Salivary gland lymphoma is a primary lymphoid neoplasm of salivary glands and accounts for 2-5% of all salivary gland malignancies. It most commonly occurs in the parotid gland because the parotid is the only major salivary gland containing intraglandular lymph nodes. MALT (mucosa-associated lymphoid tissue) lymphoma is the most common histological type and the risk of development in the setting of Sjögren syndrome is significantly increased (40-44 fold risk increase). Non-Hodgkin lymphoma (NHL) constitutes the vast majority of primary salivary lymphoma; diffuse large B-cell lymphoma (DLBCL), follicular lymphoma, and mantle cell lymphoma are other types. Hodgkin lymphoma is very rare in the parotid gland. Clinically presents as a painless, firm, rapidly growing parotid mass. Bilateral involvement occurs in 10-20%. Peak incidence between 50-70 years, more common in females (Sjögren-related MALT). Cervical lymphadenopathy may accompany. FDG PET-CT is critical for staging and treatment response assessment.
Age Range
50-80
Peak Age
65
Gender
Male predominant
Prevalence
Rare
The imaging findings of salivary gland lymphomas result from dense and homogeneous cellular infiltration of lymphoid cells. Lymphoid cells are small, high nuclear/cytoplasmic ratio cells; this compact cell arrangement creates intracellular water restriction and causes very low ADC values — the most characteristic DWI finding of lymphoma. Dense cellularity produces low-to-intermediate T2 signal. MALT lymphoma develops from Sjögren syndrome's chronic lymphocytic sialadenitis — prolonged antigenic stimulation leads to lymphoid transformation. The homogeneous structure of lymphoma (without necrosis, cystic degeneration, calcification) is reflected on imaging as a homogeneous mass. FDG uptake is high because lymphoid cells show increased glycolysis — in aggressive types (DLBCL), SUVmax can be very high.
Lymphoma's most distinguishing imaging triad: very low ADC (<0.7), homogeneous T2 low-to-intermediate signal, and high FDG uptake. This combination provides clear differentiation from other salivary gland tumors.
On DWI, salivary gland lymphoma demonstrates very marked diffusion restriction and very low ADC values (typically <0.7 × 10⁻³ mm²/s, frequently in the 0.4-0.6 range). These ADC values are the lowest among salivary gland tumors and are the strongest diagnostic criterion for distinguishing lymphoma from other malignant and benign tumors. Homogeneous low ADC reflects the dense and uniform arrangement of lymphoid cells.
Report Sentence
The mass in the parotid gland demonstrates very marked diffusion restriction and very low ADC values (ADC: [value] × 10⁻³ mm²/s); these findings are consistent with lymphoma.
On T2-weighted sequences, lymphoma shows low-to-intermediate homogeneous signal. Dense cellularity shortens T2 relaxation. Different from the marked T2 hyperintensity of pleomorphic adenoma and the T2 low signal of Warthin tumor. Homogeneous structure (no necrosis, cystic degeneration) is an important feature of lymphoma.
Report Sentence
The mass in the parotid gland demonstrates low-to-intermediate homogeneous signal on T2-weighted sequences; this signal pattern suggests a densely cellular tumor, particularly lymphoma.
On FDG PET-CT, lymphoma shows high FDG uptake (SUVmax typically 5-20+). DLBCL shows the highest FDG uptake while MALT lymphoma may show lower uptake. PET-CT is the gold standard for staging, treatment response (Deauville criteria), and recurrence assessment. Cervical, axillary, and other nodal involvement are evaluated in a single scan.
Report Sentence
On FDG PET-CT, the mass in the parotid gland demonstrates high FDG uptake (SUVmax: [value]); consistent with lymphoma and whole-body staging and core biopsy are recommended.
On contrast-enhanced CT, lymphoma appears as a homogeneous, mildly enhancing solid mass. Necrosis and cystic degeneration are generally absent (more homogeneous than carcinomas). Cervical lymphadenopathy may accompany. Bilateral parotid involvement is seen in 10-20% of cases.
Report Sentence
A homogeneous, mildly enhancing solid mass is identified in the parotid gland; absence of necrosis and cystic degeneration suggests lymphoma.
On B-mode US, lymphoma appears as a very hypoechoic, homogeneous mass — a 'pseudocystic' appearance may occur due to low echogenicity. Posterior acoustic enhancement may be observed. US is useful for evaluating cervical lymph nodes.
Report Sentence
A very hypoechoic, homogeneous, pseudocystic-appearing solid mass is identified in the parotid gland; lymphoma is considered and core biopsy is recommended.
Criteria
Mucosa-associated lymphoid tissue origin. Most common type. Sjögren-related.
Distinct Features
Indolent course, Sjögren background, low-moderate FDG, may be bilateral, good chemo/RT response.
Criteria
Diffuse large B-cell lymphoma. Aggressive type.
Distinct Features
Rapid growth, very high FDG (SUVmax >10-15), very low ADC, R-CHOP chemotherapy.
Criteria
Salivary gland involvement of systemic lymphoma. Intraparotid lymph node metastasis.
Distinct Features
Widespread nodal involvement, splenic involvement, bone marrow involvement accompany.
Distinguishing Feature
Warthin is cystic-solid mixed, pertechnetate hot, bilateral parotid tail. Lymphoma is solid homogeneous, very low ADC, pertechnetate negative.
Distinguishing Feature
IgG4 is diffuse gland enlargement, salt and pepper US, intermediate ADC, low FDG, steroid response. Lymphoma is focal mass, very low ADC, high FDG, transient steroid response.
Distinguishing Feature
Mucoepidermoid carcinoma has cystic-solid spectrum, T1 hyperintense mucinous component, heterogeneous. Lymphoma is solid, homogeneous, no cystic component, very low ADC.
Urgency
urgentManagement
medicalBiopsy
NeededFollow-up
Kor biyopsi ile histolojik tanı ve immünfenotipleme zorunludur (İİAB yetersiz). PET-BT ile tam vücut evreleme. MALT: izlem veya RT. DLBCL: R-CHOP kemoterapi. Sjögren sendromu zemininde MALT lenfoma taraması.Salivary gland lymphoma is a malignant disease requiring histological diagnosis and staging. Core biopsy (not FNAB) should be performed for histological subtype and immunophenotyping — treatment plan depends on histology. MALT lymphoma has an indolent course and is treated with radiotherapy in localized stages; chemotherapy/immunotherapy is needed in advanced stages. DLBCL is aggressive and R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, prednisolone) chemotherapy is standard treatment. PET-CT is the gold standard for staging and treatment response assessment (Deauville criteria). In patients with Sjögren syndrome history, MALT lymphoma risk is 0.5-1% annually and regular follow-up is required.
Treatment for MALT lymphoma is chemo/radiotherapy. Biopsy is required for diagnosis. Regular follow-up recommended for Sjögren patients.