Imaging of a secondary hepatic lymphoma

Clinical History

September 2002: right nephrectomy because of a renal cell carcinoma. CT did not detect tumour recurrence or metastases over an 8-year period follow-up.
November 2012: hospitalization for hepatomegaly and hepatic insufficiency rapidly worsening. Blood chemistry revealed increased levels of hepatic enzymes; complete blood count was normal.

Imaging Findings

Abdominal US: multiple solid hypoechoic nodules of the liver (Fig. 1).

CE-CT: hypoattenuating nodules, bulging the hepatic contours, are appreciable in the venous phase; slightly enlarged paraaortic and mesenteric lymph nodes are present (Fig. 2a-d). The spleen is normal.

3T-MRI: hepatic nodules are hypointense on T1W-images and hyperintense on T2W-images (Fig. 3a-c), with restricted water diffusion on DWI (Fig. 4a-d). Nodules are hypovascular after intravenous Gd-BOPTA injection (5a, b); some nodules show a central pooling of the contrast medium in the late venous and hepatobiliary phases (Fig. 5c, d).

Histology of a specimen from a hepatic percutaneous US-guided biopsy: diffuse and sinusoidal involvement of the liver by a proliferation of large blasts (Fig. 6 a, b) positive for the B-cell marker CD20 (Fig 6 c). The immunohistochemical examination additionally reveals positivity for CD10 and absence of the T-cell surface antigens CD3 and CD5. The proliferative activity with Ki-67 was high (80%).

Discussion

Extranodal lymphoma describes a non-Hodgkin lymphoma (NHL) or a Hodgkin disease (HD) involving sites other than the lymph nodes [1, 2]; it mostly affects patients with NHL, recurrent disease or immunodeficient subjects [1, 2]. Extranodal lymphoma can be primary (confined to a single organ without/with involvement of hilar nodes or surrounding fat) and secondary (involvement of distant nodes, bone marrow) [2].
Primary hepatic lymphoma is extremely rare, while secondary involvement is relative common in advanced stages; hepatic HD is consistently associated to a splenic localization [1, 2].
Alike other solid organs, primary and secondary hepatic lymphomas are indistinguishable by imaging and share similar patterns (diffuse, focal or multifocal). Diffuse hepatic involvement is usually undetected with anatomic imaging because of the lack of remarkable findings [1-4]. Large hepatic masses are more common in primary lymphoma, whereas discrete nodules (sometimes in a military pattern) are more typical of a secondary involvement [2, 4, 5].
Lymphomatous hepatic nodules are hypoechoic on US images, sometimes with a bull-eye appearance; larger masses are usually inhomogeneous [1-6]. CT shows hypoattenuating nodules with somewhat enhancement after intravenous contrast administration; calcifications may be occasionally detected. Larger masses may be necrotic [1-5]. Nodules are hypointense on T1W-MRI and hyperintense on T2W-MRI, and, similarly to CT findings, they are hypovascular on contrast enhanced MRI [1, 2, 4]. In the present case some nodules showed a central pooling of the liver-specific contrast medium in the late venous phase and in the hepatobiliary phase, a finding never previously reported, which can be likely related to regressive changes. As other high cellularity lesions, lymphomatous nodules exhibit restricted water diffusion on DWI.
In the absence of lymphadenopathies or a known disease or other localizations, the diagnosis of a hepatic lymphoma is not amenable with anatomic imaging, and percutaneous biopsy is mandatory for tissue characterization.

Differential Diagnosis List

Final Diagnosis

Secondary hepatic non-Hodgkin lymphoma

URL:	https://www.eurorad.org/case/10619
DOI:	10.1594/EURORAD/CASE.10619
ISSN:	1563-4086