Management of Schnitzler’s syndrome

Schnitzler Syndrome: Insights into Its Pathogenesis, Clinical Manifestations, and Current Management

Schnitzler syndrome is a rare disorder characterized by a chronic urticarial rash associated with immunoglobulin M (IgM) monoclonal gammopathy. Schnitzler syndrome shares strong clinicopathologic similarities with monogenic IL-1-mediated autoinflammatory disorders and is now considered an acquired adult-onset autoinflammatory disease. The spectacular effect of interleukin-1 inhibitors demonstrates the key role of this cytokine in the pathogenesis of the disease. However, the physiopathology of Schnitzler syndrome remains elusive, and the main question regarding the relationship between autoinflammatory features and monoclonal gammopathy is still unanswered. The purpose of this narrative review is to describe what is currently known about the pathogenesis of this peculiar disease, as well as to address its diagnosis and management.

Monoclonal gammopathy of clinical significance: what the rheumatologist needs to know

Monoclonal proteins can provide important information on the diagnosis of several non-malignant systemic inflammatory disorders. At low concentration, they most commonly represent monoclonal gammopathy of undetermined significance (MGUS), whereas high concentrations often signify plasma cell myeloma or B-cell lymphoma. However, several rare inflammatory conditions associated with variable concentrations of monoclonal proteins, systemic symptoms, and organ dysfunction also exist. These conditions are termed monoclonal gammopathies of clinical significance (MGCS). Patients with MGCS might present to rheumatologists with undiagnosed systemic inflammatory disorders and the monoclonal protein provides an important, underappreciated clue for diagnosis. In this Review, we provide an approach to distinguishing MGCS from MGUS and lymphoid neoplasms, focusing on four rare MGCS that rheumatologists must recognise: scleromyxedema, Schnitzler's syndrome, idiopathic systemic capillary leak syndrome (also known as Clarkson's disease), and telangiectasias, elevated erythropoietin and erythrocytosis, monoclonal gammopathy, perinephric fluid collections, and intrapulmonary shunting (known as TEMPI) syndrome.

Schnitzler Syndrome: the paradigm of an acquired adult-onset auto-inflammatory disease

Schnitzler Syndrome is a rare acquired auto-inflammatory syndrome defined by an urticarial eruption and a monoclonal gammopathy, mainly of the IgM kappa isotype. It shares many clinical and biological features with other autoinflammatory disorders such as NLRP3-auto-inflammatory disorders (NLRP3-AID, formerly cryopyrin associated periodic syndromes or CAPS) or adult-onset Still disease (AOSD). Hence, recurrent fever, urticarial rash with a neutrophilic infiltrate on skin biopsy (i.e. neutrophilic urticarial dermatosis or NUD) and a significant elevation of blood inflammation markers are commonly found in Schnitzler Syndrome as well as in NLRP3-AID or AOSD. IL-1ß plays a crucial role in the pathogenesis and explains the clinical symptoms of Schnitzler Syndrome. This is emphasized by the spectacular effectiveness of IL-1 blocking therapies, especially anakinra. IL-1 blocking therapies are efficient on the inflammation-linked symptoms but not on the monoclonal component. The evolution is chronic and about 15-20% of patients may develop lymphoproliferative disease, in particular Waldenström disease, a proportion similar to patients with IgM monoclonal gammopathy of undetermined significance, and more rarely AA-amyloidosis.

The First Case Report of Schnitzler Syndrome Presenting with Eye Pain

Schnitzler syndrome is a rare, auto inflammatory condition known to manifest with bone pain, urticarial rash, fevers, relapsing arthralgia, and fatigue. In this case report, we describe a patient who was diagnosed with Schnitzler Syndrome that had initially presented with a unilateral pressure-type headache with a sensation of a 'dagger' stabbing into the back of the eye. He also had an associated ipsilateral redness of the conjunctiva, eyelid swelling, subtle optic disc elevations bilaterally and facial flushing - but with no visual acuity, pupillary, or lacrimatory changes. Anterior segment, fundoscopy, intraocular pressures and extraocular muscle movements were otherwise normal.

Schnitzler Syndrome: a Review

PURPOSE OF REVIEW

We focus on recent advances in diagnosis and therapeutic strategies, as well as on pathogenesis of Schnitzler syndrome.

RECENT FINDINGS

New diagnostic criteria were established, and their external validity was assessed in a retrospective cohort study. The cytokine interleukin-1 (IL-1) plays a crucial role in the pathogenesis of the Schnitzler syndrome, and this explains the spectacular efficiency of IL-1 blocking therapies. The Schnitzler syndrome is now considered as a late-onset acquired autoinflammatory syndrome in which the cytokine IL-1 plays a crucial role. IL-1 blocking therapies are efficient on the inflammation-linked symptoms but not on the monoclonal component. Therefore, they probably don't reduce the risk of the development of lymphoproliferative disorders that remains the main prognostic issue. The link between autoinflammation and the monoclonal component needs to be further elucidated.