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| T1 sagittal pre gad | T1 coronal post gad | T1 axial post gad |
Diagnosis: Invasive pituitary macroadenoma with secondary streptococcal meningitis
Pituitary adenoma is the most common juxtasellar mass and represents 10% of all primary brain tumors. An adenoma is considered "macro" if it is greater than 10 mm in diameter. They are often associated with necrosis and hemorrhage. Most occur in adult women and are hormonally active. One third of pituitary adenomas secrete prolactin. Other hormones which may be seen are GH, corticotropin, FSH, LH, and TSH. Pituitary macroadenomas typically expand the sella and have a suprasellar component which may invade the cavernous sinus and elevate the optic chiasm. Adenomas will encase but not narrow the carotid arteries. Enhancement is intense but may be heterogeneous. Pre-contrast signal is usually isointense on T1. This is a case of an invasive macroadenoma which eroded through the sella into the sphenoid sinus and clivus resulting in a fatal streptococcal meningitis. The leptomeningeal enhancement and effacement of the basilar cisterns and cortical sulci are secondary to edema and inflammation due to the meningitis.
The findings in this case are most compatible with an invasive necrotic pituitary macroadenoma. Craniopharyngioma is much less likely secondary to the lack of calcification, the invasion and the extensive sellar component. Metastasis or the very rare pituitary carcinoma is a possibility particularly if you wanted to tie the sellar mass with the leptomeningeal enhancement. However, these are much less likely particularly in a younger patient. Also, no other parenchymal lesions are present which makes mets even less likely. Sphenoid mucocele may somewhat resemble this however the origin of this mass is in the sella with extension into the sphenoid sinus rather than vice versa. The increased peripheral T1 signal pre-gad within the lesion is probably subacute hemorrhage. Related Cases
