A 64-year-old man has leukocytosis and generalized lymphadenopathy. Flow cytometry of blood shows CD19-positive cells with strong surface immunoglobulin, CD5 positivity, CD23 negativity and CD200 negativity. Node biopsy shows nuclear cyclin D1 expression. The underlying molecular lesion responsible is:

• A del(17p) involving TP53
• B Trisomy 12
• C t(11;14)(q13;q32) leading to cyclin D1 overexpression ✓
• D t(14;18) leading to BCL2 overexpression

Explanation

Strong surface immunoglobulin with CD5 positivity but CD23 and CD200 negativity distinguishes mantle cell lymphoma from chronic lymphocytic leukaemia, and nuclear cyclin D1 overexpression from t(11;14)(q13;q32) is the defining lesion; SOX11 supports the diagnosis when cyclin D1 is negative. Trisomy 12 occurs in CLL and predicts intermediate risk, and TP53 deletion does not drive cyclin D1 expression.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.