AIMEE KHOO1,2, NICHITA GAVRILESCU1, ALAN PHAM1, KATE ROBSON1
1The Alfred Hospital, Melbourne, Australia, 2Royal Darwin Hospital, Tiwi, Australia
Biography:
Aimee is a first year nephrology advanced trainee at Royal Darwin Hospital.
Background:
Immune complex mediated membranoproliferative glomerulonephritis (MPGN) is a rare form of glomerulonephritis where mechanistic understanding of pathophysiology is rapidly evolving and being actively researched.
Here we present a rare case where steroids used in the treatment of MPGN resulted in the unmasking of seronegative myasthenia gravis – an autoimmune disorder characterised by excess autoantibody production and thymic dysregulation.
Case Report:
A 73 year old female presented with hypertensive urgency, fluid overload and subnephrotic range proteinuria. Her renal biopsy demonstrated a membranoproliferative pattern of injury, with mild interstitial inflammation and no fibrosis. Immunohistochemistry stained strongly positive for C3 and IgG and weaker staining for IgA/IgM/C1q/C4. Small and large electron dense deposits were seen and on ultrastructure were composed of small fibrils in the mesangial matrix and along the subendothelial aspect of the glomerular basement membrane. Serum C3 and C4 complement levels were normal throughout her course and further investigations did not identify any occult malignancy or paraproteinaemia. There were no identified autoantibodies to complement factors and a complement genetic testing panel was negative. She was commenced on high dose prednisolone which saw an improvement in both renal function and albuminuria. The high dose prednisolone unmasked symptoms of severe fatigue and bilateral eyelid drooping. She went on to have a diagnosis of seronegative myasthenia gravis, confirmed with single fibre electromyography and in the absence of acetylcholine receptor and muscle-specific kinase antibodies. Her prednisolone was tapered and mycophenolate was introduced resulting in stabilisation of both conditions.
Conclusions:
To our knowledge this is the second published case report of the concomitant treatment of myasthenia gravis and MPGN, two rare autoimmune disorders with potential shared pathophysiological processes.