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IgG4-Related Disease/Hypertrophic Pachymeningitis


KEY FACTS

Terminology

  • Idiopathic hypertrophic pachymeningitis

  • IgG4-related hypertrophic pachymeningitis

  • Multiorgan immune-mediated condition, which mimics multiple malignant, infectious, and inflammatory disorders

    • Chronic progressive diffuse inflammatory fibrosis of dura of brain or spine

Imaging

  • Linear low signal mass involving dura with variable mass effect upon cord

  • Low signal linear mass effacing cerebrospinal fluid (CSF) and cord

  • Peripheral enhancement related to peripheral zone of active inflammation vs. chronic central fibrosis

Top Differential Diagnoses

  • Meningioma

  • Lymphoma

  • Tuberculosis

  • Sarcoidosis

  • Dural metastases

  • Venous engorgement (CSF leak)

Pathology

  • Autoreactive IgG4 antibodies observed in IgG4-related disease

    • No evidence they are directly pathogenic

  • Central pathology features

    • Lymphoplasmacytic infiltration

    • Obliterative phlebitis

    • Storiform fibrosis

    • Mild to moderate tissue eosinophilia

Clinical Issues

  • Spinal presentation as mass with myelopathy or radiculopathy

  • Histopathology remains cornerstone of diagnosis

Sagittal T2WI MR shows extensive low signal intensity thickening of the dura involving posterior fossa
and upper cervical dura
. There is severe cord compression with loss of normal cerebrospinal fluid signal from the C1-C3 level.

Sagittal T1WI C+ MR in the same patient shows diffuse enhancement of the dural thickening. Note the variable enhancement with areas that homogeneously enhance
and other areas with more peripheral enhancement
.

Axial T1WI C+ MR shows diffuse enhancement of the markedly thickened dura circumferentially surrounding the cord
.

Axial T1WI C+ MR shows the extension of the diffuse dural enhancement and thickening, including along the tentorium
. Note the lack of direct brain parenchymal involvement.

TERMINOLOGY

Synonyms

  • Idiopathic hypertrophic pachymeningitis (IHP)

  • IgG4-related disease

  • IgG4-related hypertrophic pachymeningitis (IgG4-RHP)

Definitions

  • Multiorgan immune mediated condition, which mimics multiple malignant, infectious, and inflammatory disorders

    • 1st defined for pancreatic involvement in 2003

    • May involve pachymeninges of CNS

      • –

        Chronic progressive diffuse inflammatory fibrosis of dura of brain or spine

IMAGING

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