Chronic sclerosing sialadenitis (Küttner tumor) is a chronic inflammatory disease of the submandibular gland that mimics malignancy by forming a hard, painless mass. It is now considered the prototype of IgG4-related disease — the majority of patients (60-80%) have elevated serum IgG4 levels and histology shows dense IgG4-positive plasma cell infiltration, storiform fibrosis, and obliterative phlebitis. It most commonly presents unilaterally or bilaterally in the submandibular gland. It is more common in males (M:F = 2:1). Mean age at diagnosis is 50-60. Histologically, four stages are defined: I (focal chronic sialadenitis), II (diffuse infiltration), III (progressive fibrosis), IV (advanced fibrosis and acinar atrophy). Sialolithiasis may accompany. IgG4-related disease may be multisystemic: lacrimal gland, pancreas, retroperitoneum, biliary tract, and aortic involvement may also be seen.
Age Range
40-70
Peak Age
55
Gender
Male predominant
Prevalence
Uncommon
The imaging findings of Küttner tumor are based on progressive fibrosis and cellular infiltration. IgG4-positive plasma cells and T lymphocytes infiltrate the gland parenchyma; storiform (whorled) fibrosis replaces the normal acinar structure. This dense fibrosis causes T2 hypointensity on MRI — the low water content and short T2 relaxation time of collagen fibers produce low signal. In advanced stages, acinar atrophy and duct proliferation increase the dominance of the fibrotic matrix. Obliterative phlebitis causes luminal narrowing and wall fibrosis in vascular structures — affecting the enhancement pattern. When sialolithiasis accompanies, additional obstructive changes (ductal dilation) are seen. Gland enlargement is uniform and firm, palpated as an encapsulated hard mass — this feature mimics malignancy and histological diagnosis through FNAB/biopsy is mandatory.
The most distinguishing MRI finding of Küttner tumor is T2 diffuse hypointensity — storiform fibrosis replaces normal gland parenchyma and the short T2 relaxation of collagen fibers produces low signal. This finding is critical for distinguishing from malignant tumors and acute inflammation.
On T2-weighted sequences, Küttner tumor shows diffuse hypointensity — this finding reflects dense storiform fibrosis and is the most distinguishing MRI finding. While normal submandibular gland shows intermediate-to-hyperintense T2 signal, in Küttner tumor the gland parenchyma shows T2 signal close to or lower than muscle. In advanced stages, T2 hypointensity becomes more pronounced as fibrosis increases. In early stages (stage I-II), focal T2 hyperintensity foci (inflammatory infiltration areas) may be seen. In bilateral involvement, symmetric T2 hypointensity is seen in both submandibular glands.
Report Sentence
The submandibular gland is diffusely enlarged showing homogeneous hypointense signal on T2-weighted sequences; this finding is consistent with dense fibrosis and chronic sclerosing sialadenitis (Küttner tumor) should be primarily considered.
On post-contrast T1 sequences, Küttner tumor shows homogeneous and prominent enhancement. The enhancement pattern is diffuse and uniform — different from the heterogeneous, necrotic enhancement of malignant tumors. Gland margins are smooth and well-defined. Delayed enhancement (slow washout) reflects the vascular characteristics of fibrotic tissue. On native T1 sequences, gland parenchyma appears isointense or mildly hypointense to muscle. Capsular enhancement may be observed.
Report Sentence
On post-contrast series, the submandibular gland demonstrates diffuse and homogeneous enhancement with smooth margins; this enhancement pattern supports a chronic inflammatory/fibrotic process rather than malignant tumor.
On B-mode ultrasonography, Küttner tumor appears as diffuse enlargement and heterogeneous echopattern in the submandibular gland. Gland parenchyma loses its normal homogeneous structure and assumes a heterogeneous hypoechoic appearance. In advanced stages, echogenicity may increase with fibrosis progression. If sialolithiasis accompanies, echogenic focus + posterior shadow is seen. Gland margins are generally smooth and well-defined. Vascularity on Doppler is variable — may be increased in acute inflammation, decreased in chronic fibrotic stage. US is the preferred modality for initial evaluation and FNAB guidance.
Report Sentence
The submandibular gland is diffusely enlarged with heterogeneous echopattern; smooth margins and clinical context (hard, painless mass) are consistent with chronic sclerosing sialadenitis.
On contrast-enhanced CT, Küttner tumor appears as diffuse enlargement and homogeneous enhancement of the submandibular gland. Gland margins are smooth and well-defined. On non-contrast CT, gland parenchyma may be isodense or mildly hyperdense relative to muscle — fibrosis increases density. If sialolithiasis accompanies, hyperdense calculus is seen. Surrounding fat planes are preserved — less invasive appearance than malignancy. In bilateral involvement, symmetric enlargement and enhancement are seen in both submandibular glands. CT is superior to MRI for evaluating accompanying sialolithiasis and bone involvement.
Report Sentence
On CT, the submandibular gland is diffusely enlarged with homogeneous enhancement; smooth margins and homogeneous structure favor a chronic inflammatory/fibrotic process over malignancy.
On DWI, Küttner tumor shows intermediate ADC values (typically 1.0-1.5 × 10⁻³ mm²/s). These ADC values are generally higher than malignant tumors (<1.0) and lower than pleomorphic adenoma (>1.5). Water diffusion is partially restricted in the fibrotic matrix — the collagen network slows free diffusion but is not as severe as cellular restriction in malignant tumors. ADC values may vary according to disease stage — higher ADC in early inflammatory stage, lower ADC in advanced fibrotic stage.
Report Sentence
The submandibular gland lesion demonstrates intermediate ADC values (ADC: [value] × 10⁻³ mm²/s); these findings with ADC values higher than malignant tumor and lower than benign tumor support a chronic inflammatory/fibrotic process.
Criteria
Serum IgG4 >135 mg/dL, >10 IgG4+ plasma cells/HPF on histology, storiform fibrosis, obliterative phlebitis.
Distinct Features
Multisystemic involvement may be present (lacrimal, pancreas, retroperitoneum), dramatic response to steroid therapy, may be bilateral.
Criteria
Normal serum IgG4, low IgG4+ plasma cell ratio on histology, chronic sclerosing sialadenitis morphology.
Distinct Features
Localized disease, no multisystemic involvement, variable steroid response, sialolithiasis more frequently accompanies.
Criteria
Advanced fibrosis and complete acinar atrophy. No functional gland tissue.
Distinct Features
Very pronounced T2 hypointensity, gland may be reduced, decreased enhancement, hard fibrotic mass, submandibulectomy may be required.
Distinguishing Feature
Adenoid cystic carcinoma has irregular margins, shows perineural spread, T2 intermediate (not hypointense), low ADC (<1.0). Küttner has smooth margins, no perineural spread, T2 hypointense, intermediate ADC.
Distinguishing Feature
Lymphoma may show low T2 signal but very low ADC (<0.7), FDG avid, homogeneous solid mass. Küttner is T2 hypointense but intermediate ADC, FDG generally low uptake, diffuse enlargement.
Distinguishing Feature
IgG4-related sialadenitis shows bilateral parotid + submandibular + lacrimal gland involvement (Mikulicz), Küttner is usually limited to submandibular gland. However, Küttner itself may also be IgG4-related.
Urgency
routineManagement
medicalBiopsy
NeededFollow-up
İİAB veya kor biyopsi ile histolojik tanı zorunlu (malignite ekartasyonu). IgG4-ilişkili ise steroid tedavi (prednizolon 30-40 mg/gün, 4-6 hafta). Multisistemik IgG4 taraması. Steroid yanıtsızlığında veya malignite şüphesinde submandibülektomi.Küttner tumor is a benign condition mimicking malignancy and histological diagnosis is mandatory. When IgG4-related, steroid therapy can produce dramatic response — gland size decreases within weeks. Serum IgG4 level and IgG4/IgG ratio are helpful in diagnosis. Multisystemic IgG4-related disease should be screened: lacrimal gland, pancreas (autoimmune pancreatitis), retroperitoneum, biliary tract, aorta, thyroid. Submandibulectomy is performed in cases not responding to steroid therapy or when malignancy cannot be excluded. Long-term follow-up is required — recurrence is seen in 20-30% when steroids are discontinued.
Clinical correlation is required.