A case of hypopituitarism due to inflammatory myofibroblastic tumor of the sella turnica.

An 18-year-old man with 4-year history of central diabetes insipidus and partial pituitary dysfunction was admitted to our hospital because of headache and nasal discharge. Magnetic resonance imaging (MRI) revealed abnormal mass in the sella turnica invading into the cavernous sinus and sinus maxillaries along with thickened tentorium cerebelli. Histopathology of the mass in the sinus maxillaries revealed spindle-shaped cells arranged in a fascicular pattern with varied myxoid and collagenized regions with various inflammatory cells. Immunostaining revealed the spindle-shaped cells were positive for smooth muscle actin. These features were identical to those of inflammatory myofibroblastic tumor (IMT). He was diagnosed with IMT in the sella turnica and other regions. Corticosteroid therapy improved clinical symptoms and follow-up MRI revealed amelioration of the thickened tentorium cerebelli. However, the other lesions were unchanged and pituitary dysfunction did not improve. Although rare, IMT should be considered in the differential diagnosis of a sellar mass. Early treatment with corticosteroid therapy may reduce the risk of disease progression.