Anti-neutrophil cytoplasmic antibody- associated pauci-immune glomerulonephritis in a patient with chronic lymphocytic leukaemia

A 71-year-old woman presented to us in August 2012 with a rash over both lower limbs. Blood tests revealed leukocytosis with white cell count of 22 x 109 /L (neutrophil 1.6 x 109 /L, lymphocytes 20 x 109 /L). Serum creatinine level was 53 μmol/L and serum albumin 42 g/L. Urinalysis showed no albuminuria or microscopic haematuria. Bone marrow biopsy confirmed the diagnosis of chronic lymphocytic leukaemia (CLL). Fluorescence in-situ hybridisation showed deletion of chromosome 11q22~23. Computed tomography revealed multiple enlarged lymph nodes in different regions such as submental, bilateral jugular, left supraclavicular fossa, mediastinal, hila, axillary, porta hepatis, para-aortic and bilateral common iliac regions. Chlorambucil 2 mg twice weekly was prescribed and the patient was followed up regularly in our clinic. During this period she had two episodes of sepsis that were treated successfully with antibiotics. In October 2013, she was noted to have progressive bilateral lower limb swelling and facial puffiness. She also reported frothy urine but no gross haematuria. She denied taking any herbs or over-the-counter medication. Physical examination was unremarkable except for pitting oedema over both lower limbs. Urinalysis revealed the presence of 10-50 red blood cells/cm2. The spot urine protein-to-creatinine ratio was 13.1 g/g. Her serum creatinine concentration was 364 μmol/L (reference range [RR], 65-100 μmol/L), albumin was 32 g/L (RR, 35-52 g/L), globulin was 40 g/L (RR, 22-36 g/L), haemogloblin was 87 g/L (RR, 134-171 g/L), and white blood cell count was 26.4 x 109 /L (RR, 3.7-9.2 x 109 /L) [neutrophil 3.9 x 109 /L, lymphocytes 22.1 x 109 /L]. The liver function was normal. Anti-nuclear antibody was positive (titre 1:80, homogeneous pattern) but anti-DNA was negative. Her antineutrophil cytoplasmic antibodies (ANCA) were positive with perinuclear staining pattern (pANCA) and the anti-myeloperoxidase (anti-MPO) antibody titre was >100 U/mL (reference level, <5 U/mL). The complement level was normal and hepatitis serology was negative. Urine culture showed no Hong Kong Med J 2016;22:178–80 DOI: 10.12809/hkmj144421