Clinical history: 50 year old female, sellar/suprasellar lesion (H+E and PR immuno).
What is the diagnosis, and features to examine for in this lesion?
Meningioma (Psammomatous subtype)
Meningioma is a common tumor throughout the meninges of the brain and spinal cord, including the sellar region. Immunohistochemistry is positive for vimentin and EMA, and can be PR positive in women. There is a high degree of variability in the microscopic appearance of the tumor, which gives rise to the many sub-types. They are usually circumscribed extra-axial lesions associated with the dura. The cellular features depend on the subtype, and for low grade tumors (WHO grade I) these include:
Meningothelial: bland oval nuclei forming syncytial sheets
Fibroblastic: still meningothelial nuclei, but spindle shaped cells with abundant collagen and forming whorls (a common feature to most meningiomas)
Transitional: mixed meningothelial and fibroblastic
Psammomatous: dominated by numerous psammoma bodies, as in the present case
Angiomatous: vessels of different shapes and sizes dominate the islands of meningothelial tumor cells
Microcystic: cytoplasmic processes that define tiny extracellular cysts (microcysts)
Secretory: PAS positive secretions and intracytoplasmic mucin
Lymphoplasmacyte rich: any type with prominent lymphoplasmacytic inflammation
Metaplastic: any type with metaplastic change (bone, cartilage, fat, myxoid)
Worrisome features that could up-stage the tumor include intermediate subtypes (WHO grade II):