DEAR MAYO CLINIC: My 8-year-old daughter has had intermittent pain underneath her tongue for nearly two years. Her doctor suspects salivary gland stones but cannot see them and tells me they are not common in children. What are salivary gland stones and how are they treated?

ANSWER: Particularly if your daughter's pain occurs when she's eating, she might have one or more salivary gland stones. Your doctor is right. They are unusual—but not unheard of—in children.

Salivary gland stones form in the ducts of the salivary glands in and around the mouth and throat, including near the upper teeth, under the tongue and across the floor of the mouth.

Salivary glands produce saliva. Stones can partially or completely block the salivary ducts, the pathways for saliva to travel from these glands into the mouth. The stones can be as large as a pea, but much smaller stones can cause problems, depending on where they are lodged. The pain most often occurs with eating, when the salivary glands have kicked into gear to moisten food. Blocked salivary ducts also can cause infection—another source of pain.

Researchers aren't sure exactly what causes salivary gland stones or what might put an individual at increased risk. Their formation is similar to the process that causes kidney stones. Salivary gland stones are made up largely of calcium, which usually—but not always—makes them visible on imaging studies.

To confirm your daughter's diagnosis, I'd recommend a consultation with an ear, nose and throat specialist. Diagnostic tests would likely include an ultrasound or CT scan. Sometimes, but not always, a doctor can see or feel stones during an exam. Other times, the physician must rely on symptoms alone to make the diagnosis.

If salivary duct stones are confirmed, treatment options include:

Increasing saliva production: Drinking more water and other steps to increase saliva production may help minimize symptoms. Sucking on lemon drops or chewing sugarless gum can help increase saliva production and possibly wash out the stone.

Medication: If an infection is present, an antibiotic will reduce pain and swelling.

Stone removal: During a sialoscopy procedure, a doctor uses a specialized scope to look into the salivary duct. In some cases, tools can be used to grab and remove the stone, or crush it and flush out the pieces. In children, this minimally invasive procedure requires general anesthesia, but is typically done on an outpatient basis. If the stone can't be retrieved or crushed via the scope, it can be removed through other surgical procedures.

It is important that you work with a doctor to confirm the diagnosis and develop a treatment plan. A salivary gland stone that doesn't become dislodged will continue to cause pain and swelling when eating.

Other conditions also can cause mouth pain and swelling. A ranula, which is a cyst on the floor of the mouth, can interfere with the salivary glands. Also, dental or other neck infections or, rarely, a tumor can cause these symptoms. Pain from these conditions wouldn't necessarily be linked with eating, and different courses of treatment would be needed.—Laura Orvidas, M.D., Ear, Nose and Throat, Mayo Clinic, Rochester, Minn.

(Medical Edge from Mayo Clinic is an educational resource and doesn't replace regular medical care. To submit a question, write to: medicaledge@mayo.edu, or Medical Edge from Mayo Clinic, c/o TMS, 2225 Kenmore Ave., Suite 114, Buffalo, N.Y., 14207. For health information, visit www.mayoclinic.com.)