A recent case series (A Cordesse et al. JPGN Reports; 2020. November 2020 – Volume 1 – Issue 2 – p e007doi: 10.1097/PG9.0000000000000007. Chronic Recurrent Multifocal Osteomyelitis in Pediatric Crohn Disease, A Paradoxical Effect to Antitumor Necrosis Factor Alpha) reported on paradoxical Chronic Recurrent Multifocal Osteomyelitis (CRMO) which I have seen in one of my patients as well.

Key points:

• In patients receiving anti-TNF agents which are usually effective for CRMO, CRMO may develop paradoxically and may be associated with a psoriaform reaction.
• At the time of diagnosis of paradoxical reaction, all patients were in remission due to anti-TNFα efficiency. Trough levels of anti-TNFα were in the expected range, and there were no anti–anti-TNFα antibodies.
• All patients recovered after discontinuation of infliximab (n = 2) or adalimumab (n = 1). 

My take: This study describes a rare adverse effect of anti-TNFα agents. If CRMO develops while on one of these agents, an alternative treatment is needed.