Schnitzler‐Syndrom Mit Basophiler Infiltration

Schnitzler syndrome is a comparatively rare disease characterized by urticarial lesions and monoclonal IgM gammopathy [1, 2]. Other symptoms/abnormalities include fever, arthralgia, bone pain, lymphadenopathy, hepatosplenomegaly and leukocytosis. Urticarial rash is usually not pruritic and is histopathologically characterized by diffuse dermal cellular infiltrates, mainly comprising neutrophils, i.e. neutrophilic urticaria or neutrophilic urticarial dermatosis [1, 3]. A 76-year-old Japanese man presented with approximately one year’s history of recurrent wheals. These eruptions had not responded to several oral antihistamines. The patient’s medical history included hypertension and benign prostatic hyperplasia. Physical examination revealed wheals and/or patches of urticarial erythema of different sizes on the trunk and extremities, none of which were pruritic (Figure 1a). Each eruption resolved within 1–2 days. The patient also had arthralgia of the wrists, knees, and ankle joints, but his body temperature was normal. Laboratory findings were: white blood cells (WBCs) 7200/μl (4000/μl < normal < 8000/μl) (neutrophils, 81 %; eosinophils, 0 %; basophils, 0 %); platelets, 24.0 × 104/μl (15.0 × 104/μl < normal < 40.0 × 104/μl); AST, 12 U/l (normal, < 30 U/l); ALT, 16 U/l (normal <35 U/l); ALP, 259 U/l (normal, < 340 U/l); γ-GTP, 18 U/l (normal, < 70 U/l); CRP, 1.1 mg/ dl (normal, < 0.3 mg/dl); IgG, 1167 mg/dl (870 < normal < 1700 mg/dl); IgA, 173 mg/dl (110 < normal < 410 mg/dl); IgM, 1119 mg/dl (35 < normal < 220 mg/dl); IgE, 14 IU/ ml (normal, < 170 IU/ml); rheumatoid factor, negative; anti-nuclear antibody, negative. The patient also had slightly elevated levels of serum TNFα (1.97 pg/ml; normal, < 1.79 pg/ml) and IL-6 (2.89 pg/ml; normal, < 2.41 pg/ml). Histopathological features of urticarial erythema included diffuse cellular infiltrates comprising neutrophils and lymphocytes in the upper dermis (Figure 1b, c). Eosinophils were not detected. However, immunohistochemical staining with a basophil-specific BB1 antibody (kindly provided by Dr. Andrew F. Walls, University of Southampton, Southampton, UK) revealed a number of basophils in the upper dermis (Figure 1d, e). The densities of basophils and neutrophils were 43.3 cells/mm2 and 132.5 cells/mm2, respectively. Mast cell densities were 8.8 cells/mm2, as determined by toluidine blue staining (data not shown). Immunoelectrophoretic analysis demonstrated IgM-kappa type monoclonal gammopathy. Bone marrow aspiration biopsy showed no myeloproliferative changes, and the patient was therefore diagnosed with monoclonal gammopathy of undetermined significance (MGUS). Neither lymphadenopathy nor hepatosplenomegaly was detected on computed tomography. The patient was initially administered omalizumab but showed no response. Subsequent treatment with oral colchicine resulted in dramatic improvement of the skin symptoms and arthralgia. DOI: 10.1111/ddg.14255 Schnitzler syndrome with basophil infiltration Clinical Letter