IgG4-related meningeal disease: clinico-pathological features and proposal for diagnostic criteria.

IgG4-related disease has evolved from originally being recognized as a form of pancreatitis to encompass diseases of numerous organs including the hypophysis and one reported case of dural involvement. A search of the University of Virginia, Division of Neuropathology files for 10 years identified ten cases of unexplained lymphoplasmacytic meningeal inflammation that we then evaluated using immunohistochemical stains for IgG4 and IgG. Ten control cases including sarcoidosis (4), tuberculosis (1), bacterial abscess (2), Langerhans cell histiocytosis (2), and foreign body reaction (1) were also examined. The number of IgG4-positive plasma cells was counted in five high power fields (HPFs) and an average per HPF was calculated. Cases that contained greater than ten IgG4-positive cells/HPF were considered to be IgG4-related. Five of the study cases met these criteria, including one case of leptomeningeal inflammation. All cases exhibited the typical histological features of IgG4-related disease including lymphoplasmacytic inflammation, fibrosis, and phlebitis. The dural-based lesions appear to represent a subset of the cases historically diagnosed as idiopathic hypertrophic pachymeningitis. While the leptomeningeal process most closely resembles non-vasculitic autoimmune inflammatory meningoencephalitis. Given these findings, IgG4-related meningitis should be considered in the differential diagnosis of meningeal inflammatory lesions after stringent clinical and histologic criteria are used to rule out other possible diagnoses.

Extramedullary hematopoiesis within the clivus: an unusual cause of lower cranial nerve palsy.

We report one year follow up of a case of extramedullary hematopoiesis within the clivus. The imaging findings, brief clinical course, and endoscopic transphenoidal approach are described. A 29-year-old female with thalassemia developed worsening cranial nerve signs. After imaging studies discovered a large clival mass, she underwent endoscopic transphenoidal biopsy of the lesion. Neural compression from exuberant erythrogenesis within tissue normally quiescent of red blood cell production was found to be the etiology of her neural deficit. Treatment for this condition is generally non-operative unless significant neural compression is present. Radiotherapy and anti-neoplastic agents have been used with success.