IgG4-Related Disease


KEY FACTS

Terminology

  • IgG4-related disease (IgG4-RD)

  • Chronic fibroinflammatory disease characterized by IgG4(+) plasma cell infiltrates

Imaging

  • Diffusely infiltrating enhancing mass

    • Orbital adnexa (lacrimal gland most common)

    • Dura-arachnoid (IgG4-related hypertrophic pachymeningitis)

    • Pituitary gland, stalk (hypophysitis)

    • Other: Cranial nerves (especially infraorbital nerve), brain (autoimmune-like encephalopathy)

  • MR

    • Isointense to brain on T1WI, hypointense on T2WI

    • Enhances strongly, uniformly

Top Differential Diagnoses

  • Idiopathic inflammatory pseudotumor

  • Meningioma

  • Neurosarcoid

  • Lymphoma

Clinical Issues

  • All ages, but 6th-7th decades most common

    • Exophthalmos, headache

    • Cranial neuropathy

  • Clinical course

    • Glucocorticosteroids → improvement/remission (relapses common if tapered/discontinued)

  • Between 3-30% of IgG4-RD patients have normal serum IgG4 concentrations

  • Elevated serum IgG4 is not diagnostic of IgG4-RD (neither sensitive nor specific)

Diagnostic Checklist

  • Best diagnostic clue is combination of clinical history, physical examination, laboratory, imaging

Axial T1WI MR in an 81-year-old man with decreasing vision in his left eye shows diffuse infiltration of the cavernous sinus
and orbital apices
by soft tissue that is isointense relative to the brain. The lacrimal glands are not affected.

Axial T2 FS MR in the same patient shows that the infiltrates
are hypointense relative to the brain.

T1 C+ FS MR in the same patient shows that the cavernous sinus
and orbital apex infiltrates enhance strongly. In addition, note thickened, enhancing dura-arachnoid
in the left middle cranial fossa.

Coronal T1 C+ FS scan in the same case shows that the dura-arachnoid enhancement is bilateral
, and the posterior orbit is filled with enhancing soft tissue
that surrounds and encases the left optic nerve. Biopsy disclosed IgG4-related disease is shown.

TERMINOLOGY

Abbreviations

  • IgG4-related disease (IgG4-RD)

Synonyms

  • Organ-specific conditions now related to IgG4

    • Mikulicz disease (lacrimal, parotid, submandibular glands)

    • Autoimmune pancreatitis (AIP)

    • Ormond disease (retroperitoneal fibrosis)

    • IgG4-related ophthalmic disease

  • “Idiopathic” pseudotumor (generic)

Definitions

  • Chronic fibroinflammatory disease characterized by IgG4(+) plasma cell infiltrates

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