Intravascular large B-cell lymphoma presenting as cholecystitis and pancytopenia: case report with literature review.

Intravascular large B-cell lymphoma (IVLBCL) is a rare variant of extranodal diffuse large Bcell lymphoma with only a few more than 300 cases reported. It is characterized as lymphoma cells confined to the lumina of small vessels, so patients usually do not present with masses or lymphadenopathy. Clinical presentations of these patients are non-specific and the pathologic changes may be subtle, which often leads to delayed diagnoses and, in many instances, a postmortem diagnosis. IVLBCL can essentially involve the vessels of any organ, but it is quite rare for the gallbladder to serve as the initial presenting site; there are only four such cases reported in the English literature. Furthermore, IVLBCL of the gallbladder with peripheral blood involvement is even less common. We report a recent case of IVLBCL presenting as acute cholecystitis and pancytopenia. The patient underwent a simple cholecystectomy. Examination of the gallbladder showed clusters of large lymphoma cells within lumina of small vessels in the gallbladder wall. These cells were positive for CD5/CD20 and negative for CD3, CD10, and TdT. Based on these findings, a diagnosis of IVLBCL was made. Coincidently, circulating lymphoma cells were identified in the peripheral blood and confirmed by flow cytometric analysis (positive for CD19/CD20/CD5, without light chain expression). The patient was started on chemotherapy but subsequently died of chemotherapy related multi-organ failure 10 days after the initial diagnosis.

Intravascular large B-cell lymphoma: report of three cases and analysis of the mTOR pathway.

Intravascular large B-cell lymphoma (IVLBCL) is a rare, aggressive and often fatal non-Hodgkin lymphoma characterized by preferential growth of malignant B-cells within the lumina of small vessels. Rituximab plus anthracycline-based chemotherapy is the current standard regimen for IVLBCL, however it has minimal efficacy in relapsed or refractory diseases. Recent clinical trials have shown a significant anti-lymphoma activity of mammalian target of rapamycin (mTOR) inhibitors in relapsed and refractory diffuse large B-cell lymphoma (DLBCL); however, the activation status of the mTOR pathway and the therapeutic potential of mTOR inhibitors in IVLBCL have not yet been studied. Here we described the clinicopathological features of 3 cases of IVLBCL diagnosed at our institutions, and evaluated the activation status of the mTOR signaling in these tumors. Our results showed that the mTOR complex 2 pathway was selectively upregulated in IVLBCL, as evidenced by a predominant nuclear localization of the activated form of mTOR (p-mTOR at Ser2448) with concomitant overexpression of nuclear p-Akt (Ser473) and vascular endothelial growth factor (VEGF)-A in the lymphoma cells. These data suggest that overactivation of mTOR pathway may play a role in lymphomagenesis of IVLBCL and mTORC2 inhibitors may be beneficial in treating IVLBCL.