Inflammatory Myofibroblastic Tumor of the Orbit with Associated Enhancement of the Meninges and Multiple Cranial Nerves

Brain MR imaging of a 50-year-old man who presented to the emergency department with multiple cranial neuropathies (left II, III, V, VI, X), the most acute and prominent being visual symptoms. Axial noncontrast T1-weighted image shows left infraorbital mass with loss of the normal fat plane and replacement by soft tissue intensity that extends along the inferior orbital fissure to the infraorbital foramen and can be seen to involve the pterygopalatine fossa and foramen rotundum (A, black arrows), mildly hypointense on fat-saturated T2-weighted images (B, white arrow). There is abnormal contrast enhancement in those locations on fat-saturated postcontrast images (C, white arrows), along the expected course of both V1 and V2, and left cisternal segment of X (C, white dotted arrow). Abnormal contrast enhancement surrounds the left optic nerve (D, black arrows), and mildly expands the left cavernous sinus (D, white arrows), with abnormal pachymeningeal enhancement as well (D, asterisks). Abnormal enhancement is also along the cisternal segment of V bilaterally (E, white arrows). Coronal postcontrast fat-saturated T1-weighted images demonstrate the mass centered on the infraorbital foramen (F, asterisk), the optic nerve sheath involvement (F, black arrow), and erosion of the left maxillary sinus roof. Diffuse pachymeningeal thickening and abnormal contrast enhancement is also present along the falx cerebri (F and G, white arrows). Meckel cave and the left foramen ovale were also diffusely involved (G, asterisks). Subsequent biopsy of the infraorbital mass (H, 20× magnification) demonstrated mild reactive atypia of fibroblasts, with a nonspecific chronic inflammatory reaction consisting primarily of isolated lymphoid aggregates within fibrous tissue. A few infiltrating lymphocytes and fibroblasts showing mild reactive atypia are also present. The whole picture was indicative of inflammatory myofibroblastic tumor (pseudotumor). The patient’s symptoms markedly improved immediately after steroid therapy, and follow-up imaging was performed numerous times over several months, demonstrating progressive improvement per imaging and improved clinical cranial neuropathies. Axial (I) and coronal (J) contrast-enhanced fat-saturated T1-weighted images performed 2 months after steroid therapy initiation demonstrate marked improvement, with only mild residual infraorbital mass, resolved enhancement of II, cisternal segments of V, X, and resolved pachymeningeal enhancement.