Figure 1 (A–F) Preoperative magnetic resonance imaging (MRI) examination of pituitary abscess in the setting of a pituitary adenoma. Transverse unenhanced (A) and coronal T1-weighted images after gadolinium administration (B) show a 30×25×23 mm solid contrast-enhancing sellar mass with expansion into the suprasellar cistern and the sphenoid sinus. The mass compresses the optic chiasm, the bottom of the third ventricle, displaces the pituitary infundibulum and the pituitary gland. The lesion is isodense on T2-weighted dark fluid sequence, except of a hyperintense part measuring 4×4×10 mm in the upper part of the lesion (C). T2-weighted sagittal image shows hypointense mass with a hyperintense part measuring 4×4×10 mm in the upper part of the lesion (D). The DWI sequence showed increased signal within the lesion (E) with features of restricted diffusion on ADC map (F). (G–L) Postoperative computed tomography (CT) and magnetic resonance imaging (MRI) after transnasal resection of pituitary abscess in the setting of a pituitary adenoma. Brain CT examination performed on the day of surgery showed no signs of a residual adenoma (G). The follow-up CT examination performed on the day of readmission to the hospital (H) as well as coronal (I) and sagittal (J) T1-weighted images showed heterogeneous lesion with peripheral enhancement. The DWI sequence revealed increased signal within the lesion (K) with features of restricted diffusion on ADC map (L), which may indicate either hemorrhage or pus.