type IV hypersensitivity disease urticaria unexplained periodic fever syndrome Schnitzler syndrome https://rarediseases.info.nih.gov/diseases/12390/schnitzler-syndrome https://www.malacards.org/card/schnitzler_syndrome MONDO:0018304 UMLS:C0524988 EFO:1001165 chronic urticaria with gammopathy MESH:D019873 icd11.foundation:1867840545 chronic urticaria with gammapathy Orphanet:37748 MedDRA:10062908 DOID:4371 NORD:1696 MEDGEN:141892 A rare, underdiagnosed disorder in adults characterized by recurrent febrile rash, bone and/or joint pain, enlarged lymph nodes, fatigue, a monoclonal IgM component, leukocytosis and systemic inflammatory response. GARD:0012390 ICD9:708.8 chronic urticaria with macroglobulinemia SCTID:402415001 autoinflammatory syndrome