Imaging characteristics of primary intracranial teratoma

Background: Primary intracranial teratomas are rare intracranial neoplasms, and are subdivided into mature, immature, and those with malignant transformation. To date, only a few studies of teratoma imaging have been reported. Purpose: To describe and characterize the magnetic resonance imaging (MRI) findings in a series of 18 patients (16 men/boys and 2 women/girls; mean age, 14.5 years) with pathologically proven teratomas. Material and Methods: Findings from medical records and imaging examinations in 18 patients with pathologically confirmed intracranial teratomas from 2001 to 2011 were retrospectively reviewed at our two institutions. Two radiologists evaluated the lesion location, shape, size, number, edge, homogeneous or heterogeneous appearance, attenuation, signal intensity, and degree of enhancement. Results: All tumors were located within the pineal (n = 13), parasellar (n = 2), or suprasellar (n = 3) regions. The lesions appeared of mixed intensity on MRI, reflecting the histologic heterogeneity, including fibrosis, fatty tissue, calcification, cysts, and keratinocytes. In mature teratomas (n = 9), seven of nine tumors showed non-enhanced multilocularity or heterogeneous enhancement of the cyst wall on contrast-enhanced T1-weighted (T1W) images. Two of nine tumors showed moderate, heterogeneous enhancement in the solid portion of the lesion; whereas in immature (n = 7) or malignant transformation (n = 2) teratomas, heterogeneous, ring-like, intratumoral patchy enhancement was noted on T1W images with contrast. Conclusion: Primary intracranial teratomas are usually localized in the pineal and the suprasellar regions, and often present an ovoid or lobulated mass with or without multilocularity on MRI. Marked enhancement of the solid portion or the thick wall of the tumor was the key feature for distinguishing mature teratoma and malignant teratoma.