Deep lobe pleomorphic adenoma

Case contributed by H&N spaces

Presentation

3 month history of left facial pain with tenderness over the left submandibular region

Patient Data

Age: 40
Gender: Female
Modality: MRI

Mass in the deep lobe of the left parotid gland measuring 3 x 2.9 x 2.7 cm.

The mass has lobulated margins and is very bright on T2-weighted imaging.

The mass demonstrates low to intermediate signal on T1-weighted imaging patchy central enhancement post contrast and raised ADC values. There is mild remodelling of the inner surface of the left mandibular ramus. No evidence of abnormal enhancement along the left facial nerve.

No evidence of a right parotid lesion. No pathologically enlarged lymph nodes are seen.

Conclusion:

Left parotid lesion within the deep lobe, likely representing a pleomorphic adenoma.

Modality: CT

NECK:
A 3.0 x 3.0 x 2.7 cm low attenuation mass is present within the deep lobe of the left parotid gland showing faint to moderate central irregular curvilinear and minor rim enhancement. It medially abuts the carotid artery, oropharyngeal muscles and effaces the parapharyngeal fat.  It posteriorly contacts the jugular vein with no evidence of venous thrombosis.

The lesion laterally abuts the left mandibular ramus and there is evidence of pressure erosion of the mid-portion of posterior aspect of the medial cortical bone. Likely enlarging but not eroding the orifice of mandibular canal of the inferior alveolar nerve. The mass is epicentred between the medial and lateral pterygoid muscles. No skull base contact skull. No cervical nodal disease. The appearances are typical of a long-standing salivary gland pleomorphic adenoma.

CHEST:
Lungs are clear. No associated emphysema or bronchitis. No lung nodulation, pleural or pericardial effusion. No intrathoracic or visible axillary adenopathy.
The upper abdominal parenchymal organs are unremarkable. No adrenal nodulation, splenic lesion or visualised liver abnormality. Incidental note is made of a small rounded low attenuation left upper pole renal cortical cyst.

No erosive bone lesion is noted in the neck and chest wall.

CONCLUSION:
Left deep parotid space / parapharyngeal mass, compressing but not invading adjacent structures.
Differentials include benign and malignant salivary gland /parapharyngeal tumours.

Histology

MACROSCOPIC DESCRIPTION:

Parapharyngeal mass and parotid margins: Multiple rubbery, yellow tan tissue fragments, in aggregate 50x40x15mm.

MICROSCOPIC DESCRIPTION:

Sections show multiple fragments of parotid tissue and tumour. Parapharyngeal tissue has a bimorphic morphology with prominent areas of chondromyxoid stroma. Embedded within this chondromyxoid stroma there is an epithelial component which has ductular structures with bland small round nuclei. No evidence of significant nuclear pleomorphism is seen. No evidence of necrosis is present.

DIAGNOSIS:

Parapharyngeal mass: Features in keeping with a pleomorphic adenoma. No overt malignant features are seen.

Case Discussion

Key learning points: 

1. The enlargement of the stylomandibular interval is characteristic of a lesion within the deep lobe of the parotid.

2. Osseous remodelling suggests that the lesion has been present for a long time, implying benignity. 

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Case Information

rID: 28385
Case created: 24th Mar 2014
Last edited: 6th Feb 2017
System: Head & Neck
Inclusion in quiz mode: Included

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