Case
Awoman in her 30s presented with a 1-year medical history of a painless, slowly enlarging, midline neck mass without associated dysphagia, odynophagia, weight loss, or history of infection. The mass was soft, mobile, and compressible in midline level IA, measuring 7 cm and posterior-superiorly displacing the tongue. The mass was visible as a clear blue lesion in the floor of the mouth and was nontender. Computed tomographic (CT) scan of the neck with IV contrast was performed (Figure). The patient was taken to the operating room for a successful combined intraoral and transcervical approach to excision.
Figure.
Computed tomographic images. A, Coronal view of midline neck mass. B, Sagittal view of midline neck mass.
What Is Your Diagnosis?
- Simple ranula
- Epidermoid cyst
- Vascular malformation
- Odontogenic abscess
Discussion
Diagnosis
B. Epidermoid cyst
Epidermoid cysts (ECs) are classically small, benign, cystic masses with 32% of lesions occurring in the head and neck.1 They usually arise because of failure of primitive epithelial cells to separate from underlying deep tissue during branchial arch formation.2 True ECs are fluid-filled lesions lined by simple squamous epithelium and a layer of keratin. They have been referred to by other terms such as epidermal cysts, epidermal inclusion cysts, sebaceous cysts, and seborrheic cysts. However, the terms “seborrheic cysts” and “sebaceous cysts” are misnomers, not synonymous with epidermoid cysts. Epidermoid cysts are normally close to the skin and can be located anywhere on the face, scalp, and neck. However, in the deep tissue planes, ECs in the head and neck make up only 1.6% to 6.9% of cases in the entire body.3
The typical presentation of an EC is a soft, slow-growing, nontender mass without fixation to underlying tissues. Epidermoid cysts frequently do not cause symptoms and go unnoticed until they reach a large size or become infected.4 Obstructive symptoms like dysphagia, odynophagia, dysphonia, and dyspnea are more typical for lesions above the mylohyoid because this results in superior displacement of the tongue. In contrast, masses below the mylohyoid cause protrusion into the chin in the front of the neck, giving rise to the characteristic double chin appearance.5,6 In this case, the cyst was quite large, measuring over 8 cm in greatest dimension, but it produced no obstructive symptoms.
Both benign and malignant neoplasms may present as cystic lesions in the floor of mouth.7However, malignant disease is generally limited to necrotic squamous cell carcinoma lymphadenopathy. These lesions generally are thick-walled and found in the submandibular space, which is inconsistent with the sublingual lesion described herein. Venous malformations may also present as cystic masses in the neck with the presence of phleboliths as the characteristic imaging finding.8 Arteriovenous malformations may be visualized as high-flow lesions with multiple tortuous channels.8 The absence of characteristic imaging findings excludes vascular malformation as a viable consideration in this case.
On CT scan, ECs are described as unilocular masses, and ranulas appear as well-circumscribed, lobulated cystic lesions with central homogeneous low CT attenuation.8 However, not all lesions present with these characteristic radiologic signs. Indeed, Coit et al7 note that ECs cannot be absolutely distinguished from ranulas by radiographic means alone. In this case, initial imaging and physical examination findings were more consistent with a ranula than an EC. The mass had a bluish coloration on examination, which is a common feature of ranulas. Findings of the CT scan showed a cystic, homogenous mass without hypoattenuating fat nodules, calcifications, or septations contained in the floor of the mouth and sublingual space, increasing our suspicion of a ranula. We initially planned for intraoral marsupialization with sublingual gland excision. However, working diagnosis was intraoperatively changed to dermoid cyst vs EC owing to thick cyst wall. The decision was made to completely excise the mass leaving the sublingual gland. Final pathologic diagnosis confirmed EC.
Although inflamed ECs without infection may be treated with intralesional steroids alone, complete surgical excision or enucleation is regarded as the definitive treatment of choice.4Recurrence after total excision is rare.9 Giant ECs greater than 5 cm are uncommon, and few cases in the head and neck have been reported.10 Herein we present a case of a giant deep tissue EC mimicking a simple ranula, serving as a reminder to include EC in the differential for cystic masses of the floor of mouth or midline of the neck.
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Article Information
Published Online: April 11, 2019. doi:10.1001/jamaoto.2019.0320
Conflict of Interest Disclosures: None reported.
Additional Contributions: We thank the patient for granting permission to publish this information.
References
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