Sialolithiasis (salivary gland stone) is the formation of calculi composed of calcium phosphate and calcium carbonate crystals in salivary ducts or gland parenchyma. It most commonly occurs in the submandibular gland (80-90%); this is due to the long and tortuous course of Wharton's duct, mucinous and alkaline secretion, and drainage against gravity. It occurs in the parotid gland in 5-10% and sublingual gland in 1-2%. It is twice as common in males. Peak incidence is between 30-60 years. Stones can be located at any level of the duct — 80% are intraductal and 20% are in the gland parenchyma. Clinically, meal-related pain and swelling (obstructive symptoms) are typical. Recurrent obstruction is the most common cause of acute and chronic sialadenitis. Submandibular stones are 80-90% calcified while parotid stones are 40-60% calcified and may be radiolucent.
Age Range
30-60
Peak Age
45
Gender
Male predominant
Prevalence
Common
The imaging findings of sialolithiasis are based on the mineral composition of the stone and its obstructive effects. Stones consist of calcium phosphate (hydroxyapatite) and calcium carbonate crystals; the high atomic numbers of these minerals increase X-ray attenuation, creating hyperdensity on CT and posterior acoustic shadow on US. Ductal obstruction by the stone causes upstream ductal dilation, gland edema, and secretory stasis — these changes are seen as dilated duct and enlarged gland on US. Chronic obstruction develops fibrosis, atrophy, and chronic inflammation in the gland — reflected as T2 signal changes in gland parenchyma on MRI. When acute obstructive sialadenitis is complicated by superinfection, periglandular fat infiltration and abscess formation create additional imaging findings. The mucinous, alkaline, calcium-rich secretion of the submandibular gland and the anatomical disadvantages of Wharton's duct (long, tortuous, drainage against gravity) explain why stone formation is much more common in this gland.
The pathognomonic US finding of sialolithiasis is an echogenic focus with posterior acoustic shadow within the duct and ductal dilation proximally. This triple combination (echogenic focus + shadow + dilation) confirms the diagnosis and additional imaging is generally unnecessary.
B-mode ultrasonography is the primary diagnostic modality for sialolithiasis. The stone appears as a highly echogenic (bright) focus within the duct or gland parenchyma with a prominent posterior acoustic shadow (clean shadow) behind it. The shadow manifests as signal loss in tissues behind the stone. Stone size generally ranges from 2-30 mm; small stones (<2-3 mm) may be difficult to demonstrate on US. Ductal dilation (>3 mm from normal) and gland enlargement proximal to the stone support obstruction. In acute obstruction, gland parenchyma appears diffusely hypoechoic (edema). In chronic cases, gland parenchyma may be heterogeneous and reduced (atrophy and fibrosis). US sensitivity is 90%+ for submandibular stones while 50-70% for parotid stones (due to the deep course of the parotid duct and mandibular shadow).
Report Sentence
A highly echogenic focus with posterior acoustic shadow is identified within the duct/parenchyma of the submandibular gland, with ductal dilation proximally; findings are consistent with sialolithiasis and obstructive sialopathy.
Non-contrast CT is the most reliable diagnostic modality for sialolithiasis and can demonstrate stones undetectable on US. Stones appear as high-density (100-1000+ HU) hyperdense structures. While 80-90% of submandibular stones are calcified, 40-60% of parotid stones are calcified with the remaining stones being poorly calcified or radiolucent. CT is also the most accurate modality for determining the exact location (intraductal vs intraglandular), size, and number of stones. Ductal dilation, gland enlargement, and periglandular inflammation related to obstruction can be evaluated on contrast-enhanced CT. Multiple stones are seen in 20-30%. Stone shape is generally oval or round; irregular stones may consist of multiple small fragments.
Report Sentence
On non-contrast CT, a [size] mm hyperdense calculus is identified within the duct/parenchyma of the submandibular gland; ductal dilation is present proximally, consistent with obstructive sialolithiasis.
On T2-weighted MRI, salivary gland stones appear as signal void (hypointense); the mineral structure of the stone either lacks protons or has very short T2. Dilated duct filled with T2 hyperintense fluid is seen around and proximal to the stone — this finding demonstrates obstruction. MR sialography (heavily T2-weighted sequence) excellently demonstrates duct anatomy and obstruction level. In the gland parenchyma, diffuse T2 hyperintensity (edema) is seen in acute inflammation, T2 hypointensity (fibrosis) in chronic cases. MRI's advantage is absence of radiation and superior soft tissue contrast; disadvantage is inability to demonstrate small stones and calcification degree as well as CT.
Report Sentence
A structure creating signal void within the submandibular gland duct is identified on T2-weighted sequences, with T2 hyperintense dilated duct proximally; findings are consistent with sialolithiasis and obstructive sialopathy.
On contrast-enhanced CT, gland enlargement and diffuse enhancement related to obstructive sialadenitis are observed. Gland parenchyma shows homogeneous or heterogeneous enhancement. Periglandular fat infiltration demonstrates spread of inflammation to surrounding tissues. Abscess formation appears as a hypodense collection with peripheral rim enhancement. Ductal dilation is seen as a linear hypodense structure on contrast series. In chronic cases, the gland may be reduced and enhancement may be decreased (atrophy and fibrosis). Contrast-enhanced CT is useful for evaluating complications (abscess, cellulitis) and the stone's relationship to surrounding structures.
Report Sentence
On post-contrast series, the submandibular gland is diffusely enlarged with increased enhancement; periglandular fat infiltration is present, consistent with obstructive sialadenitis.
MR sialography (3D-CISS, FIESTA, or heavily T2-weighted sequences) is a non-invasive method that has replaced invasive conventional sialography. Fluid within salivary ducts is used as natural contrast — ducts filled with T2 hyperintense fluid appear bright, while stones appear as signal voids (filling defects). The level of obstruction, degree of ductal dilation, and condition of gland parenchyma can be assessed. Holding lemon juice in the mouth (sialagogue stimulation) can improve imaging quality by increasing ductal filling. MR sialography is valuable in differentiating tumor from stone, preoperative mapping of duct anatomy, and detection of multiple stones.
Report Sentence
On MR sialography, a signal void creating a filling defect within the salivary duct is identified, with prominent ductal dilation proximally; consistent with sialolithiasis.
Criteria
Stone localized within the duct (80%). Wharton's duct or Stensen's duct.
Distinct Features
Ductal dilation prominent, easy detection with US and CT, removable by sialendoscopy (<5mm), surgical exploration of floor of mouth.
Criteria
Stone localized within gland parenchyma (20%). Generally larger.
Distinct Features
Ductal dilation may be absent, gland enlargement, accompanied by chronic sialadenitis findings, submandibulectomy may be needed.
Criteria
Two or more stones. In 20-30% of patients.
Distinct Features
Obstruction at different levels, higher complication risk, mandatory counting of all stones with CT, multiple removal by sialendoscopy or surgery.
Distinguishing Feature
Acute sialadenitis can develop without stone (bacterial/viral); no echogenic focus and posterior shadow on US. In stone-related sialadenitis, the obstructive stone is demonstrated.
Distinguishing Feature
Küttner tumor presents with diffuse gland enlargement, stone may accompany but primary pathology is IgG4-related inflammation and fibrosis. Diffuse T2 hypointensity (fibrosis) is prominent on MRI.
Distinguishing Feature
Ranula is a cystic lesion from sublingual gland localized in the floor of mouth; no stone, no echogenic focus and posterior shadow, anechoic cystic structure.
Urgency
routineManagement
interventionalBiopsy
Not NeededFollow-up
Tedavi taş boyutu, lokasyonu ve semptom şiddetine göre belirlenir. Küçük taşlar (<5 mm) sialendoskopi ile çıkarılabilir. Büyük intraductal taşlar ağız tabanı eksplorasyonu ile, intraglandüler taşlar submandibülektomi ile tedavi edilir. Litotripsi seçilmiş olgularda uygulanabilir. Komplikasyon geliştiğinde (apse) acil drenaj gerekir.Minimally invasive approaches are preferred in the treatment of sialolithiasis. Sialendoscopy has become the primary treatment method in recent years — endoscopic lithotripsy and removal are performed for small and medium-sized stones (60-90% success). For large or impacted stones, a combined approach (sialendoscopy-assisted surgery) is preferred. Gland excision (submandibulectomy or parotidectomy) may be required in cases with recurrent obstruction and chronic sialadenitis. Extracorporeal shock wave lithotripsy (ESWL) is used at some centers for stone fragmentation. Antibiotics, hydration, and sialagogue stimulation are used in acute obstructive sialadenitis treatment. Surgical drainage is mandatory when abscess develops.
Small stones can be removed by sialendoscopy. Large stones may require surgery. Risk of recurrent infection.