Cross-reactivity between nonsteroidal anti-inflammatory drugs in fixed drug eruption: Two unusual cases and a literature review.

Nonsteroidal anti-inflammatory drugs (NSAIDs) are among the main causes of fixed drug eruption (FDE). Cross-sensitivity between chemically unrelated NSAIDs has been rarely described in FDE. We report herein two cases of NSAID-induced FDE confirmed by oral provocation test (OPT) with a literature review. Case 1 is a 49-year-old woman who took mefenamic, naproxen and acetaminophen for lumbago. On the second day, she noticed three erythematous plaques, located in the upper lip, chin and the right hand, which faded spontaneously, leaving residual patches. Three months later, she took mefenamic acid with reactivation of the same plaques. She received naproxen. On the same day, she exhibited a reactivation of lesions with the development of a new one. These lesions have disappeared leaving hyperpigmented sequelae. After negative patch test to naproxen, an OPT was performed with positive reaction, observed on the third day. To establish the cross-reactivity, she underwent OPTs, which gave positive results to indomethacin, ketoprofen and tiaprofenic acid. Case 2 is a 52-year-old woman who presented painful dusky-red macules, located in the right and left wrists, 24 hours after taking mefenamic acid. She described two similar events that occurred in the past with an undefined drug and piroxicam. Patch tests to lysine acetylsalicylate, mefenamic acid, piroxicam, naproxen and celecoxib were negative. OPTs to the same NSAIDs gave positive results to lysine acetylsalicylate, piroxicam and mefenamic acid. Thirteen case reports, seven case series and one retrospective analysis, including cases with confirmed cross-reactivity between NSAIDs, were reported in literature. Clinicians should be aware of such phenomenon.