Neuro / Head & Neck for Wednesday, June 3rd, 2026

Contributed by Marmara University Pendik Training and Research Hospital
Omer Faruk DOMRUK, and Nuri Cagatay Cimsit.

History

A 5-year-old girl presented with intermittent right-sided facial swelling since birth, with exacerbations during upper respiratory tract infections. Physical examination revealed right parotid swelling and bilateral cervical lymphadenopathy.

Images (Click any image to enlarge)

STIR axial
STIR coronal
T1 axial pre-contrast
DWI
ADC
T1 axial post-contrast

Question

Q1: What is the most likely diagnosis?

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Correct answer

Lymphatic malformation

Discussion

A 5-year-old girl presented with intermittent right-sided facial swelling since birth, with exacerbations during upper respiratory tract infections. Physical examination revealed right parotid swelling and bilateral cervical lymphadenopathy.

Cystic lesions of the pediatric parotid gland include congenital, inflammatory, and vascular entities [1,2]. This case illustrates a diagnostic challenge due to overlapping imaging features and superimposed inflammatory changes.

The patient had right facial swelling since birth, with exacerbations during upper respiratory tract infections, suggesting an underlying congenital lesion. Initial imaging demonstrated multiloculated cystic lesions centered in the right parotid space. MRI showed fluid–fluid levels, foci of T1 hyperintensity, and diffusion restriction, along with cervical lymphadenopathy, raising concern for an infected branchial cleft cyst or abscess. Enlarged level IIA lymph nodes (short axis up to 10 mm) were also present, consistent with reactive lymphadenopathy in the setting of concurrent infection. No solid enhancement was identified on post-contrast imaging, and the lesion demonstrated trans-spatial extension toward subcutaneous and temporal regions.

However, these findings can be explained by inflammatory complication of a pre-existing lymphatic malformation [3,4]. Reactive lymphadenopathy and acute clinical symptoms further support a secondary inflammatory process rather than a primary localized infection. Additionally, extension into the retropharyngeal and parapharyngeal spaces indicates a trans-spatial process rather than a well-circumscribed cystic lesion. A venous malformation is less likely given the absence of progressive or delayed enhancement and the predominantly cystic, multiloculated morphology.

Although diffusion restriction and fluid–fluid levels may suggest abscess, the absence of a thick enhancing wall, lack of a discrete drainable collection, trans-spatial infiltrative pattern, and interval resolution of diffusion restriction without complete lesion resolution argue against a primary abscess and favor a complicated lymphatic malformation [1].

First branchial cleft cyst is also less likely, as these lesions are typically well-circumscribed, localized, and do not demonstrate extensive trans-spatial spread or infiltrative behavior.

Follow-up MRI demonstrated:

  • Resolution of diffusion restriction

  • Disappearance of fluid–fluid levels

  • Persistent multiloculated cystic architecture

  • Mild interval decrease in lesion size

This evolution is characteristic of lymphatic malformations, which may transiently mimic abscess when complicated by inflammation or hemorrhage [3,5]. Similar imaging features, including fluid–fluid levels, may also be seen in lymphaticovenous malformations; however, the lack of enhancement and absence of identifiable venous components favor a pure lymphatic malformation in this case [1]. The presence of trans-spatial spread across fascial planes, including retropharyngeal and parapharyngeal involvement, is a key imaging feature supporting this diagnosis [3].

Fine needle aspiration biopsy (FNAB), performed with delay due to parental preference, was non-specific. This is consistent with the known limitations of FNAB in cystic lesions, where low cellularity and fluid sampling frequently result in non-diagnostic findings and may not reflect the underlying pathology [6].

Overall, the congenital onset, infection-related exacerbations, imaging evolution, and trans-spatial distribution strongly support the diagnosis of lymphatic malformation with prior inflammatory/infectious complication.

Differential diagnosis

  • Lymphatic malformation

  • First branchial cleft cyst

  • Venous malformation

  • Infantile hemangioma

  • Parotid abscess

  • Sialocele / ductal cyst

Additional images

Fig. 1: Axial T2-weighted (STIR) MRI shows a multiloculated, markedly T2-hyperintense trans-spatial cystic lesion centered in the right parotid space, involving the parotid gland (thick arrow) and extending into the parapharyngeal and retropharyngeal spaces (arrowhead and thin arrow, respectively), with partial subcutaneous extension toward the right temporal region (not demonstrated)
Fig. 2: Coronal T2-weighted MRI (STIR) demonstrates the retropharyngeal (thin arrow) and right parapharyngeal (thick arrow) components of the lesion, which appears multiloculated with multiple septations and markedly T2 hyperintense.
Fig. 3: Axial fat-saturated T1-weighted MRI at the level of the deep lobe of the right parotid gland shows corresponding T1 hyperintensity in the area of diffusion restriction (thick arrow).
Fig. 4: Axial DWI (a) and ADC maps demonstrate a fluid–fluid level within the lesion, with the dependent component appearing hyperintense on DWI and markedly hypointense on ADC, consistent with diffusion restriction (thick arrows).
Fig. 5: Axial post-contrast fat-saturated T1-weighted MRI demonstrates no enhancement within the lesion, while the remaining right parotid gland shows normal parenchymal enhancement (thick arrow).
Fig. 6: Axial fat-suppressed T2-weighted MRI at 2-year follow-up demonstrates a relative interval decrease in lesion size (thick arrow), particularly in the parapharyngeal (arrowhead) and retropharyngeal (thin arrow) components.
Fig. 7: On 2-year follow-up DWI and ADC maps, the previously noted diffusion-restricting component is no longer identified.

References

  • 1. Friedman ER, John SD. Imaging of pediatric neck masses. Radiol Clin North Am. 2011;49(4):703–726. doi:10.1016/j.rcl.2011.05.005.
  • 2. Ahuja AT, King AD, Metreweli C. Second branchial cleft cysts: variability of sonographic appearances. AJNR Am J Neuroradiol. 2000;21(2):315–319.
  • 3. Flors L, Leiva-Salinas C, Maged IM, et al. MR imaging of soft-tissue vascular malformations: diagnosis, classification, and therapy follow-up. Radiographics. 2011;31(5):1321–1340.
  • 4. Adams MT, Saltzman B, Perkins JA. Head and neck lymphatic malformations: a review of current treatment and imaging. Otolaryngol Clin North Am. 2018;51(1):147–166.
  • 5. Kennedy TL, Whitaker M, Pellitteri P, Wood WE. Cystic hygroma/lymphangioma: a rational approach to management. Laryngoscope. 2001;111(11):1929–1937.
  • 6. Layfield LJ, Glasgow BJ. Fine-needle aspiration in the diagnosis of head and neck lesions. Diagn Cytopathol. 1993;9(6):634–650.