Splenic non-Hodgkin's lymphoma presenting as recurrent kidney stones -- an "incidentaloma"?

Splenic lymphoma, or primary malignant lymphoma of the spleen (PMLS), is an uncommon condition whose true nature is difficult to define due to the variable ways it has been classified. Out of all non-Hodgkin's lymphomas it comprises less than 2% of cases. Some experts suggest that PMLS only involves the spleen and splenic hilum, while others consider PMLS to be an entity that develops within the spleen and later has the potential for invading adjacent organs and metastasizing. Clinical features of splenic lymphoma are characterized by nonspecific systemic symptoms such as low grade fevers, night sweats and symptoms related to considerable splenomegaly. Most of these lymphomas are of B-cell origin showing low or intermediate-grade lymphoma on histological analysis. The case we present here is of a patient presenting with left sided flank pain, and given a previous history of nephrolithiasis, a presumably simple diagnosis of kidney stones was made. However, further investigation led to the discovery of splenic lymphoma, which was asymptomatic earlier but may have manifested symptoms that mimicked renal colic.