Brain Pathology Case of the Month - April 2009

Contributed by Howard T. Chang1, Reuben V. Cuison2, Renuka Gera3, Elna Saah3, Ajovi Scott-Emuakpor3, Christopher Abood4
1Department of Neurology & Ophthalmology, Michigan State University; 2Capital Pathology, Lansing, MI;
    3Department of Pediatrics and Human Development, Michigan State University; 4Lansing Neurosurgery, Lansing, MI


A 6-years-old African American girl presented with severe headache for several days associated with vomiting, neck stiffness, fever, and unsteady gait. Physical examination was otherwise unremarkable. She was recently treated for otitis media approximately one week prior to admission. Mother reported that the patient had frequent headaches and incontinent of bowel and bladder during the past year. A lumbar puncture showed high CSF protein but no signs of infection. Computer Tomography (CT) (Figure 1) and Magnetic Resonance Imaging (MRI) of the brain (Figure 2) showed obstructive hydrocephalus with a 2.3 cm non-enhancing pineal region mass attached to the tectum. MRI of the spinal cord at this time was negative for metastatic disease (Figure 3).

She underwent right occipital ventriculostomy placement to relieve the hydrocephalus and a suboccipital craniectomy for biopsy and partial resection of the tumor. The ventriculostomy catheter was removed after several days but hydrocephalus recurred. Subsequently, she underwent right frontal endoscopic third ventriculostomy but it did not provide adequate drainage and she returned to the hospital with hydrocephalus about four weeks after initial presentation. A suboccipital craniectomy was thus performed with a supracerebellar approach using stereotactic navigation and microscopic dissection for debulking the residual tumor. Her persistent hydrocephalus was then brought under control with a right occipital ventriculoperitoneal shunt about a week later.

The patient had no neurological deficits including ataxia, headache, nausea or vomiting at the time of initial discharge. She was initially treated with oral temozolomide but showed progression as she developed back pain and had several episodes of urinary incontinence about 2 months after the surgery. MRI revealed extensive coating of the cauda equina and the distal thecal sac consistent with drop metastases. The hydrocephalus had resolved but the residual original tectal lesion appeared unchanged. She then received fractional radiation therapy involving the whole brain (3600 cGy), a boost to the tumor bed (5400 cGy), cervical spine (4600 cGy), and thoracic-lumbar spine (4600 cGy). When it was noted that she continued to progress on this treatment, chemotherapy was resumed with one cycle of PCV. However, she continues to deteriorate, at 5 months after initial presentation, with MRI evidence of leptomeningeal gliomatosis (Figures 4 and 5).


The histopathology revealed a moderately hypercellular tumor with small cells embedded in a loose myxoid fibrillary matrix (Figure 6). The tumor cells have round to oval nuclei with fine chromatin, scant cytoplasm, and long thin processes. Some cells show perinuclear halo resembling oligodendrocytes. No definitive eosinophilic granular bodies or Rosenthal fibers are seen. There are no significant mitoses and there is no evidence of vascular proliferation or necrosis. Immunocytochemistry shows that most tumor cell nuclei are positive for S-100. The matrix has many GFAP-positive processes but most cell bodies appear negative for GFAP. Many neurofilament protein and synaptophysin positive processes are also found in the background. A fluorescence-in-situ-hybridization (FISH) study showed no evidence of chromosomes 1p and 19q deletions. The Ki67 labeling index is relatively low, at about 2 to 6%, in most regions, but focally it is up to 20% (Figure 7).


International Society of Neuropathology