A 62-year-old man presents to the clinic with a 3-month history of a rapidly enlarging mass in his right groin. He also reports intermittent fevers and a 15-lb weight loss. Past medical history is significant for hyperlipidemia which is managed with atorvastatin. Physical examination reveals a 5-cm, non-tender, fixed right inguinal lymph node and several smaller palpable nodes in the axillary region. There is no hepatosplenomegaly. An excisional biopsy of the inguinal node shows sheets of large lymphoid cells with prominent nucleoli and a high mitotic index. Immunophenotyping is positive for CD19, CD20, and BCL6.
Which of the following is the most likely diagnosis?
The correct answer is:
B) Diffuse large B-cell lymphoma (DLBCL)
Non-Hodgkin Lymphoma (NHL) is a heterogeneous group of malignancies of B-cells (85%), T-cells, or NK-cells. Unlike Hodgkin lymphoma, NHL typically presents with non-contiguous nodal spread and a higher frequency of extranodal involvement (e.g., gastrointestinal tract, skin, central nervous system). DLBCL is the most common form of NHL in adults. It typically presents in older patients as a rapidly enlarging symptomatic mass (nodal or extranodal). Histology shows diffuse sheets of large B-cells, at least 3–4 times the size of a resting lymphocyte, that obliterate the normal lymph node architecture.
Answer choice A: Burkitt lymphoma, is incorrect. While Burkitt lymphoma also grows rapidly and presents with B-symptoms, histology would show a "starry sky" appearance (tingible body macrophages among small-to-intermediate malignant B-cells). It is strongly associated with the t(8;14) translocation of the c-myc gene.
Answer choice C: Follicular lymphoma, is incorrect. This is an slow-growing lymphoma that presents with painless waxing and waning lymphadenopathy. Histology shows nodular/follicular aggregates rather than diffuse sheets, and it is characterized by the t(14;18) translocation involving BCL2.
Answer choice D: Mantle cell lymphoma, is incorrect. This aggressive B-cell lymphoma typically presents in older men with lymphadenopathy and often involves the gastrointestinal tract (lymphomatous polyposis). It is defined by the t(11;14) translocation involving Cyclin D1.
Answer choice E: Mycosis fungoides, is incorrect. This is a T-cell lymphoma of the skin. It presents with cutaneous plaques or patches characterized by Pautrier microabscesses, which are intraepidermal clusters of neoplastic T-cells.
Key Learning Point
Diffuse large B-Cell lymphoma (DLBCL) is the most common and aggressive adult NHL. It presents with rapidly enlarging nodes and B-symptoms. It is a mature B-cell neoplasm (CD19+, CD20+) that is generally treated with the R-CHOP chemotherapy regimen (Rituximab, Cyclophosphamide, Hydroxydaunorubicin, Oncovin, Prednisone).
