Immunoglobulin A nephropathy associated with juvenile dermatomyositis

Abstract

Sirs, We read with great interest the article in Pediatric Nephrology entitled “Pathophysiological lessons from rare associations of immunological disorders” by Ronco and Debiec [1], following the admission of a patient with juvenile dermatomyositis (JDM) and immunoglobulin A (IgA) nephropathy to our department. A 14-year-old girl presented with a 2-month history of skin rash, fever, muscle weakness and generalized myalgia. Physical examination revealed a heliotropic rash (purplepink in colour) over the eyelids and Gottron’s papules over the extensor surfaces of the wrist and over the dorsal interphalangeal and metacarpophalangeal joints (Fig. 1a). She also had severe weakness and tenderness of the muscles, including the bilateral deltoid muscles, femoral muscles and pelvic girdle. Her erythrocyte sedimentation rate (42 mm/h) and Creactive protein level (8 mg/dl) were increased. Elevated levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH) and creatine phosphokinase (CPK) were found: 233 U/l (normal, <40 U/l), 317 U/l (normal, <40 U/l), 679 U/l (normal, 125– 243 U/l) and 529 U/l (normal, 34–174 U/l), respectively. Serum urea, creatinine, albumin, anti-streptolysin O titre, complement levels (C3 and C4) and serum immunoglobulins (IgG, IgA, IgM and IgE) levels were within normal limits. Findings for auto-antibodies, including rheumatoid factor (RF), anti-nuclear antibody (ANA), anti-doublestranded (anti-ds) DNA, perinuclear anti-neutrophilic cytoplasmic antibody (p-ANCA), cytoplasmic anti-neutrophilic cytoplasmic antibody (c-ANCA) and anti-extractable nuclear antigen (anti-ENA) (anti-Ro, anti-La, anti-Sm, anti-RNP, anti-Scl-70 and anti-Jo-1) were all negative. Urinalysis revealed protein (3+) and blood (1+), and the sediment contained 25–30 red cells per high-power field. Urinary protein excretion was 743 mg/day (580 mg/m per day). Electromyography (EMG) of bilateral deltoid, biceps femoris, iliopsoas and quadriceps muscles demonstrated polyphasic patterns with decreased amplitude and duration, indicating acquired myopathic inflammation. Magnetic resonance spectroscopy (MRS) of the thigh showed decreased creatine peak and elevated choline and myoinositol peaks, reflecting muscle inflammation (Fig. 1b). Based on clinical findings and laboratory examinations, a diagnosis of juvenile dermatomyositis was made. Oral treatment with prednisolone (2 mg/kg per day) and methotrexate (15 mg/m per week) was started. A percutaneous renal biopsy was performed on the 15th day of admission due to persistence of the proteinuria. Twenty-five glomeruli were obtained and showed proliferation of mesangial cells and an increased area of mesangial matrix (Fig. 1c). The glomerular capillary lumens were patent, with normal tubuli and arterioles. There was no cresent and/or fibrosis. Immunofluorescence microscopy revealed segmental deposits of IgA (3+) in the mesangium (Fig. 1d) and was negative for IgG, IgM, C3, C1q and Pediatr Nephrol (2009) 24:2073–2075 DOI 10.1007/s00467-009-1178-x