Intracranial dermoid cysts are rare congenital lesions that result from abnormal sequestration of ectodermal cells during neural tube formation. These tumors are especially rare in lateral areas such as in the temporal lobe. In this study, we report a case of dermoid cyst located in the right temporal lobe. A 50-year-old man was referred for further treatment of a tumor. CT revealed a low-density mass lesion in the right temporal lobe, with calcification. MRI showed the lesion with high signal intensity on diffusion-weighted imaging, high-low mixed signal intensity on T1-weighted imaging, and iso-high signal mixed intensity on T2-weighted imaging; the capsule was enhanced with gadolinium. Differential diagnosis included dermoid cyst, epidermoid cyst, teratoma, and neurenteric cyst. We decided to perform surgery for the improvement of his symptom, histopathological diagnosis, and radical cure. A right temporal craniotomy was performed, and the tumor was found adherent to the surrounding brain tissue. The tumor was completely removed under subpial dissection. Hair was confirmed in the tumor content. On histopathology, the cyst wall was lined with stratified squamous epithelium, sebaceous glands, small vessel aggregates, and inflammatory infiltrate. Keratinized material and hair were found in the lumen. The patient was discharged 7 days after surgery with no new neurologic deficits. This case was unusual in terms of the effect of gadolinium enhancement on MRI, and the presence of adipose tissue and calcification were useful for diagnosis. It is vital to consider prevention of chemical meningitis due to intrathecal dissemination of the tumor content intraoperatively.
Keywords: MRI; dermoid cyst; temporal lobe.
© 2021 The Japan Neurosurgical Society.