IgG4-related sclerosing pachymeningitis: a previously unrecognized form of central nervous system involvement in IgG4-related sclerosing disease.

IgG4-related sclerosing disease is a distinctive mass-forming lesion with frequent systemic involvement, most frequently the pancreas, salivary glands, and lacrimal glands. This report describes a case manifesting with a previously unrecognized form of central nervous system involvement. The 37-year-old man presented with signs and symptoms of spinal cord compression at the thoracic level 9. Magnetic resonance imaging revealed an elongated dural mass extending from the fifth to tenth thoracic vertebra. Laminectomy and excision of the mass revealed dura expanded by a dense lymphoplasmacytic infiltrate accompanied by stromal fibrosis and phlebitis. IgG4+ plasma cells were increased and the proportion of IgG4+/IgG+ plasma cells was 85%. The patient also had a 1-year history of bilateral submandibular swelling due to chronic sialadenitis. Thus, IgG4-related sclerosing pachymeningitis represents a new member of the IgG4-related sclerosing disease family affecting the central nervous system. It seems that at least a proportion of cases described in the literature as idiopathic hypertrophic pachymeningitis belong to this disease, especially as some patients have other clinical manifestations compatible with IgG4-related sclerosing disease, such as cholangitis and orbital pseudotumor.