Brain Pathology Case of the Month - September 2017

Contributed by M. Michelle Kameda-Smith1, Boleslaw Lach2, Kesava Reddy1
Departments of Neurosurgery1 and Pathology & Molecular Medicine (Neuropathology)2, McMaster University, Canada


A 72-year-old male initially presented to the neurosurgical service in 2004 with severe headache, seizure and gait instability. The scan demonstrated a pineal space occupying lesion and associated hydrocephalus. An endoscopic third ventriculostomy (ETV) and attempted tumor biopsy was performed, but it was non-diagnostic. Thereafter, he was followed both clinically and radiologically for three years before he was lost to follow-up. During the three years that the patient was followed, the lesion was asymptomatic and showed little increase in size on repeated MRI studies. Eleven years after initial treatment, he was readmitted to the hospital with approximately three-month history of significant gait slowing and instability in addition to intermittent blurred vision. He developed worsening memory along with poor concentration and attention. Many of these symptoms were similar to the episode he experienced prior to his ETV. The CT scan performed on admission demonstrated a pineal region hyperdense lesion (3.7 x 3.3 x 3.6 cm) causing compression of the quadrigeminal plate with effacement of the cerebral aqueduct and quadrigeminal cistern and significant mass effect on the cerebellar vermis (Fig. 1). MRI scans showed a heterogeneously enhancing pineal region lesion causing mass effect on the midbrain, cerebellum and splenium of the corpus callosum. No hydrocephalus was noted. He underwent an infratentorial supracerebellar approach and subtotal resection of tumor.


Microscopic examination revealed small, bland appearing, spindle cells arranged in poorly delineated wavy fascicles on the collagenous background focally reminiscent of keloid (Fig. 2). The nuclei displayed minimal hyperchromasia and no mitotic activity. Slit like vessels were outlined by CD34 and CD31 immunoreactivity. Small areas with increased numbers of capillaries displayed a rich reticulin network. Larger vessels were thick walled and hyalinized. Neoplastic cells were strongly positive for Bcl-2 (Fig. 3), CD34 (Fig. 4), CD99 and Vimentin, and negative for EMA, progesterone and estrogen receptor, S-100 protein, desmin, smooth muscle actin, Factor 13A, GFAP and synaptophysin. There was no sign of infiltration into either the brain tissue or the pineal gland. What is your diagnosis?


International Society of Neuropathology