Encephalocele with an area mimicking giant cell fibroblastoma. Case report.

We report a unique case of encephalocele with an area mimicking giant cell fibroblastoma. A 4-month-old boy had been born with a parietal midline mass of the head, measuring 3x3x1.5 cm. Microscopically, it consisted of fibrous connective tissue and brain tissue. The fibrous tissue revealed spindle cells and multinucleated giant cells lining sinusoid-like spaces. This area was reminiscent of giant cell fibroblastoma. These cells were immunopositive for vimentin and negative for CD34. The giant cell fibroblastoma-like lesion in our case seems to be non-neoplastic and hamartomatous, and we think that the immunohistochemistry using CD34 is useful for differentiating the two lesions.