PMC2910471_01
Pre-operative axial (a), coronal (b) and sagittal (c) Gadolinium-enhanced T1-w MR images showing the cystic lesion in the sella.
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It extended into the suprasellar cistern determining a minimal displacement of the optic chiasm (Figure 1).
(a) Intraoperative image showing the pus-like fluid drained at dural opening. (b) Intraoperative frozen section showing round and polygonal cells, with a diffuse growth pattern; no evidence of inflammatory cells or foamy histiocytes.
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Surgical exploration via the endoscopic transsphenoidal route revealed a cystic lesion containing pus-like fluid, which was drained after dural opening (Figure 2(a)). The intraoperative histopathological examination indicated a pituitary adenoma (Figure 2(b)). 
Hematoxylin-Eosin stain. Fragments of intact, normal pituitary gland infiltrated by foamy histiocytes.
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The postoperative full histopathological work-up revealed an inflammatory infiltrate of numerous foamy histiocytes, multinucleated giant cells containing cholesterol clefts, and lymphocytes infiltrating between residual nests of normal pituicytes (Figure 3).
Postoperative immunohistochemical stain. Chronic inflammatory cells reaction with collections of foamy histiocytes (IHC: CD68, fast red).
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On immunohistochemical sections, the infiltrating foamy cells, were strongly positive for CD68, a macrophage marker (Figure 4).
Postoperative coronal (a) and sagittal (b) T1-w MR images, showing no pathological changes in the sellar region.
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A postoperative Gadolinium-enhanced head MRI at 8 months showed a normal pituitary gland with no pathological changes (Figure 5). 