Pyoderma gangrenosum associated with chronic recurrent multifocal osteomyelitis as a possible paradoxical reaction to anti-tumor necrosis factor-α therapy

Pyoderma gangrenosum following anti-TNF therapy in chronic recurrent multifocal osteomyelitis: drug reaction or cutaneous manifestation of the disease? A critical review on the topic with an emblematic case report

Chronic recurrent multifocal osteomyelitis (CRMO) is a rare autoinflammatory disease, clinically characterized by chronic and recurrent episodes of osteoarticular inflammation, that generally presents in children and adolescents. From a dermatological point-of-view, CMRO can be associated with skin rashes mainly including psoriasis, palmoplantar pustulosis and acne. Pyoderma gangrenosum (PG) is a rare immune-mediated inflammatory skin disease classified within the spectrum of neutrophilic dermatoses that, in some cases, has been reported as cutaneous manifestation in CMRO patients. This paper presents a 16-year female patient diagnosed with CMRO, who presented PG lesions located on the lower leg, that arose after the administration of the tumour necrosis factor (TNF)-α inhibitor adalimumab. Cases of PG have been reported in patients being treated with certain medications, including TNF-α antagonists, leading to classified them in a setting aptly termed "drug-induced PG." In this paper, we discuss the co-occurrence of PG and CRMO, in the light of recent evidence on the pathogenesis of both diseases and giving ample space to a literature review on drug induced PG. In our case, it is plausible that PG could be considered a cutaneous manifestation of CRMO, although the mechanisms underlying this intriguingly relationship remain to be fully unraveled.

Canakinumab treatment in a young girl with refractory chronic recurrent multifocal osteomyelitis associated with pyoderma gangrenosum

BACKGROUND

Chronic recurrent multifocal osteomyelitis (CRMO) is a bone inflammatory disorder characterized by osteolytic, usually multiple, symmetric lesions. Diagnosis is one of exclusion, and no standardized therapies are available. Presumed deregulation of the interleukin (IL)-1β axis, as observed in 2 monogenic autoinflammatory conditions such as Majeed syndrome (LPIN2 mutations) and deficiency of IL-1 receptor antagonist (IL1RN mutations) with CRMO-like bone involvement, suggests the blockade of IL-1 as potentially useful also in this condition, even if scarce data are available.

CASE PRESENTATION

We report the case of a 13-year-old girl affected by a multidrug-resistant and pyoderma gangrenosum-complicated CRMO treated with canakinumab, a human monoclonal antibody targeting IL-1β.

CONCLUSION

In this young patient pyoderma gangrenosum and CRMO showed a rapid and satisfactory response to canakinumab, although over time a decreased efficacy in controlling bone disease was observed.