Salivary Gland Lesions
- The big three salivary glands are the parotid, submandibular, and sublingual — and "where" the lesion lives is half the diagnosis.
- The single most useful split is diffuse gland disease (think inflammation, infection, autoimmune) versus a focal mass (think tumor or cyst).
- For a focal parotid mass, the most common culprit is a benign pleomorphic adenoma; Warthin tumor loves the parotid tail and loves smokers.
- A rough rule of thumb: the smaller the gland, the higher the chance a tumor in it is malignant.
- Ultrasound is the friendly first look; MRI is the workhorse for mapping a mass and watching the facial nerve.
Your spit is made by glands, and like any small factory, those glands can clog, swell, get infected, or grow a lump. The salivary glands are just that — squishy little saliva factories tucked around your jaw — and radiology's job is to figure out which kind of trouble they're in. The good news: a handful of questions get you most of the way there.
Meet the glands
There are three pairs of major salivary glands, and they sit in predictable neck real estate you can practically point to.
- Parotid — the big one, draped over the back of the jaw in front of the ear. It is the only gland with the facial nerve running straight through it, which is why every parotid report obsesses over whether a mass is on the superficial or deep side of that nerve.
- Submandibular — under and behind the jaw, the gland most likely to grow a stone.
- Sublingual — the small one in the floor of the mouth.
Here is a genuinely useful pattern: tumors in big glands tend to be benign, and tumors in small glands tend to be more often malignant. The parotid is the friendliest, the sublingual the most suspicious. Don't quote it as a percentage on rounds, but it's a reliable instinct.
The first fork in the road: diffuse vs. focal
Before naming anything, I ask one question — is the whole gland unhappy, or is there a discrete lump? It splits the entire topic in two.
| Pattern | What it looks like | Usual suspects |
|---|---|---|
| Diffuse | The gland is swollen, inflamed, or studded throughout | Infection, ductal obstruction, autoimmune (e.g., Sjögren), sialadenitis |
| Focal | One rounded mass against otherwise normal gland | Benign tumor, malignant tumor, cyst |
A salivary "stone" — a sialolith — is the classic plumbing problem. Saliva backs up behind it like a kinked garden hose, the gland swells (especially at mealtimes when it's asked to produce), and it hurts. CT is excellent here because most of these stones are calcified and light up bright white.
When it's a mass: the parotid line-up
Most salivary masses live in the parotid, and most of those are benign. Two names do the heavy lifting.
Pleomorphic adenoma is the most common salivary tumor overall — a well-defined, slow-growing benign lump. On MRI it tends to be strikingly bright on T2-weighted images, like a little water balloon. It's benign, but it has a long-term habit of recurring if incompletely removed, so it gets respect.
Warthin tumor is the runner-up, and it has personality: it strongly favors the parotid tail, has a real association with smoking, and is the one classically allowed to show up on both sides.
Benign on imaging is never a free pass. Features that should raise your eyebrows toward malignancy include ill-defined or infiltrative margins, invasion into surrounding fat or muscle, and suspicious-looking neck lymph nodes. And a patient with facial nerve weakness plus a parotid mass is a red flag until proven otherwise — nerves don't stop working for polite tumors.
How we actually image them
Each modality earns its keep for a different job, so the trick is matching the tool to the question.
| Modality | Best for |
|---|---|
| Ultrasound | First-line look at a superficial mass; cheap, fast, and great for guiding a biopsy. Add Doppler to check the blood flow. |
| CT | Finding stones and assessing acute infection or abscess. |
| MRI | The deep dive — mapping a mass, judging margins, and tracing the facial nerve path. |
The honest limit of ultrasound is depth: the deep part of the parotid hides behind the jawbone, and sound waves can't see through bone. That's exactly where MRI takes over, because it doesn't care about bone shadows and shows soft tissue beautifully.
The one differential worth memorizing
When the report says "diffuse, bilateral parotid disease," your brain should jump to a short list: autoimmune (classically Sjögren syndrome, often with multiple tiny cysts), infection, and — in the right patient — HIV-related lymphoepithelial cysts. Bilateral and diffuse points away from a single tumor and toward a systemic process.
Answer two questions in order — diffuse or focal? then which gland? — and you've already narrowed a scary-sounding salivary case down to a short, sensible list. Everything else is detail.