Patent blue is an aniline dye (alphazurin 2 G) used to stain the lymphatic channels prior performing lymphangiography.
0.1 to 2.5% of lymphography procedures.
About 30 allergic reactions and 25 cases of anaphylactic shock have been reported.
No deaths reported.
Exposure to tryphenylmethane dyes: textile industry, cosmetics, print shops, farms, pharmaceutical plants, food processing plants, plaque-disclosing agents in dentistry.
General: anaphylactic shock.
Cutaneous: pruritus, urticaria, angioedema, contact dermatitis.
In the course of routine preliminary testing:
0.14 to 3.5% of patients were positive to an intradermal skin-test.
2.7% were positive to a prick-test.
0.3% were positive to a patch-test.
Scratch, prick, and especially intradermal skin tests, using 1/100000 to 1/100 dilutions. Positive results are often observed in patients presenting immediate generalized reactions.
IgE antibodies have never been detected by RAST.
Histamine release from leukocytes incubated with patent blue.
Possible IgE-mediated hypersensitivity in some cases.
Non-specific histamine release.
Indirect histamine release with activation of the alternative complement pathway.
Predictive skin testing does not detect latent patent blue sensitivity in all cases.
Lymphangiography is seldom performed nowadays.
If absolutely necessary: perform lymphangiography without visualization of lymphatic vessels, use Evans blue (but contact dermatitis has been reported).