Schnitzler syndrome: towards lymphoproliferative process?

Schnitzler syndrome (SS) is a rare autoinflammatory disease first described in 1972. Currently, 748 cases of this syndrome are known worldwide. Main symptoms of this syndrome are urticarial rash (persistent urticaria), monoclonal IgM gammopathy, and signs of systemic inflammation: recurrent fever, joint and bone pain, leukocytosis, elevated C-reactive protein levels, and also typical bone remodeling (osteosclerosis). Some cases of SS may be associated with a somatic mutation p.L265P in MYD88 gene, which is often observed in B-cell diseases that increase the risk of lymphoproliferative disorders. 749th case of SS described in this article is characterized by the presence of most diagnostic criteria of the disease, as well as a characteristic genetic mutation. Patient’s disease was diagnosed 5 years after its onset and raised reasonable suspicions of a lymphoproliferative process with PIgM kappa secretion (22% lymphocytosis + p.L265P mutations in MYD88 gene with an allelic load of 3.4%), accompanied by manifestations of SS. Long-term use of glucocorticosteroids by a patient could have a negative influence at the expression of specific markers during immunophenotyping of hemoblastosis, complicating their detection.