Answers to Case 1-1-6
1. Figuree 1-1-6.1a,b are CT images showing poorly-enhancing soft tissue encasing
both kidneys without parenchymal compression. There are no distinct renal
masses seen, but the parenchymal enhancement pattern is irregular. Enlarged
para-aortic lymph nodes are also seen.
2. These images demonstrate one of the described patterns of renal lymphoma,
others relate to the different mechanisms of spread to the kidneys.
• The most common CT manifestation (in 40–60%) is shown in Fig. e 1-1-6.2a–c ,
with multiple bilateral ball-shaped renal masses which refl ects haematogenous
dissemination.
• Solitary masses are less common (10–20%).
• Contiguous invasion from retroperitoneal tissues (in 30%) is highly characteristic
of renal lymphoma – typically a large, bulky retroperitoneal mass encases
the renal vasculature and invades the renal hilum and parenchyma. Patients
commonly present with hydronephrosis. This can be mimicked by retroperitoneal
fi brosis.
• Diffuse infi ltrative disease (20%) is associated with lymphomatous proliferation
within the interstitium of the kidney, which presents as global renal
enlargement, with preservation of renal contour. This diagnosis is often subtle
and may manifest as insidious loss of renal function.
• Perirenal lymphoma as seen in Fig. 2 .18.1a,b , in the absence of retroperitoneal
nodes or parenchymal involvement is rare. This can present a diagnostic
diffi culty as rarely retroperitoneal fi brosis and extra-medullary haemopoiesis
can present with similar CT fi ndings.
3. The diagnosis is lymphoma with a poor prognosis as renal involvement usually
indicates disseminated disease. Although only 3–8% of patients with lymphoma
have CT evidence of renal involvement autopsy studies demonstrate infi ltration
in 34–68% of such patients. Primary renal lymphomas are rare and of these post
transplant lymphoproliferative disorder is most frequently seen, thought to be the
result of EBV infection during immunosuppressive therapy.