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Neuroradiology Case of the Week
Case 384
February 2009
Charles Hubeny, MD
Clinical
Presentation: A 12-year-old presented with painless swelling in floor of mouth. Dentition is intact and there are no signs of infection.
Imaging Findings: MR demonstrated a well-circumscribed ovoid shaped mass in the midline of the tongue, bright on T2 and intermediate on T1.
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| Figure 1: T1-weighted MR image in coronal plane demonstrates an oblong mass with slightly higher signal than that compared to skeletal muscle. |
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| Figure 2: The mass shows high signal on a coronal STIR image. |
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Figure 3. |
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Figures 3 & 4: Axial and coronal T2 weighted image show the well circumscribed midline mass within the tongue. |
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| Figure 5: A gross picture of the excised tumor which was proven to be a dermoid. |
Diagnosis: Dermoid tumor of the tongue
Discussion: Epidermoid and dermoid cysts are benign tumors and represent less than 0.01% of all oral cavity cysts. They occur throughout the body with 7% of these tumors arising in the head and neck and 1.6% specifically in the oral cavity. Dermoid cysts are defined by the presence of skin appendages such as hair follicles, hair, and apocrine/eccrine sweat glands while epidermoid cysts have simple squamous epithelium without skin appendages.
The anterior tongue is formed from two opposite lateral swellings arising from the first branchial arch during weeks three to five of embryological development. Lingual dermoids develop from epithelial rests that are trapped during the union of lateral lingual swellings during medial migration. For this reason the tumor is usually midline.
Imaging characteristics of dermoid tumors include rounded or lobulated cystic masses of variable size and of fat attenuation on CT. Twenty percent have calcium. On MRI dermoids usually show higher intensities on T1 weighted imaging but can be heterogeneous as the tumor may contain elements other than fat. Signal suppression with fat saturation technique is diagnostic. T2-weighted imaging may range from hyper- to hypointense. A rare solid dermoid can be very hypointense on T2. Dermoids typically do not enhance.
Differential diagnosis for midline tongue lesions include thyroglossal duct cysts, mucous retention cysts, teratoma, epidermoid cysts, or lingual thyroid tissue.
Recommend management is usually surgical excision. The likelihood of recurrence is presumed to be low although a sublingual dermoid is such a rare tumor that there is no long-term follow-up data. Drainage procedures are generally not used as they can cause implantation of the tumor along the drainage path.
Prognosis is good as nearly all reported tumors are benign but there has been a case reported with malignant transformation.
References:
- Shaari CM, Ho BT, Shah K, Biller HF. Lingual dermoid cyst. Otolaryngol Head Neck Surg. 1995 Mar;112(3):476-8. [PubMed]
- Milam M, Hill SA, Manaligod JM. Lingual dermoid cysts. Otolaryngol Head Neck Surg. 2003 Mar;128(3):428-9. [PubMed]
- Kandogan T, Koç M, Vardar E, Selek E, Sezgin O. Sublingual epidermoid cyst: a case report. J Med Case Reports. 2007 Sep 17;1:87. [PubMed]
- Devine JC, Jones DC. Carcinomatous transformation of a sublingual dermoid cyst. A case report. Int J Oral Maxillofac Surg. 2000 Apr;29(2):126-7. [PubMed]
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