PMC8326081_01
(a and b) Axial computed tomography scan showing a left temporobasal lesion with hypertrophic bone changes. (c and d) Axial postcontrast magnetic resonance imaging showing an extra-axial left temporobasal lesion with extension to the midline subfrontal region with poorly demarcated margins from the left temporal lobe.
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F1
A brain CT was done [Figure 1a and b] showing a dural-based mass with hypertrophic adjacent skull base bone. Brain MRI with postcontrast images revealed an avidly enhancing extra-axial lesion in the left temporobasal and midline subfrontal region with poorly demarcated margins from the left temporal lobe [Figure 1c and d].
(a) Hematoxylin and eosin staining (H & E, x100) showing dura mater involved with meningioma and invaded by a tubule glandular forming tumor; an unusual feature for meningioma. (b) There are prominent nuclear atypia and "Indian filing" (H & E, x200); both of them unfamiliar to meningioma and indicating invasive breast carcinoma. (c) Bone tissue infiltrated with atypical epithelial cells (H & E, x100). (d) Immunohistochemistry staining (IHC, x200) showing strong nuclear staining of tumor cells with GATA3 marker that is characteristic of breast carcinoma. (e) Negative staining of meningioma cells (left) compared to metastatic breast carcinoma (right) with GATA3 markers (IHC, x100). (f) Strong positive staining of breast carcinoma cells with estrogen receptor (ER) marker (IHC, x200). (g) Negative reaction of meningioma cells with ER marker (IHC, x100). (h) Focal nuclear staining of both tumor cells with progesterone receptor marker (IHC, x400).
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F2
Histopathological study of the tumor revealed a WHO Grade 1 (WHO 2016 classification) meningioma containing nests of metastatic breast carcinoma in hematoxylin and eosin staining [Figure 2a-c]. These findings confirmed tumor-to-tumor metastasis and determined the metastasis source from breast carcinoma [Figure 2d-h]. The cranial mass sample as well as the previous breast mass harbored focal areas of immunoreactivity with PR on immunohistochemistry staining [Figure 2h].