Immunoglobulin G4-Related Spinal Intramedullary Inflammatory Pseudotumor: A Case Report and Literature Review.

Immunoglobulin G4-related disease (IgG4-RD) is an autoimmune disease that affects several organs. An inflammatory pseudotumor is a histologically proven benign tumor-like lesion that most commonly involves the lung and orbit. It is rare in the central nervous system, but rarest in the spinal canal. In this report, we present a case of IgG4-related intramedullary spinal inflammatory pseudotumor, along with a literature review. A 29-year-old male was transferred to the Department of Neurosurgery of Lanzhou University Second Hospital with progressive quadriparesis after numbness and weakness in both lower limbs for 50 days. Enhanced magnetic resonance imaging (MRI) of the spine revealed an isointense signal on T1-weighted images and a hyperintense signal on T2-weighted images from an enhanced mass located at the thoracic vertebrae region, for which a schwannoma was highly suspected. Then, a posterior median approach was adopted. The lesion was resected. The patient received further glucocorticoid after the diagnosis of an IgG4-related inflammatory pseudotumor was established, and the patient's symptoms improved, such as quadriparesis and lower limb weakness. This case highlights the importance of considering IgG4-related inflammatory pseudotumor as a differential diagnosis in patients with lesions involving the spinal intramedullary compartment and lower limb weakness when other more threatening causes have been excluded. IgG4-related inflammatory pseudotumor is etiologically unclear and prognostically unpredictable, and imaging may not help establish the diagnosis of IgG4-related inflammatory pseudotumor due to its resemblance to malignant tumors, and total resection might not be warranted. Glucocorticoid and surgery are usually the first-line treatments used.