of patent blue was injected to mark a colon polyp. The color was gone within 48 hours, and he showed no breathing problems or signs of an allergic reaction. The author also noted that patent blue is used as a food coloring, in products such as blue curaçao and jelly beans.
What It Means for U.S. Patients Facing Lymph Node Mapping
In the U.S., surgeons often use isosulfan blue, a closely related dye, for lymphatic mapping. Its prescribing informationwarns of life-threatening allergic reactions and advises monitoring patients closely for at least 60 minutes after injection. It also notes that the dye can cause falsely low pulse oximetry readings, with the effect peaking around 30 minutes and generally fading by four hours. Case series cited in the labeling put the overall rate of hypersensitivity reactions at about 2%, with effects ranging from hives and itching to shock.
For patients, the key takeaway is that blue skin or blue-green urine after these procedures is usually a known dye effect, but it can occasionally accompany methemoglobinemia or an allergic reaction. People scheduled for lymph node mapping should tell their surgical team about any prior reactions to dyes or medications.
Key Questions Answered
What happened to the patient?
After a 50-mg skin injection of Patent Blue V during breast reconstruction, the 60-year-old developed bluish skin across her body, blue-green urine, a mild drop in oxygen readings and methemoglobinemia.
What is Patent Blue V used for?
Surgeons inject it to stain lymphatic vessels and lymph nodes so they can be identified, including in breast cancer surgery and lymphatic reconstruction.
What is methemoglobinemia?
It is a condition in which hemoglobin is altered so it cannot carry oxygen effectively. It can cause bluish skin, shortness of breath and fatigue, and it can be life-threatening at high levels.
How is it treated?
Methylene blue is the FDA-approved treatment for acquired methemoglobinemia, along with supportive care.
Should patients worry about blue dye before surgery?
Serious reactions are uncommon. Patients should share any history of dye or drug allergies with their surgical team, which monitors for reactions after injection.
Published by Medicaldaily.com
