6‐YEAR‐OLD GIRL WITH HYDROCEPHALUS

CLINICAL HISTORY

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. 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 and Magnetic Resonance Imaging (MRI) of the brain (Figure 1a) 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. She underwent right occipital ventriculostomy placement to relieve the hydrocephalus and a suboccipital craniectomy for biopsy and partial resection of the tumor. Later, a suboccipital craniectomy was thus performed with a supracerebellar approach using stereotactic navigation and microscopic dissection for debulking the residual tumor. The patient had no neurological deficits 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.

Figure 1.

PATHOLOGY

The histopathology revealed a moderately hypercellular tumor with small cells embedded in a loose myxoid fibrillary matrix (Figure 1b). 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 1c).

DIAGNOSIS

Pediatric tectal glioma with focal anaplasia.

DISCUSSION

Mesencephalic tectal glioma is a topographical diagnosis consisting of a heterogeneous group of gliomas in children, with relatively benign and indolent clinical course in most previous case reports 1, 2, 3, 5, 9, 10, 11. Although the histopathological features of this tumor are compatible with a diagnosis of mixed oligoastrocytoma, the FISH study showed that this tumor is negative for co‐deletion of chromosomes 1p and 19q. This finding is not surprising in the light of a recent report that losses of chromosomes 1p and 19q are rare in pediatric oligodendrogliomas (4).

As noted by most previous authors, appropriate management of pediatric tectal gliomas depends on the clinical symptoms as well as the histopathology of these tumors. Due to the relatively indolent clinical course of most pediatric tectal tumors, most authors advocate conservative treatments to manage hydrocephalus 1, 2, 3, 5, 7, 8, 9, 10, 11. However, rare high grade astrocytoma with aggressive clinical behavior also have been reported 6, 12. Among tumors identified in the tectal region, the most common are the pilocytic astrocytoma and fibrillary astrocytoma, and less frequently oligodendroglioma and oligoastrocytoma, ganglioglioma 3, 12 and ependymoma (11). While most areas of the present tumor show features compatible with a “low‐grade” glioma, focal regions with elevated Ki67 labeling index up to 20% (Fig 1C) was worrisome for focal anaplasia. Since oligodendroglioma and mixed oligoastrocytoma are relatively rare in pediatric patients, there is currently no consensus or guidelines on how to treat these tumors. The rapidly deteriorating clinical course, unfortunately, attests to the anaplastic nature of this tumor, with striking parallel to a recently reported case (6).

In conclusion, although most pediatric tectal gliomas are low grade tumors that can be managed conservatively, the present case as well as those in previous reports 3, 6, 11, 12 show that some of these tectal gliomas can have anaplastic features with aggressive clinical course. The development of effective chemotherapy and radiation therapy strategies will be crucial in the future management of these tumors, if they cannot be totally resected surgically.

ABSTRACT

With rare exceptions, pediatric tectal gliomas have been generally reported as low‐grade tumors with relatively good prognosis. The patients are usually treated conservatively to manage the signs and symptoms of obstructive hydrocephalus. We report a case of a tectal glioma in a 6‐years‐old girl with histological features of anaplastic mixed oligoastrocytoma that continues to progress despite chemotherapy and radiation therapy.