PMC3279960_01
Preoperative brain computed tomography scan conducted without contrast showing a high-density and extraaxial mass in the right parietal convexity and peritumoral brain edema
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F1
A computed tomography (CT) examination of the head that was conducted without contrast showed a high-density and extraaxial mass in the right parietal convexity, and peritumoral brain edema was clearly observed [Figure 1].
(a) T2-weighted magnetic resonance images. (b) Fluid-attenuated inversion recovery. (c) T1-weighted images. (d) T1-weighted magnetic resonance image with gadolinium
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F2
Enhanced magnetic resonance imaging (MRI) revealed an extraaxial, dural-based, and homogeneously enhanced mass with clear borders that was compatible with a meningioma en plaque [Figure 2].
(a) Photomicrographs of the frozen sections showing inflammatory cell infiltration, which consisted of lymphocytes and plasma cells, which was initially interpreted as a hematologic disorder or an inflammatory pseudotumor. (b) Paraffin-embedded sections show a hypercellular pattern with features of polymorphous and mixed inflammatory infiltrate that was composed of mainly histiocytes in a background of collagen fibers. (c) The cytoplasm in some histiocytes was foamy and eosinophilic. Some histiocytes were seen to engulf viable lymphocytes, and this was thought to be indicative of emperipolesis (arrow)
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F3
A frozen section of the lesion showed inflammatory cell infiltration, which mainly consisted of lymphocytes and plasma cells, and the presence of these cells was initially interpreted as some kind of hematologic disorder or inflammatory pseudotumor [Figure 3a]. Paraffin-embedded sections, however, showed a hypercellular pattern with features of polymorphous and mixed inflammatory infiltrates that were composed mainly of histiocytes in a background of collagen fibers [Figure 3b]. Some histiocytes were seen to engulf viable lymphocytes, which was thought to reflect emperipolesis (lymphophagocytosis) [Figure 3c].
Photomicrograph of immunostaining. These histiocytes were immunopositive for (a) S-100 protein and (b) CD68, but negative for (c) CD1alpha
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These histiocytes were immunopositive for S-100 protein and CD68, but negative for CD1alpha [Figure 4].