Atypical MRI and Histopathological Findings in Dermoid Cyst

• Published in: Bulletin of Tokyo Dental College Vol. 59; no. 3; pp. 207 - 212
• Main Authors: Otonari-Yamamoto, Mika, Nakajima, Kei, Sakamoto, Junichiro, Imoto, Kenichi, Watanabe, Motoko, Kotaki, Shinya, Kuroda, Migiwa, Matsuzaka, Kenichi, Shibahara, Takahiko, Curtin, Hugh D., Goto, Tazuko K.
• Format: Journal Article
• Language: English
• Published: Japan Tokyo Dental College, Japan 01.01.2018; Japan Science and Technology Agency
• Subjects: Computed tomography; Cysts; Dentistry; Dermoid cyst; Dermoid Cyst - diagnostic imaging; Dermoid Cyst - pathology; Diagnosis; Diffusion weighted imaging (DWI); Female; Floor of the mouth; Humans; Ions; Keratin; Lipoma; Magnetic Resonance Imaging; Magnetic resonance imaging (MRI); Middle Aged; Mouth Floor - diagnostic imaging; Mouth Neoplasms - diagnostic imaging; Mouth Neoplasms - pathology; NMR; Nodules; Nuclear magnetic resonance; Sebaceous gland; Dermoid cyst; Magnetic resonance imaging (MRI); Floor of the mouth; Diffusion weighted imaging (DWI)
• ISSN: 0040-8891
• DOI: 10.2209/tdcpublication.2017-0044

On images, a dermoid cyst is often described as resembling a “sack of marbles” or “marbles in a bag”. Typically, it comprises an inhomogeneity filled with multiple nodules in a fluid matrix on both computed tomography and magnetic resonance imaging (MRI). How it appears, however, will vary depending on its histological contents, which may cause confusion in arriving at a diagnosis. This report describes a dermoid cyst in the floor of the mouth of a 55 year-old woman that showed an atypical internal appearance on MRI. Most of the lesion showed homogeneous high signal intensity on T1 - and T2-weighted images, suggesting that it was derived from fat. A small area within the mass, however, showed moderate signal intensity almost equal to that of muscle on T1-weighted images and high signal intensity on fat-suppressed T2-weighted images. Given the location of the lesion, a dermoid cyst was one possible diagnosis. A lipoma or lipoma variants were also considered, however, based on signal intensity. Histopathological section of the excised specimen revealed a dermoid cyst with sebaceous glands in its walls and keratin in its cavity. Dermoid cysts show variation in their internal structures and contents. Since MRI can reflect such histological variation, signal intensity requires careful interpretation.