What is the most likely diagnosis for a 55-year-old man with a firm cervical lymph node showing a specific immunophenotype?

• A. Diffuse large B-cell lymphoma
• B. Follicular lymphoma
• C. Nodal marginal zone lymphoma
• D. Precursor B-cell lymphoblastic lymphoma

Answer: (B)

In this scenario, the most likely diagnosis of follicular lymphoma is supported by the immunophenotype typically associated with this condition. Follicular lymphoma is a type of non-Hodgkin lymphoma characterized by the presence of neoplastic follicles in lymphoid tissue and commonly presents with painless lymphadenopathy, particularly in older adults.

The immunophenotype for follicular lymphoma usually involves the expression of B-cell markers such as CD19, CD20, and CD10, along with the co-expression of BCL2 protein due to the translocation involving the BCL2 gene, which plays a key role in the pathology of this lymphoma by inhibiting apoptosis. The combination of these markers helps to distinguish follicular lymphoma from other types of lymphomas.

In contrast, other lymphoma types mentioned differ in their immunophenotypic profiles or their clinical presentation. For instance, diffuse large B-cell lymphoma typically shows a more aggressive behavior and a different immunophenotype with a predominance of surface immunoglobulin and often lacks the distinct follicular architecture. Marginal zone lymphoma has its unique features and arises from marginal zone B-cells, presenting different clinical characteristics and markers. Precursor B-cell lymphoblastic lymphoma would typically present in a much younger demographic and exhibit features