martedì 30 settembre 2008

Sialadenitis with sialolithiasis


Uptake image series: Normal thyroid uptake. Symmetric radiotracer visualized in the sublingual glands. Expected radiopharmaceutical by the bilateral parotid glands and right submandibular gland. Increased uptake in the left submandibular gland. Increased radiopharmaceutical visualized in the oral cavity.
L lat washout and R lat washout image: Unchanged symmetric activity in the thyroid gland. Expected washout and decreased radiopharmaceutical in the parotid glands and right submandibular gland. Decreased washout in the left submandibular gland.
15 min post lemon image: Decreased washout of the radiopharmaceutical in the left submandibular gland with normal washout in the remaining salivary glands.

Differential diagnosis:
- Sialadenitis
- Warthin's tumor
- Oncocytoma
- Oxyphilic adenomas

Diagnosis: Sialadenitis with sialolithiasis

Follow-up: Patient subsequently had her left submandibular gland surgically removed. In the operating room they found a calcified stone in the parenchyma of the gland.

Key Points

Nuclear sialography is used to assess the function of the salivary glands. CT and US are used for structural information. CT and US can be used to differentiate masses from inflammation and benign from malignant. US-guided fine needle biopsy has a high degree of accuracy.
The salivary glands consist of three paired exocrine glands. The parotid glands empty into the oral cavity through Stenson's duct. The submandibular glands empty through Wharton's ducts. The sublingual glands are the third type and connect to the oral cavity through multiple small ducts.
Rinsing the mouth with water before Tc99m-pertechnetate increases retention in the salivary gland and delays its secretion into the oral cavity. Patient is placed in the seated position with the head tilted back to prevent superimposition of the thyroid gland. A dynamic blood flow study should be performed, followed by sequential 1 minute images for 60 minutes. This should demonstrate simultaneous, symmetric uptake of the three paired exocrine glands.
The salivary gland is then subjected to gustatory stimulation with a lemon or with a 1:1 lemon juice to water mix (rinse for 5 seconds and spit). Normally see rapid symmetrical and complete resolution of radiopharmaceutical from the salivary glands. It is useful to obtain lateral views of the head and neck to confirm radiotracer in the saliva of the oral cavity after gustatory stimulation.
Warthin's tumor (papillary cystadenoma) appears as a focal region of increased uptake. Oncocytomas and oxyphilic adenomas are other tumors which may have increased radiopharmaceutical uptake. Increased uptake could also be seen with acute inflammation.
Metastatic lesions appear as focal regions of decreased uptake. Also seen with cysts, enlarged lymph nodes, and chronic inflammatory disease. Could also result from congenital aplasia, obstructive sialolithiasis, trauma, or radiotherapy.
Mixed benign tumors are the most common type of tumor of the salivary glands and may present as focal areas of increased or decreased signal.
With Sjögren's syndrome, there may be asymmetric arrival or delayed accumulation of radiotracer. There may be absent or decreased response to gustatory stimulation, especially the submandibular glands. The presence of high Ga-67 concentration in the lacrimal and salivary glands in pathognomonic for Sjögren's syndrome. A poor response to gustatory stimulation can also be seen with systemic connective tissue disease and viral parotitis or mumps, or following radiotherapy. Failure to excrete radiotracer is seen in stenosis or blockage of the salivary duct.

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