Primary cardiac lymphoma: molecular cytogenetic characterization of a rare entity

The majority of cardiac atrial neoplasms represent benign myxomas. Rarely, malignant cardiac neoplasms are encountered and can include primary cardiac neoplasms, as well as secondary tumors involving the heart. As many cardiac neoplasms lack pathognomonic clinical features, histopathologic diagnosis is crucial for classification and appropriate treatment of these neoplasms. Molecular investigation is critical to begin to catalogue genomic changes that correlate with these malignancies.

A 60-year-old man presented with superior vena cava syndrome, and computed tomographic scan revealed an infiltrative mass of the right atrium that nearly filled the atrial chamber and partially occluded superior vena cava flow. Urgent surgical resection revealed a soft mass with the appearance of "fish flesh." Histologic, immunochistochemical, cytogenetic, and detailed molecular investigations were carried out.

Histologic examination revealed complete replacement of the atrial wall by diffuse sheets of pleomorphic lymphoid cells with occasional smaller plasmacytoid cells. The predominant lymphoid population was immunoreactive for CD45, CD20, CD79a, BCL-2, BCL-6, Ki-67, CD10, p53, and light chain restricted for IgM lambda. A diagnosis of primary cardiac diffuse large B-cell lymphoma with plasmacytoid differentiation was established and was supported by cytogenetic studies demonstrating the presence of a t(14;18)(q32;q21) translocation in addition to other chromosomal abnormalities. Fluorescence in situ hybridization revealed no evidence of a C-MYC translocation.

In this single case, comparative genomic hybridization analysis using both bacterial artificial chromosome and oligonucleotide arrays correlated well with cytogenetic findings and allows for the cataloguing of more subtle genomic events.