Contributed by Erin M. Chapman3, Adrianna Ranger, MD1,4, Donald H. Lee, MD2, Robert R. Hammond1,3, MD
Departments of Clinical Neurologic Sciences1, Diagnostic Radiology and Nuclear Medicine Radiology2, Pathology3 and Pediatrics4
London Health Sciences Center and Schulich School of Medicine and Dentistry, London, Ontario, Canada
A 15 year old boy presented to our center with progressive headache, vomiting, gait instability and reduced visual acuity of one month's duration. The patient related a head injury as a result of a fall while playing hockey as coinciding with the onset of his symptoms but no other significant history. Physical examination revealed severe bilateral papilledema.
CT demonstrated marked hydrocephalus involving the lateral and third ventricles. T2 (Figure 1) and FLAIR (Figure 2) MRI revealed the inferior tectum, aqueduct and superior fourth ventricle to be obliterated by a 1.6 x 1.8 x 2 cm mass and associated 2 x 2 x 2.5 cm cyst. The solid portion displayed minimal enhancement (Figure 3 pre-gadolinium; Figures 4, 5 and 6, post-gadolinium). Imaging features favored an ependymoma or low grade astrocytoma.
Surgical excision of the mass found it to be obstructing the sylvian aqueduct. The grey to tan colored fleshy mass was completely resected from the ventricular system and sent for pathological examination.
Microscopic examination of the resected tumor revealed a highly pleomorphic and fibrillary lesion (Figures 7 and 8). Lesional cells varied from pilar to multipolar to giant with multiple and pleomorphic nuclei. Many tumor cells had prominent cytoplasmic vacuolation and/or fine granular brown pigment (Figure 8). Perivascular lymphocytes and sparse eosinophilic granular bodies were present. No mitotic activity, endothelial hyperplasia or necrosis were seen.
The granular brown cytoplasmic pigment stained black with Masson-Fontana preparation (Figure 9). Gomori and Sweet's reticulin stain revealed generous reticulin surrounding individual cells or groups of cells (Figure 10). The neoplastic cells expressed abundant GFAP (Figure 11) and select cells lightly coexpressed synaptophysin and neurofilament. Ki-67 labeling was sparse (below 1% in 10 random fields).
Ultrastructural studies confirmed the presence of melanosomes within the tumor cells (Figure 12).