Don’t Miss the Low Grade Component in the Background: Diffuse Large B-Cell Lymphoma Arising from Low Grade Follicular Lymphoma

Lessons From the Friday Unknowns

Histologic sections of a lymph node excisional biopsy specimen show enlarged lymph nodes extensively replaced by lymphoma with a low grade and a high grade component:

Most of the lymph nodes are replaced by diffuse large B-cell lymphoma. The neoplasm has a partial starry sky appearance and is composed of large cells with vesicular nuclear chromatin. Apoptosis is abundant and mitotic figures are easily identified.

The second component is follicular lymphoma which is low-grade and composed of a mixture of centrocytes and centroblasts supporting grade 1–2.

Both the diffuse large B-cell lymphoma and the follicular lymphoma are positive for CD10, CD20, BCL–2 and BCL–6, and are negative for MYC. The antibody specific for Ki-67 shows a proliferation rate of approximately 95% in the diffuse large B-cell lymphoma and 5–10% in the follicular lymphoma.

This case highlights the importance of not missing the low grade component at the edges while assessing the more obvious aggressive component.

Link to digital slides | Slides labeled case 3: https://bit.ly/3vpFDjq