Posttraumatic Sialocele of the Submandibular Gland
- Background:
- Injury to the salivary glands is rare, with parotid injury being more common than sublingual or submandibular injury, and usually secondary to penetrating trauma, although blunt traumatic and iatrogenic etiologies have also been described.
- Sialoceles are one of the complications of salivary gland injury, defined as accumulations of saliva that cannot adequately drain into the oral cavity.
- Virtually all reported sialoceles are in the parotid region; submandibular sialoceles are extremely uncommon.
- Clinical Presentation:
- Posttraumatic sialoceles generally present as a soft, fluctuant mass without tenderness on palpation days to months after the initial injury.
- Patients are generally afebrile and regional cellulitis is not evident.
- Key Diagnostic Features:
- By imaging, sialoceles are well-marginated, oval, fluid collections intimately associated with the salivary gland.
- CT features include a low-attenuation collection with thin or imperceptible walls centered within or adjacent to the salivary glands. The gland itself is of normal attenuation without significant surrounding inflammatory change.
- MRI features include a T2-bright, nonenhancing or thinly rim-enhancing structure adjacent to or within the salivary gland, generally without active inflammation of the gland or regional tissues and without internal restricted diffusion.
- Superinfection can complicate their appearance, creating a multiloculated appearance with thickened walls, sialadenitis, and surrounding stranding.
- Salivary amylase is elevated in sialoceles of the predominantly serous-secreting parotid gland and can be elevated in the serous- and mucous-producing submandibular gland; fluid culture is generally negative or scant.
- Differential Diagnoses:
- Salivary gland abscess: Thick-walled, heterogeneous collections associated with an enlarged, inflamed salivary gland, regional fat stranding, fascial thickening, and effacement of fat planes; internal restricted diffusion can be present on MRI in bacterial abscesses.
- Ranula: A postinflammatory or posttraumatic mucous retention cyst of the sublingual gland (a primarily mucous-secreting rather than serous-secreting gland) or minor salivary glands; plunging ranulas can extend posteriorly beyond the free edge of the mylohyoid into the submandibular space or through congenital defects in the mylohyoid into the submental space; these are well-marginated, thin-walled cysts in the sublingual and/or submandibular spaces that can demonstrate T1 shortening if proteinaceous, but without internal complexity or enhancement unless superinfected.
- Cystic tumors: Benign (eg, Warthin tumor, pleomorphic adenoma) or low-grade malignant (eg, mucoepidermoid carcinoma, adenoid cystic carcinoma) salivary gland tumors can present as cystic lesions with or without enhancement. Pleomorphic adenomas can be T2 bright and enhance. Warthin tumors can occasionally demonstrate restricted diffusion. Perineural spread is most common in adenoid cystic carcinomas and is reflected by abnormal thickening and nodularity along regional nerves.
- Dermoid/epidermoid: Cystic lesions that can occur in the head and neck; dermoid cysts can demonstrate T1 shortening reflecting fatty elements, and epidermoid cysts classically demonstrate restricted diffusion; walls are thin or imperceptible; regional inflammation is not present; dermoids are more common in the submandibular space and epidermoids in the floor of the mouth.
- Lymphatic malformation: Single or multispatial, T2-bright, nonenhancing cystic lesions without restricted diffusion; these can contain fluid-fluid levels and septations.
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Treatment:
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Acute sialoceles may require primary closure of the lacerated gland or duct (more common approaches for the parotid gland) or resection of the gland (more common for the submandibular gland).
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Delayed sialoceles generally heal with conservative treatment consisting most commonly of pressure dressings, serial aspirations, and sialogogues. Other options include injection of botulinum toxin or radiotherapy in refractory cases.
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