From the Guidelines
Salivary gland neoplasms are typically evaluated using imaging modalities such as MRI, CT, or ultrasound, which help identify the location, size, and extent of the tumor, as well as potential lymph node involvement or perineural spread, as recommended by the American Society of Clinical Oncology 1, 2. The most recent and highest quality study, published in 2023, suggests that MRI is the modality of choice for initial staging of major salivary gland cancer due to its superior soft tissue contrast resolution, which allows for better delineation of the soft tissue extent of the tumor and detection of perineural spread 3. Some key features of salivary gland neoplasms that can be identified through imaging include:
- Location: major or minor salivary gland
- Size: can range from small to large
- Extent: can be localized or invasive, with potential perineural spread or lymph node involvement
- Characteristics: can be benign or malignant, with varying degrees of aggressiveness The use of advanced MRI techniques, such as diffusion-weighted imaging and perfusion imaging, may improve the ability to distinguish between benign and malignant tumors, although these tools are not consistently used in routine clinical practice 3. In terms of pathological images, salivary gland neoplasms can exhibit a range of histological patterns, including pleomorphic adenoma, Warthin's tumor, mucoepidermoid carcinoma, adenoid cystic carcinoma, and acinic cell carcinoma, which can be diagnosed using a combination of imaging, fine-needle aspiration, and immunohistochemistry 3.
From the Research
Pathological Images of Salivary Gland Neoplasms
The pathological images of salivary gland neoplasms can be evaluated using various imaging modalities, including:
- Ultrasound: ideal for initial assessment of lesions in the superficial parotid and submandibular gland, providing excellent resolution and tissue characterization without radiation hazard 4
- MRI: best imaging modality to evaluate salivary gland tumors, especially for lesions in the deep lobe of parotid gland, minor salivary glands, and sublingual gland, and to assess facial nerve involvement or skull base involvement 4, 5, 6
- CT: complementary to MRI, offering useful information on tumor extent and local invasion 4, 7
- Fine needle aspiration biopsy (FNAB): provides a safe means to obtain cytological confirmation, with a high positive predictive value (PPV) for pleomorphic adenoma 8
- MR spectroscopy: may differentiate malignant and benign salivary gland tumors, but its role in clinical practice is not well established 4
- Diffusion-weighted imaging and PET-CT: help with characterization of salivary gland tumors, although biopsy or excision is often needed for definitive tissue diagnosis 7, 6
Characteristics of Salivary Gland Neoplasms on Imaging
The characteristics of salivary gland neoplasms on imaging include:
- Homogenous T2 hyperintensity, well-circumscribed borders, and solid contrast enhancement on MRI, suggestive of pleomorphic adenoma 8
- Fibrillary stroma, mesenchymal elements, plasmacytoid myoepithelial cells, epithelial cells forming ducts or tubules, and the absence of nuclear atypia on FNAB, suggestive of pleomorphic adenoma 8
- Nodal involvement and systemic involvement can be assessed using imaging modalities such as ultrasound, CT, and MRI 4, 7, 5