Objective:

We described an atypical case of IgG4 related hypertrophic pachymeningitis misdiagnosed as systemic lupus erythematosus (SLE) hypertrophic pachymeningitis.

Background:

Hypertrophic pachymeningitis (HP) is a relatively uncommon disease associated with focal or diffuse thickening and fibrosis of duramater secondary to chronic dural inflammation. The inflammation could be idiopathic or secondary to infections, underlying tumor, autoimmune or inflammatory diseases (SLE, IgG4-RD, Rheumatoid arthritis, sarcoidosis). We present a case of IgG4 related HP initially misdiagnosed as SLE-HP

Design/Methods:

A 45-year-old african-american woman presented with an acute episode of generalized tonic clonic seizure(GTCS). On evaluation she also complained of severe headache persisting for 5-20 minutes which was followed by bilateral lower limb numbness from the past few months. Neurological examination was completely normal. She has a significant past history of SLE manifested in the form of interstitial lung disease and lupus arthritis for the last 20-years.  Magnetic resonance imaging (MRI) brain revealed thick duramater 80*41mm in length and 6.3mm width located in left parietal convexity.

Results:

Excisional biopsy of duramater revealed chronic lymphoplasmacytic inflammation. Blood investigation revealed positive antinuclear antibody (ANA 1:320, Speckled pattern), ribonucleoprotein antibody (RNP), small nuclear RNP (snRNP) and nucleosomal antibody. She was diagnosed with SLE mediated HP and continued on hydroxychloroquine and prednisone which did not resolve her symptoms. Repeat staining of her dural biopsy with IgG was positive for IgG4 cells with greater than 50% high-power field and IgG4/IgG ratio greater than 40%. She was diagnosed with IgG4-HP and started on Rituximab which resulted in complete resolution of her symptoms.

Conclusions:

Neurological involvement in IgG4-RD is extremely rare, with most cases presenting as HP and hypophysitis. Histopathological studies with IgG staining should be done for confirmatory diagnosis in all cases of HP. While SLE mediated HP is responsive to steroids, rituximab is considered as immunosuppressive drug of choice for IgG-HP cases.