title: Perplexing lesions of the sinonasal cavity and skull base: IgG4-related and similar inflammatory diseases.
abstract: OBJECTIVE
  IgG4-related disease (IgG4RD) causing sinonasal and skull base pathology is uncommonly described. We present a series of suspected IgG4RD patients, with a pertinent review of the literature to highlight diagnostic challenges.
  
  
  METHODS
  Case series.
  
  
  METHODS
  Academic tertiary care center.
  
  
  METHODS
  Case series of patients with IgG4RD or suspected IgG4RD involving the sinonasal cavity and skull base.
  
  
  RESULTS
  We present 4 patients with atypical sinonasal and/or skull base disease who were noted to have IgG4-positive plasma cell infiltration on immunohistochemistry of biopsy specimens. IgG4RD, a recently described entity affecting multiple organs, is characterized by lymphoplasmacytic infiltration and often elevated serum IgG4. IgG4RD can masquerade as malignancy or infection but responds to glucocorticosteroid and immunosuppressant therapy. IgG4RD has been infrequently reported presenting as sinonasal or skull base lesions, and definitive diagnostic criteria for these regions are not established. In our series, IgG4RD was suspected in all 4 patients, but only 1 met all current criteria for definitive diagnosis. All 4 patients, however, responded to corticosteroid therapy, and 1 was placed on long-term azathioprine.
  
  
  CONCLUSIONS
  IgG4RD is rarely described in the sinonasal cavity and skull base, and specific diagnostic criteria for such disease have not been defined. We present a series of patients with IgG4-positive plasma cell inflammatory pathology who were suspected to have IgG4RD. Our series highlights diagnostic challenges associated with these patients. Tumefactive and destructive sinonasal-skull base lesions with a plasma cell-rich infiltrate should incite suspicion of IgG4RD, and immunohistochemistry for IgG4-positive plasma cells should be performed.
authors.affiliation: Department of Otolaryngology, Mayo Clinic, Phoenix, Arizona, USA.
authors.forename: Rachel B
authors.initials: RB
authors.lastname: Cain
authors.affiliation: Department of Laboratory Medicine & Pathology, Mayo Clinic, Phoenix, Arizona, USA.
authors.forename: Thomas V
authors.initials: TV
authors.lastname: Colby
authors.affiliation: Department of Hepatology, Mayo Clinic, Phoenix, Arizona, USA.
authors.forename: Vijayan
authors.initials: V
authors.lastname: Balan
authors.affiliation: Department of Neurologic Surgery, Mayo Clinic, Phoenix, Arizona, USA.
authors.forename: Naresh P
authors.initials: NP
authors.lastname: Patel
authors.affiliation: Department of Otolaryngology, Mayo Clinic, Phoenix, Arizona, USA lal.devyani@mayo.edu.
authors.forename: Devyani
authors.initials: D
authors.lastname: Lal
mesh_terms: D000305:Adrenal Cortex Hormones / Q000008:administration & dosage*; D000368:Aged; D001327:Autoimmune Diseases / Q000175:diagnosis* / Q000188:drug therapy; D001707:Biopsy, Needle; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology*; D007150:Immunohistochemistry; D007249:Inflammation / Q000276:immunology / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D010254:Paranasal Sinus Diseases / Q000175:diagnosis / Q000188:drug therapy / Q000276:immunology*; D010950:Plasma Cells / Q000276:immunology* / Q000473:pathology; D018570:Risk Assessment; D012494:Sampling Studies; D019291:Skull Base / Q000276:immunology* / Q000503:physiopathology; D014057:Tomography, X-Ray Computed / Q000379:methods; D016896:Treatment Outcome
chemical_list: D000305:Adrenal Cortex Hormones; D007074:Immunoglobulin G
keywords: IgG4; IgG4-related disease; autoimmune pancreatitis; plasma cell related inflammation; tumefactive fibroinflammatory lesion