Adrenal lymphoma is a lymphoproliferative neoplasm involving the adrenal glands. Primary adrenal lymphoma is exceedingly rare, accounting for less than 1% of all adrenal malignancies; secondary involvement (adrenal spread of systemic lymphoma) is far more common, observed in up to 25% of patients with disseminated non-Hodgkin lymphoma. Histologically, diffuse large B-cell lymphoma (DLBCL) is the most common subtype. Bilateral involvement is characteristic, seen in 60-80% of primary adrenal lymphoma cases, and this feature serves as an important distinguishing clue from adrenal metastasis. It typically occurs between ages 60-70 with slight male predominance. Some patients may present with adrenal insufficiency (Addisonian crisis). On imaging, it appears as large, homogeneous or mildly heterogeneous, hypovascular masses; differentiation from metastasis and adrenocortical carcinoma is required.
Age Range
50-85
Peak Age
70
Gender
Male predominant
Prevalence
Rare
Adrenal lymphoma is characterized by abnormal proliferation of lymphoid cells within the adrenal gland. In the primary form, neoplastic transformation originates from small lymphoid cell populations within the adrenal gland or from lymphatic tissue surrounding the adrenal. In the secondary form, systemic lymphoma spreads to the adrenal glands via the hematogenous route; the rich vascular architecture of the adrenal glands is thought to predispose to this spread. Pathologically, lymphoma cells diffusely infiltrate the adrenal cortex and medulla, replacing normal adrenal tissue — this can cause adrenal insufficiency in bilateral and massive involvement. On imaging, because lymphoma cells form a dense cellular population, marked diffusion restriction is seen on DWI (high cellularity = restricted movement of water molecules). The hypovascular characteristic on CT reflects the non-neovascular nature of the tumor — lymphoma cells do not generate intense angiogenesis, hence enhancement is mild or homogeneous. On MRI, T2 signal intensity is inversely proportional to cellularity; highly cellular lymphomas appear intermediate or mildly hyperintense on T2, while necrotic areas show marked hyperintensity.
Bilateral, large, homogeneous adrenal masses showing marked diffusion restriction (low ADC) on DWI is the most characteristic imaging combination for adrenal lymphoma. This triad (bilateral + large + diffusion restriction) is the signature finding of adrenal lymphoma and the strongest imaging criterion for differentiation from metastasis or carcinoma.
On non-contrast CT, bilateral, large (typically >4 cm), homogeneous, soft tissue density adrenal masses are observed. Pre-contrast density is usually between 30-45 HU, significantly higher than the <10 HU values typical for lipid-rich adenoma. The masses may preserve adrenal gland contour or show extra-adrenal extension. Necrosis and hemorrhage can be seen in large masses but are rare in small-to-medium lesions, with homogeneous appearance being characteristic.
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Large homogeneous soft tissue density masses (approximately ... HU) are observed in both adrenal glands; the bilateral involvement pattern should primarily suggest adrenal lymphoma.
On contrast-enhanced CT in the portal venous phase, adrenal masses show mild and homogeneous enhancement. The degree of enhancement is typically 10-30 HU increase, significantly less than hypervascular tumors (pheochromocytoma, adrenocortical carcinoma). Central necrosis areas may appear as non-enhancing hypodensity in large masses. Pressure effect or invasion of adjacent structures (kidney, diaphragm, great vessels) should be evaluated.
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The adrenal masses demonstrate mild and homogeneous enhancement in the portal venous phase, and this hypovascular pattern is consistent with lymphoma.
On DWI (b=800-1000 s/mm²) sequences, adrenal masses show markedly high signal and on ADC maps demonstrate markedly low signal (ADC value typically <1.0 × 10⁻³ mm²/s). This finding reflects the high cellularity of lymphoma and is one of the strongest MRI criteria for diagnosis. Diffusion restriction can also be seen in metastases, but the degree in lymphoma is generally more pronounced. ADC values can also be used for monitoring treatment response — an increase in ADC values is expected after successful treatment.
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Marked diffusion restriction on DWI and low signal on ADC maps (ADC: ... × 10⁻³ mm²/s) are observed in the adrenal masses; this finding is consistent with lymphoma, a highly cellular pathology.
On T2-weighted imaging, adrenal lymphoma masses typically show intermediate to mildly hyperintense signal. Marked T2 hyperintensity is not expected due to dense cellularity — this feature can help differentiate from metastasis and adrenal carcinoma, which are usually more hyperintense on T2. Homogeneous signal is typical especially in small-to-medium sized lesions. Central necrosis areas in large masses may appear markedly hyperintense on T2. No signal drop is seen on chemical shift sequences because lymphoma does not contain intracellular lipid — this finding provides clear differentiation from adenoma.
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Intermediate signal intensity on T2-weighted imaging is observed in the adrenal masses, consistent with a densely cellular lesion; absence of signal drop on chemical shift sequences excludes the possibility of adenoma.
On chemical shift imaging (in-phase and opposed-phase), no signal drop is observed in adrenal lymphoma. Signal intensity does not differ between in-phase and opposed-phase images. This finding carries critical differential diagnostic value: while lipid-rich adenomas show marked signal drop on opposed-phase, this finding is absent in lymphoma. It can also occur with lipid-poor adenoma; however, lipid-poor adenoma is typically small (<4 cm) and unilateral, while lymphoma is large and often bilateral with additional marked diffusion restriction on DWI.
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No signal drop is observed on opposed-phase chemical shift sequences, excluding intracellular lipid content; this finding eliminates the possibility of adenoma and should be evaluated towards lymphoma, metastasis, or carcinoma.
On FDG PET-CT, adrenal lymphoma masses show intense FDG uptake. SUVmax values are typically >10, reflecting high metabolic activity. In bilateral involvement, symmetric intense uptake may be seen in both adrenal glands. FDG-PET plays a critical role in diagnosis, staging, and treatment response assessment of adrenal lymphoma. Complete metabolic response after treatment (Deauville score 1-3) is a favorable prognostic indicator, while persistent FDG uptake suggests refractory disease.
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Intense FDG uptake (SUVmax: ...) is observed in both adrenal glands on FDG PET-CT; this metabolic activity pattern is highly consistent with lymphoma.
On gallium-67 scintigraphy, adrenal lymphoma masses show intense Ga-67 uptake. Gallium-67 is taken up by lymphoma cells via the transferrin receptor and is sensitive for detecting actively proliferating lymphoid tissue. Although largely replaced by FDG PET-CT today, it may still be used in centers where PET-CT is unavailable. Bilateral symmetric intense uptake is quite characteristic for adrenal lymphoma.
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Intense uptake is observed in the adrenal glands on gallium-67 scintigraphy, consistent with a lymphoproliferative pathology.
Criteria
At diagnosis, disease is confined solely to the adrenal glands with no extra-adrenal involvement. Very rare, constituting less than 1% of all extranodal lymphomas. Diagnosis requires: (1) unilateral or bilateral adrenal mass, (2) histological lymphoma confirmation, (3) no evidence of lymphoma elsewhere. Most are DLBCL subtype.
Distinct Features
Bilateral involvement seen in 60-80%, an important distinguishing feature from metastasis. Presentation with adrenal insufficiency seen in up to 60%. Prognosis is worse than secondary form (5-year survival 20-30%).
Criteria
Spread of systemic lymphoma to the adrenal glands. Adrenal involvement can be seen in up to 25% of disseminated non-Hodgkin lymphoma patients. Usually occurs in advanced stage (Ann Arbor stage IV) disease. May be seen together with other extranodal involvement sites (spleen, liver, bone marrow).
Distinct Features
More common than primary form. Bilateral involvement may occur but unilateral is also frequent. Usually there is known lymphoma history at diagnosis. Extra-adrenal involvement sites are detected on PET-CT. Prognosis may be better than primary form as chemotherapy response is generally better.
Criteria
Constitutes 70-80% of adrenal lymphoma cases. Histologically characterized by diffuse proliferation of large B-cells. Shows CD20+, CD79a+, BCL-6+/- expression on immunohistochemistry. Has aggressive course with rapid growth potential.
Distinct Features
On imaging, usually appears as large, rapidly growing, mildly heterogeneous masses. Shows intense uptake on FDG-PET (SUVmax >10). Marked diffusion restriction on DWI is typical. Response rate to R-CHOP chemotherapy is approximately 60-70%.
Distinguishing Feature
Adrenal metastasis usually has known primary malignancy history; generally more hyperintense on T2 and shows less pronounced diffusion restriction on DWI. Bilateral involvement can also be seen in metastasis but usually with asymmetric size; more symmetric bilateral masses are typical in lymphoma. Necrosis and heterogeneous enhancement are more common in metastasis.
Distinguishing Feature
Adrenocortical carcinoma is usually unilateral, very large (>6 cm), markedly heterogeneous mass; necrosis, hemorrhage, and calcification are common. Enhancement is heterogeneous and contains hypervascular components. Lymphoma is more homogeneous and calcification is rare. ACC is often hormonally active (Cushing, virilization); lymphoma is hormonally inactive.
Distinguishing Feature
Pheochromocytoma is markedly hyperintense on T2 ('light bulb sign'), appearing very bright; lymphoma shows intermediate signal on T2. Pheochromocytoma is hypervascular with intense arterial phase enhancement; lymphoma is hypovascular. Pheochromocytoma secretes catecholamines (hypertension, tachycardia, sweating triad); lymphoma is hormonally inactive. Pheochromocytoma shows uptake on MIBG scintigraphy, lymphoma does not.
Distinguishing Feature
Adrenal hemorrhage is hyperdense on CT in acute phase, hyperintense on T1 on MRI; signal pattern changes over time (hemorrhage stages). Does not show enhancement. Lymphoma shows enhancement and has diffusion restriction on DWI. Hemorrhage is usually associated with anticoagulant use, trauma, or stress; decreases in size over time. Lymphoma increases in size.
Urgency
urgentManagement
medicalBiopsy
NeededFollow-up
specialist-referralAdrenal lymphoma diagnosis requires histological confirmation — percutaneous core biopsy or surgical biopsy. Pheochromocytoma must be excluded before biopsy (catecholamine measurement). Hematology/oncology consultation is mandatory after diagnosis. Standard treatment for DLBCL is R-CHOP (rituximab + cyclophosphamide + doxorubicin + vincristine + prednisone) for 6-8 cycles. Endocrinology evaluation and glucocorticoid replacement may be needed for adrenal insufficiency in bilateral massive involvement. Treatment response is evaluated with PET-CT (Lugano classification, Deauville score). After complete metabolic response, CT/PET-CT follow-up at 3-6 month intervals for 2 years is recommended.
Primary adrenal lymphoma is rare but should be considered when bilateral adrenal enlargement is present. Biopsy is essential for diagnosis. Chemotherapy is the primary treatment. Adrenal insufficiency may be present.