CD13 Occupational hand dermatitis: a rare case of isolated methenamine allergy in nitrile gloves

Abstract A 53-year-old female healthcare scientist was referred for patch testing following an 18-month history of eczematous hands worsening after wearing nitrile rubber gloves at work, where she was also exposed to formalin and xylene. Examination revealed significant hand dermatitis affecting the dorsum of both hands, which improved following application of clobetasol propionate ointment and with 4 months away from work. Patch testing was performed to the British Society for Cutaneous Allergy (BSCA) baseline series; the cosmetic, rubber, epoxy resin, formaldehyde resin, clothing and dye, and fragrance series; and her own blue and green nitrile gloves (wet and dry). The total monitoring period was 9 days, with readings taken at days 2, 4, 7 and 9. Patch testing demonstrated positive reactions to (i) methenamine (2% petrolatum), also known as hexamethylenetetramine, in the cosmetic, rubber and epoxy resin series; (ii) melamine formaldehyde (7% petrolatum) in the formaldehyde resin and clothing and dye series; and (iii) toluenesulfonamide formaldehyde resin (TSFR) (10% petrolatum) in the cosmetic series. In the BSCA baseline series, patch testing was positive to quaternium-15 (1% petrolatum) and diazolidinyl urea (2% petrolatum). Notably, she was positive to her green nitrile work glove when applied wet, but negative to the dry application and to her blue nitrile glove. The baseline series rubber markers (thiuram mix, carba mix, mercapto mix and 2-mercaptobenzothiazole) and all items on the rubber series apart from methenamine were negative. This indicated that methenamine was responsible for the occupational allergic contact dermatitis to her nitrile gloves. Methenamine is an organic compound that has diverse uses including in agriculture as a pesticide and insecticide; in medicine to prevent urinary tract infections as well as tick, lice and mite infestations; in the cosmetic industry as a preservative; and in rubber manufacturing as an accelerator and formaldehyde liberator. Significant coreactivity between methen­amine and other formaldehyde releasers such as diazolidinyl urea, melamine formaldehyde and quaternium-15 has been shown. Interestingly, TFSR, which was positive in our case, may also have a small amount of free formaldehyde in the resin. Coreactivity between formaldehyde releasers and formaldehyde itself has been indicated to be > 50%, although notably formaldehyde was negative in our case. We present this rare case to raise awareness of occupational hand dermatitis secondary to isolated methenamine allergy in nitrile gloves and highlight its coreactivity to other formaldehyde releasers. Furthermore, such allergy would likely be missed unless patch testing is performed to extended series, which should be recommended in all cases of hand dermatitis.