Anaplastic large cell lymphoma (ALCL) expressing nuclear ALK protein with a paranuclear dot pattern carries the translocation:

• A t(2;17)(p23;q25) — CLTC-ALK fusion
• B t(1;2)(q25;p23) — TPM3-ALK fusion
• C t(2;5)(p23;q35) — NPM1-ALK fusion ✓
• D Inv(2)(p23;q35) — ATIC-ALK fusion

Explanation

The t(2;5)(p23;q35) NPM1-ALK translocation is the most common (~75% of ALK+ ALCL) and produces a fusion protein that localizes to both the nucleus and cytoplasm (nuclear dot + diffuse cytoplasmic pattern) due to the nuclear export signal of NPM. The other variant translocations (CLTC-ALK, TPM3-ALK, ATIC-ALK) produce different ALK staining patterns (granular cytoplasmic, cytoplasmic only, etc.) and are collectively less common. ALK+ ALCL has significantly better prognosis than ALK- ALCL.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.