Follicular Large B-Cell Lymphoma
Lesson From the Friday Unknowns
The patient has a history of low grade follicular lymphoma with progression to grade 3.
Histologic sections show needle shaped fragments of lymph node involved by lymphoma. The neoplasm has a vaguely nodular pattern with the follicles composed of a mixture of centrocytes and centroblasts supporting grade 3A. A diffuse component with large lymphoma cells are seen (representing at least 30% of the biopsy specimen).
Immunohistochemical studies show that the tumor cells are positive for CD20, CD10, BCL6, CD23 and BCL2 and are negative for CD3. The proliferation index measured by Ki-67 is up to 30%. CD21 highlights residual networks of follicular dendritic cells.
In summary, the findings are those of follicular lymphoma grade 3A with areas of diffuse large B cell lymphoma. FISH studies to assess for MYC, BCL2 and BCL6 gene rearrangements are in progress.
Link to digital slides: https://bit.ly/3rRwQ9F | Case 5