Primary non-Hodgkin's lymphoma of the liver: sonographic and CT findings.

Background: A preoperative diagnosis of primary hepatic lymphoma (PHL) can have profound therapeutic and prognostic implications. Because of the rarity of PHL, however, there are few reports on diagnostic imaging. We reviewed the clinical and radiologic findings of 29 patients with PHL, the largest series to date, to evaluate the diagnostic features of this disease.

Methods: Clinical data and radiologic findings at presentation were retrospectively reviewed for 29 patients with pathologically confirmed PHL from January 2005 to June 2013. Imaging studies, including ultrasound (US) (n=29) and contrast-enhanced computed tomography (CECT) (n=24), were performed within 2 weeks before biopsy or surgery.

Results: Among the 29 patients, 23 (79%) were positive for hepatitis B virus (HBV) and 26 (90%) had a significantly elevated level of serum lactate dehydrogenase (LDH). There were two distinct types of PHL on imaging: diffuse (n=5) and nodular (n=24). Homogeneous or heterogeneous hepatomegaly was the only sign for diffuse PHL on both US and CECT, without any definite hepatic mass. For the nodular type, 63% (15/24) of patients had solitary lesions and 38% (9/24) had multiple lesions. On US, seven patients displayed patchy distribution with an indistinct tumor margin and a rich color flow signal. CECT showed rim-like enhancement (n=3) and slightly homogeneous or heterogeneous enhancement (n=14) in the arterial phase and isoenhancement (n=5) and hypoenhancement (n=12) in the portal venous and late phases. Furthermore, in five patients, CT revealed that hepatic vessels passed through the lesions and were not displaced from the abnormal area or appreciably compressed.

Conclusions: The infiltration type of PHL was associated with the histologic subtype. Considered together with HBV positivity and elevated LDH, homogeneous or heterogeneous hepatomegaly may indicate diffuse PHL, whereas patchy distribution with a rich color flow signal on US or normal vessels extending through the lesion on CECT may be the diagnostic indicators of nodular PHL.