Perineural Spread and Labral Enhancement on MRI
Critical Clarification
There appears to be a fundamental disconnect in this question: "labrum" (a fibrocartilaginous structure found in joints like the shoulder or hip) and "perineural spread" (tumor extension along cranial or peripheral nerves) are anatomically and pathologically unrelated entities. If labral enhancement is truly the only finding, this would not be consistent with perineural spread of malignancy, as perineural spread manifests as nerve thickening, enhancement, or widening of neural foramina—not labral enhancement 1.
If the Question Refers to Perineural Spread in Head and Neck Region
Most Common Malignancies Associated with Perineural Spread
The cancers most commonly demonstrating perineural spread in the head and neck are, in order of frequency: squamous cell carcinoma (cutaneous and mucosal), adenoid cystic carcinoma, melanoma, lymphoma, basal cell carcinoma, and mucoepidermoid carcinoma 1.
Primary Malignancies by Frequency:
Squamous cell carcinoma (both cutaneous and mucosal origin) is the most common malignancy showing perineural spread in head and neck regions 1
Adenoid cystic carcinoma has the highest propensity for perineural invasion among salivary gland malignancies, with perineural spread being particularly common and often requiring postoperative radiotherapy due to inability to achieve complete radical resection 1, 2, 3
Melanoma is the third most common malignancy demonstrating perineural spread in head and neck regions 1
Lymphoma can demonstrate perineural spread patterns 1
Basal cell carcinoma shows perineural involvement, though perineural spread poses greatly increased risk of recurrence 1
Mucoepidermoid carcinoma is among the salivary gland malignancies that can demonstrate perineural spread 1
Nerves Most Commonly Affected
The trigeminal nerve (CN V) and facial nerve (CN VII) are the most commonly affected by perineural tumor spread, though any nerve in the vicinity of a malignancy may become involved 1, 2, 3.
Imaging Characteristics of True Perineural Spread
MRI is superior to CT for detecting perineural spread, with sensitivity of 100% and specificity of 85% for MRI versus 88% sensitivity and 89% specificity for CT in detecting perineural spread of adenoid cystic carcinoma to the skull base 5.
Radiologic Criteria for Perineural Spread:
- Nerve thickening (regardless of enhancement) 5
- Contrast enhancement of nerves (regardless of size) 5
- Widening of bony foramina or neural canals 5
- Abnormal signal intensity along nerve pathways 6
- Effacement of normal perineural fat planes 1
Clinical Significance
Perineural tumor spread on imaging is associated with worse prognosis and requires aggressive treatment planning, as it influences the extent of surgery and the dosage and fields of radiation therapy 1, 3.
- Perineural spread should be distinguished from perineural invasion, which is local invasion detected on histopathologic diagnosis at the primary tumor site 1
- Deep local recurrences and perineural tumor spread can be inaccessible to clinical assessment and may go overlooked, particularly in early stages 1
- If large nerve involvement is suspected, MRI should be considered to evaluate extent and rule out skull involvement 1
Recommendation for This Clinical Scenario
If labral enhancement is truly the only abnormal finding on MRI, this does not represent perineural spread of malignancy. Consider alternative diagnoses for isolated labral enhancement (such as labral tear, inflammatory arthropathy, or infection depending on the joint involved), and if there is clinical concern for perineural spread, obtain dedicated high-resolution MRI with pre- and post-contrast imaging focused on the cranial nerves and skull base using thin-cut sequences 1.