Diagnostic value of skin biopsy in autoinflammatory diseases for patients with recurrent fever and urticarial eruption

Similarities and differences in autoinflammatory diseases with urticarial rash, cryopyrin-associated periodic syndrome and Schnitzler syndrome

Cryopyrin-associated periodic syndromes (CAPS) and Schnitzler syndrome (SchS) are autoinflammatory diseases that present with urticaria-like rashes. CAPS is characterized by periodic or persistent systemic inflammation caused by the dysfunction of the NLRP3 gene. With the advent of IL-1-targeted therapies, the prognosis of CAPS has improved remarkably. SchS is considered an acquired form of autoinflammatory syndrome. Patients with SchS are adults of relatively older age. The pathogenesis of SchS remains unknown and is not associated with the NLRP3 gene. Previously, the p.L265P mutation in the MYD88 gene, which is frequently detected in Waldenström macroglobulinemia (WM) with IgM gammopathy, was identified in several cases of SchS. However, because persistent fever and fatigue are symptoms of WM that require therapeutic intervention, it is a challenge to determine whether these patients truly had SchS or whether advanced WM was misidentified as SchS. There are no established treatments for SchS. The treatment algorithm proposed with the diagnostic criteria is to use colchicine as first-line treatment, and systemic administration of steroids is not recommended due to concerns about side effects. In difficult-to-treat cases, treatment targeting IL-1 is recommended. If targeted IL-1 treatment does not improve symptoms, the diagnosis should be reconsidered. We hope that the efficacy of IL-1 therapy in clinical practice will serve as a stepping stone to elucidate the pathogenesis of SchS, focusing on its similarities and differences from CAPS.

Neutrophils in Fixed Drug Eruptions: Correction of a Mistaken Hypothesis

ABSTRACT

Classical histopathological findings of fixed drug eruption (FDE) include a lichenoid/interface dermatitis and perivascular infiltrate in the upper and deep dermis composed of lymphocytes and eosinophils accompanied by pigment incontinence. The presence of neutrophils is also an established finding but is less investigated. Sporadic cases of "neutrophilic FDE" have been reported and suggested as a separate entity, a rare variant, or an early stage of the condition. In this article, we report 16 cases of FDE with quantitative analysis showing that neutrophils are relatively common in FDE (68.8%) and that cases with abundant neutrophils had a significantly shorter onset-to-biopsy interval (3.7 vs. 16.9 days, P < 0.023). Our findings support that neutrophilic FDE more likely represents the early phase of FDE rather than a different entity. The presence of neutrophils expands the histopathological differential diagnosis of FDE to include neutrophilic dermatosis, signifying the value of clinical correlation.