Yes, systemic lymphoma can absolutely involve the liver without forming a discrete measurable mass.
Liver involvement by lymphoma frequently presents as diffuse infiltration without discrete nodules, and current guidelines explicitly recognize that liver size alone is not a reliable indicator of hepatic lymphoma involvement. 1
Key Diagnostic Principles
Guideline-Based Recognition
The Lugano Classification clearly states that "liver size by physical examination or CT scan is not a reliable measure of hepatic involvement by lymphoma" and that involvement is characterized by "diffusely increased or focal uptake, with or without focal or disseminated nodules" on PET-CT 1. This directly addresses your question—the liver can be involved without measurable masses.
Patterns of Hepatic Involvement
Lymphoma infiltrates the liver in several distinct patterns:
- Diffuse infiltration without mass effect (most common presentation)
- Homogeneous pattern on imaging without discrete masses 2
- Portal-based infiltration with atypical cells scattered throughout 2
- Miliary lesions or focal nodular lesions (less common) 1
Clinical Presentation Without Masses
Patients commonly present with hepatic dysfunction, elevated liver enzymes, fever, and jaundice—without any palpable lymphadenopathy or discrete hepatic masses 2. Imaging studies in these cases reveal homogeneous liver involvement rather than focal lesions. This presentation is particularly associated with:
- T-cell lymphomas (50% of cases in one series) 2
- B-cell lymphomas (50% of cases) 2
- T-cell/histiocyte-rich B-cell lymphoma (distinctive portal infiltration pattern) 3
Critical Diagnostic Pitfalls
The Mass Effect Misconception
Areas of liver hypoattenuation without mass effect are typically assumed to represent benign conditions like focal fatty infiltration, but lymphoma can present exactly this way 4. This is a dangerous diagnostic trap that can delay recognition.
Imaging Limitations
Early autopsy studies demonstrated that CT examination failed to detect hepatic lymphoma in 4 of 5 pathologically confirmed cases because the involvement was minimal or confined to periportal regions 5. Even when present, only cases with multiple nodules larger than "the tip of a thumb" were correctly diagnosed by CT 5.
Modern Diagnostic Approach
PET-CT is Essential
FDG-PET/CT is the gold standard for detecting diffuse hepatic involvement 1. It identifies:
- Diffusely increased uptake throughout the liver
- Focal areas of abnormal uptake even without corresponding CT masses 4
- Patterns that distinguish lymphoma from inflammatory conditions
Ultrasound Findings
In peripheral T-cell lymphoma specifically, look for hypoechoic periportal cuffing on ultrasound combined with lymphocytosis and hepatomegaly—this triad suggests hematologic malignancy even without masses 6.
When Biopsy is Needed
If PET-CT shows diffuse hepatic uptake but no discrete mass for tissue diagnosis:
- Transjugular liver biopsy is preferred when coagulopathy is present 7
- EUS-guided tissue acquisition is a safe alternative 8
- Portal-based infiltration patterns may mimic inflammatory liver disease histologically 3
Prognostic Implications
Hepatic involvement without peripheral lymphadenopathy indicates extensive disease with aggressive behavior 2. In one series, 11 of 16 patients died within 2 days to 31 months of diagnosis 2. This underscores the importance of recognizing diffuse hepatic involvement early, even without masses.
Response Assessment
For response evaluation, the revised criteria specify that hepatic involvement is assessable even when no measurable disease is present 9. Post-treatment assessment relies on:
- Resolution of diffuse FDG uptake on PET-CT
- Normalization of liver function tests
- Not on changes in liver size or resolution of masses
The absence of a discrete hepatic mass does not exclude lymphoma involvement—in fact, diffuse infiltration is a well-recognized and clinically significant pattern that requires PET-CT for detection 1, 2, 4.