RARE-10SYLVIAN FISSURE DERMOID CYST WITH GIANT CELL REACTIVITY: A REPORT OF A RARE CASE AND REVIEW OF THE LITERATURE

Abstract

INTRODUCTION: Dermoid cysts are rare intracranial tumors that are most commonly found infratentorially and along the midline. These benign lesions, which are the result of defective closure of neuroectodermal folds containing mesenchymal elements, are usually discovered in late childhood or early adulthood. Characterized by slow growth and often found incidentally, these lesions can nonetheless have severe complications, notably rupture leading to chemical meningitis. They infrequently present as a supratentorial and lateralized mass. As such, Sylvian fissure dermoid cysts are exquisitely rare. To the best of our knowledge, there are 11 prior reported cases of Sylvian fissure dermoid cysts. We present a rare case of a dermoid cyst with giant cell reactivity suggestive of focal rupture and chronic inflammation. CASE: A 61 year-old female who presented with new onset seizures was seen at our institution. On physical examination she was neurologically intact. Magnetic resonance imaging revealed a right insular mass measuring 4.3x4.5cm with compression of the ipsilateral frontal and temporal lobe. The mass was non-enhancing; however it was bright on diffusion-weighted imaging, suggesting a dermoid cyst. She underwent craniotomy for tumor resection. Histological analysis revealed keratinizing squamous epithelium, rare sebaceous glands and hair follicles consisted with dermoid cyst. There was also an associated giant cell reaction involving the fibrous capsule of the cyst. At 18-months post-operative, she is seizure free and without evidence of recurrence. CONCLUSION: The dermoid cyst in our patient was not grossly ruptured, however histopathological analysis revealed giant cell reactivity indicating focal rupture. The relationship between rupture of dermoid cysts and inflammation is not well elucidated. It is not known whether symptoms occur immediately after rupture or as an acute manifestation of a chronic process following rupture. As these lesions and their rupture are quite rare, more diligence regarding details of histopathology for dermoid cysts is needed.