A 27 y.o. with a hx of sinusitis for two months presents with a seizure

What do you see?

and what is going on the in the L frontal lobe?

Our patient had IgG4-related disease.   This is not a brain abscess but rather a systemic inflammatory condition where tissue is infiltrated by plasma cells that secrete IgG4.  IgG4 related disease can involve multiple sites in the body. It can be found in the heart, lung, GI tract, prostate and brain. There can be considerable organ destruction related to the disease.

IgG4 in the prostate with a dense lymphocytic infiltrate

The pathologic process was first described in 1977 when histologic research was done on 349 cases of Kuttner’s tumor( now known as IgG4-related sialadenitis).  Diffuse infiltration of lymphocytes was noted with plasma cell infiltration and eventual fibrosis. 

IgG4 related disease in the parotid on the R, Mikulicz disease

 Several diseases that have been thought to be unrelated are now linked by the fact that they contain IgG4 secreting plasma cells.  Some of these diseases include:  fibrosing mediastinitis, interstitial nephritis, autoimmune pancreatitis, retroperitoneal fibrosis, sensorineural hearing loss,  and inflammatory pseudotumors.

Our patient received rituximab.  Research is underway to evaluate plamablast-directed therapy with a monoclonal antibody(XmAb5871) which inhibits B-cell function.

Perugino C, Stone J. Treatment of igG4-related disease: Current and future approaches.2016.  Zeitschrift fur Rheumatologies. 75(7):681-686. PMID.27431746(https://www.ncbi.nlm.nih.gov/pubmed/27431746)

Seifert G, Donath K. Zur Pathogenese des Kuttner-Tumors der Submandibularis-Analyse von 4347 Fallen mit chronischer Sialadenitis der Submandibularis  ) on the pathogenesis of the Kuttner tumor of the submandibular gland-analysis of 349 cases with chronic sialadenitis of the submandibular . 24(3):81-92.  PMID 856776( https://www.ncbi.nlm.nih.gov/pubmed /856776

Wallace Z, Deshpande V, et al.  IgG4-related disease: Clinical and Laboratory Features in 125 Patients. 2015. Arthritis and Rheumatology 67(9): 2466-75. PMID 25988916(https://www.ncbi.nlm.nih.gov/pubmed/25988916)