Pineal tumor of intermediate differentiation and post shunting corpus callosal damage
Presentation
Headache.
Patient Data
A circumscribed pineal region mass compresses and obstructs the aqueduct with resultant obstructive hydrocephalus and marked inferior bowing of the floor of the third ventricle and upward bowing and thinning of the corpus callosum.
The mass enhances and has fairly low ADC values similar to adjacent brain. Pineal calcifications appear displaced peripherally.
Conclusion
Pineal mass favors a pineal parenchymal tumor with obstructive hydrocephalus.
The patient went on to have a biopsy.
Histology
Sections show fragments of a cellular tumor. The tumor forms sheets of cells, with only the occasional small rosette seen. The tumor cells are monomorphic, with round-to-oval nuclei, finely stippled chromatin, and eosinophilic-to-pale cytoplasm. There are between 1 and 2 mitoses per 10 high-power fields. There is no necrosis and no nuclear atypia. There are plentiful calcifications.
Immunohistochemistry
The tumor cells are diffusely and strongly positive with synaptophysin. Occasional scattered cells are positive with NFR. The topoisomerase proliferation index is approximately 9-10%.
Final diagnosis
Pineal parenchymal tumor of intermediate differentiation (WHO grade 3)
Post-op / post-shunt
A right-sided shunt catheter has been introduced, the tip in the body of the left lateral ventricle. The ventricles are much smaller than pre-operatively, and the corpus callosum now appears to have lower attenuation.
6 month later
The corpus callosum is swollen and irregular with high T2 signal. Note the redundant floor of thrid ventricle. The pineal mass has substantially reduced in size in keeping with response to therapy.
5 years later
Corpus callosum is somewhat less swollen but still demonstrates extensive post-decompression callosal damage. The pineal tumor has not recurred.
Case Discussion
Pineal parenchymal tumors of intermediate differentiation are uncommon tumors of intermediate grade, as the name suggests; they are worse than pineocytomas but better than pineoblastomas. Like other pineal region masses, they can compress the midbrain, resulting in obstructive hydrocephalus.
Decompression of longstanding hydrocephalus can result in post-shunting corpus callosum damage.
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