Presentation
Headache. Lung cancer two years ago.
Patient Data
35mm x 21mm x 16 mm solitary enhancing right cerebellar hemisphere lesion is identified. This contains focal internal T2 hyperintense lesions with intrinsic high T1 signal and signal loss on gradient sequences likely representing blood product (not shown).
There is moderate surrounding vasogenic edema and effacement of the local sulci.
Arachnoid cyst in left middle cranial fossa. Generalized cerebral volume loss.
Multiple T2/FLAIR hyperintense foci are seen throughout the subcortical white matter, particularly in a periventricular location consistent with chronic small vessel ischemic change.
No hydrocephalus.
No evidence of lung recurrance. Right upper and middle lobectomy. Right paratracheal increased signal uptake likely nodal.
Increased tracer uptake in the hepatic flexure may represent metastasis in this setting, further assessment with colonoscopy suggested.
Case Discussion
Given the history of previous lung cancer, the hemorrhagic right cerebellar lesion with moderate local mass effect is favored to represent a solitary metastasis. A glial tumor is the main differential diagnosis.
The most common cause of a solitary tumor in the posterior fossa in an adult patient is a metastatic lesion.
The lesion was resected.
MICROSCOPIC DESCRIPTION:
The sections show features of metastatic poorly differentiated non-small cell carcinoma, adjacent to cerebellar cortex. The tumor forms anastomosing trabeculae and nests with some areas of necrosis. Glandular structures are absent. The tumor cells have enlarged nuclei, prominent nucleoli and moderate amounts of cytoplasm. There is no evidence of keratinization. No evidence of lymphovascular invasion is seen. The tumor cells are diffusely p63 positive. There is focal staining for CK5/6 and less so with CK7. TTF-1 is negative.
DIAGNOSIS:
R cerebellar lesion: Metastatic poorly differentiated squamous cell carcinoma, consistent with lung primary.
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