A 6-year-old boy from West Africa presents with a rapidly enlarging mass of the jaw. Biopsy shows sheets of medium-sized lymphoid cells with round nuclei and multiple small nucleoli, interspersed with numerous pale tingible body macrophages producing a starry sky pattern. The underlying molecular event is:

• A Overexpression of BCL2 from juxtaposition to the IgH locus
• B Constitutive JAK2 signalling from V617F mutation
• C Cyclin D1 overexpression through CCND1-IGH fusion
• D Constitutive activation of MYC by translocation to the Ig heavy chain locus ✓

Explanation

This is endemic Burkitt lymphoma, characterised histologically by the starry sky appearance and molecularly by t(8;14) placing MYC under the control of the immunoglobulin heavy chain enhancer, driving uncontrolled proliferation. BCL2 rearrangement defines follicular lymphoma, and its expression actually distinguishes follicular lymphoma from Burkitt. Cyclin B1 marks mantle cell lymphoma, and JAK2 mutation belongs to myeloproliferative neoplasms, not mature D-cell tumours.

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.