Taro Mikami1,2, Chie Maeda3, Fumihiko Aoki4, Toshinori Iwai5, Yuichiro Yabuki6, Tetsuhiko Okabe7, Kenichi Ohashi8, Jiro Maegawa6. 1. Department of Plastic and Reconstructive Surgery, Yokohama City University Graduate School of Medicine, Fukuura 3-9, Kanazawa-ku, Yokohama, Kanagawa, 236-004, Japan. zeong3@mac.com. 2. Department of Plastic and Reconstructive Surgery, Chigasaki Municipal Hospital, Honson 5-15-1, Chigasaki, Kanagawa, 253-0042, Japan. zeong3@mac.com. 3. Department of Plastic and Reconstructive Surgery, Fujisawa-Shounandai Hospital, Takakura 2345, Fujisawa, Kanagawa, 252-0802, Japan. 4. Shonandai AOKI Plastic Surgery Clinic, Shonandai 2-10-7, Fujisawa, Kanagawa, 252-0804, Japan. 5. Department of Oral and Maxillofacial Surgery, Yokohama City University Graduate School of Medicine, Yokohama, 236-004, Japan. 6. Department of Plastic and Reconstructive Surgery, Yokohama City University Graduate School of Medicine, Fukuura 3-9, Kanazawa-ku, Yokohama, Kanagawa, 236-004, Japan. 7. Department of Radiology, Yokohama City University School of Medicine, Fukuura 3-9, Kanazawa-ku, Yokohama, Kanagawa, 236-004, Japan. 8. Department of Pathology, Yokohama City University Graduate School of Medicine, Fukuura 3-9, Kanazawa-ku, Yokohama, Kanagawa, 236-004, Japan.
Abstract
BACKGROUND: Dermoid cysts are well-known lesions that manifest as subcutaneous tumors around the lateral sides of the eyebrows in young patients. Computed tomography or magnetic resonance imaging (MRI) is often performed to confirm the diagnosis. On the other hand, a lipoma is usually a circular lesion, which is sometimes observed in the upper part of the face. The signals of both T1-weighted and T2-weighted images of MRI of a lipoma are, in general, relatively highly homogenous, and the signals decrease in fat-suppressed images. Therefore, differential diagnosis between a dermoid cyst and a lipoma is usually made with MRI, especially based on fat-suppressed images. Here, we present a case of misdiagnosis of a dermoid cyst as a lipoma because of atypical magnetic resonance images. CASE PRESENTATION: We report a case of a 24-year-old Japanese woman with a dermoid cyst around the lateral edge of the eyebrow. The cyst had been gradually increasing in size for the past 2 years. On MRI, it showed high internal signals on T1- and T2-weighted images. However, the signal intensity decreased homogeneously in the fat-suppressed T2-weighted images. The observed tumor had a yellowish appearance under the endoscope. On the basis of these findings, the lesion was considered a lipoma until it ruptured intraoperatively. The pathological diagnosis confirmed it to be a dermoid cyst. CONCLUSION: Some dermoid cysts contain lipid-rich liquid, and these may be misdiagnosed as lipomas by MRI. When a tumor is located at a common site for a dermoid cyst, the MRI images should be validated carefully if it appears like a lipoma, and the differential diagnosis should be considered carefully.
BACKGROUND: Dermoid cysts are well-known lesions that manifest as subcutaneous tumors around the lateral sides of the eyebrows in young patients. Computed tomography or magnetic resonance imaging (MRI) is often performed to confirm the diagnosis. On the other hand, a lipoma is usually a circular lesion, which is sometimes observed in the upper part of the face. The signals of both T1-weighted and T2-weighted images of MRI of a lipoma are, in general, relatively highly homogenous, and the signals decrease in fat-suppressed images. Therefore, differential diagnosis between a dermoid cyst and a lipoma is usually made with MRI, especially based on fat-suppressed images. Here, we present a case of misdiagnosis of a dermoid cyst as a lipoma because of atypical magnetic resonance images. CASE PRESENTATION: We report a case of a 24-year-old Japanese woman with a dermoid cyst around the lateral edge of the eyebrow. The cyst had been gradually increasing in size for the past 2 years. On MRI, it showed high internal signals on T1- and T2-weighted images. However, the signal intensity decreased homogeneously in the fat-suppressed T2-weighted images. The observed tumor had a yellowish appearance under the endoscope. On the basis of these findings, the lesion was considered a lipoma until it ruptured intraoperatively. The pathological diagnosis confirmed it to be a dermoid cyst. CONCLUSION: Some dermoid cysts contain lipid-rich liquid, and these may be misdiagnosed as lipomas by MRI. When a tumor is located at a common site for a dermoid cyst, the MRI images should be validated carefully if it appears like a lipoma, and the differential diagnosis should be considered carefully.