An orphan disease: IgG4-related spinal pachymeningitis: report of 2 cases.

IgG4-related disease is relatively new disease entity and a rare one, and our knowledge of this entity continues to evolve. It was first described in the pancreas and since then has been described in virtually every organ. Spinal involvement resulting in pachymeningitis is rare, and there are only 8 reported cases of the same to date, with the cervicothoracic spine being the most commonly affected region. The authors describe 2 cases in which the patients presented with spinal compression resulting in myeloradiculopathy (Case 1) and radiculopathy (Case 2). Imaging of spine in both cases revealed an ill-defined contrast-enhancing lesion at the lumbar level. Preoperatively, a diagnosis of spinal tumor was made, but intraoperatively no spinal tumor was found. The diagnosis was established histopathologically. The disease has no particular defining features clinically or radiologically and can mimic common spinal tumors. It is important to accurately diagnose this rare entity because of its multisystem involvement and progressive course. Strict treatment guidelines have yet to be formulated. Although histologically this disease can mimic other inflammatory conditions, the presence of storiform fibrosis and an increased number of IgG4-positive plasma cells can help in clarifying the diagnosis.