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Neuroradiology Case of the Week
Case 396
March 2009
Yasser Elshatory, Balasubramanya Kolar, MD,
and PL Westesson, MD, PhD, DDS
Clinical
Presentation: Patient is a three-month-old male undergoing evaluation for a neck mass that has been increasing in size. No note of the mass was made at birth or at one month of age.
Imaging Findings: Large, well-circumscribed mass in the left parotid space with prominent vascular channels. T2-weighted MR images revealed a mass that was uniformly hyperintense except for low-signal flow voids within the mass consistent with blood vessels. Homogenous, intense contrast-enhancement was also observed.
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| Figure 1: Axial T2-weighted fat-saturated image shows predominantly hyperintense lesion in left parotid region with flow voids. |
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| Figure 2: Axial T1-weighted image shows isointense mass lesion with flow voids in left parotid space. |
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| Figure 3: Axial post-contrast T1-weighted fat-suppressed image shows homogenous intense enhancement of the mass. |
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| Figure 4: Coronal post-contrast T1-weighted image shows the enhancing mass in left parotid region. |
Diagnosis: Hemangioma of the left parotid
Discussion: The differential diagnosis for masses within the parotid space should include benign and malignant diseases that arise from the limited contents of this area, which include the parotid gland, cranial nerve VII and lymph nodes. Confirmation that the mass arises from the parotid space and not other adjacent locations can be made by studying the disposition of fat contained within the parapharyngeal space, which is situated anteromedially to the parotid space. Therefore, enlargement of the parotid space should coincide with a shift in the fat within the parapharyngeal space anteromedially, whereas enlargement of the adjacent mastoid space secondary to a rhabdomyosarcoma, for example, would lead to a posteromedial displacement of the parapharyngeal space.
Arising from the parotid, both epithelial-derived tumors, such as pleomorphic adenoma, Warthin tumor, intraductal papilloma, and oncocytoma, as well as non-epithelial-derived tumors, such as hemangioma, lymphangioma and lipoma, can present with parotid space enlargement. Also, lymphoma and metastatic diseases to the lymph nodes should be ruled out when necessary, as should schwannomas and neurofibromas of the facial nerve.
Imaging with MR and CT can occasionally reveal the type of neoplasm definitively, but only for certain cases, such as lipomas of the parotid gland. History helps narrow the likely etiology. Among the most common salivary gland tumors of children, for example, are hemangiomas and lymphangiomas. In our case, the prominent vascularity is suggestive of hemangioma, as is the reported increase in size related by the parents. Hemangiomas, after a period of proliferation and expansion, often undergo spontaneous involution but this may take several years to occur. Furthermore, certain large hemangiomas can have serious consequences, such as bleeding and heart failure, and may also result in a permanent cosmetic defect prior to involution, such as stretching of the skin overlying the hemangioma. Intralesional injection of steroids can in such cases result in dramatic reduction of hemangioma size.
References:
- Chahin F, Kaufman MR. Salivary gland tumors, minor, benign. eMedicine. April 15, 2008. http://emedicine.medscape.com/article/194522-overview.
- Chong VF, Fan YF. Radiology of the parapharyngeal space. Australas Radiol. 1998 Aug;42(3):278-83. [PubMed]
- Hanna EY, Lee S, Fan CU, Suen JY. Chapter 60 - Benign neoplasms of the salivary glands. IN: Cummings CW, Flint PF, Haughey BH, et al., eds. Cummings: Otolaryngology: Head & Neck Surgery, 4th ed. Mosby, 2005. [MDConsult]
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