Sections of the “submental mass” reveals a reactive lymph node with follicular and paracortical zone hyperplasia, foci of monocytoid B-cell hyperplasia, and sheets/large clusters of epithelioid histiocytes some which encroach upon germinal centers.

The nodal architecture has been largely replaced by thick fibrotic bands and nodular lymphoid tissue, which contains classic Reed- Sternberg cells and their variants which possess the typical CD15+/CD30+/CD20-/CD45- immunophenotype. There are foci where the Reed-Sternberg cells and variants form large sheets and clusters, invoking a syncytial histologic pattern.

Antibody Result (neoplastic follicles)
CD20:  positive
CD3: negative
CD5: negative
CD23: negative
CD10:  positive
Bcl-1 (Cyclin D1): negative
Ki- 67: Low proliferation index 10%
Bcl-6: positive

Immunoglobulin-bcl-2 Translocation Present

This lymph node biopsy reveals extensive zonal necrosis, which is sharply demarcated from surrounding reactive lymphoid tissue that is rich in activated histiocytes and immunoblasts that are contiguous with the necrosis. Histochemistry studies for fungal and acid-fast organisms are negative. Evidence of malignancy is not identified. 

H&E sections of the lymph node demonstrate a nodular/follicular architecture with packed neoplastic follicles, and focal extension of the lymphoid infiltrate into perinodal soft tissues. The neoplastic nodules lack normal germinal centers, germinal center polarization and tingible-body macrophages. No diffuse areas are appreciated (entire node submitted for microscopic examination). Most of the neoplastic cells within nodules/follicles are small-intermediate sized, have extremely scant cytoplasm, convoluted/folded nuclei with condensed irregular chromatin pattern, and mostly indistinct nucleoli. Approx. 17 centroblasts/per high-power field are noted. Immunohistochemistry (to highlight immunoarchitecture) shows that the neoplastic follicles are positive for CD20, Bcl-2, CD10, and Bcl-6. The Ki-67 proliferation index within neoplastic follicles averages 50-60% which is concordant with morphologic grade. Flow cytometric analysis detects 61% CD19+/CD20+ B-cells co-expressing CD10 and demonstrating surface Ig kappa light-chain restriction. 

The slides show a well-circumscribed multinodular infiltrate of intermediate to large-sized cells involving the dermis and subcutaneous adipose tissue and separated from the overlying epidermis by a Grenz zone. The lesion cells exhibit striking pleomorphism, including numerous centroblast-like forms admixed in a background of cleaved to almost sarcomatoid spindled centrocyte like forms. The infiltrate is arranged in large vaguely-defined ovoid nodules oriented perpendicularly to the epidermis. While scattered aggregates of small lymphocytes are admixed throughout, mantle cuffs are not conspicuous. Immunohistochemistry reveals the lesional cells express Pax-5, along with weak BCL-6, and patchy weak CD10. A subset of the lesional cells expresses BCL-2, but the majority (~70-80%) appears negative. MUM-1 highlights scattered cells, but appears largely negative in the lesional population. A CD21 immunostain highlights scattered nodular fragments of follicular dendritic cell meshworks.

Cases provided by Dariusz Stachurski, MD, digitized by Arlen Brickman, MD, and organized, and uploaded by Fazilet Yilmaz, MD.