Fluroscence in-situ hybridization negative PML/RARA: A cryptic puzzle

Abstract

Acute promyelocytic leukemia (APL) has defined biology and clinical course that is, distinct from the other forms of acute myelogenous leukemia. It may present with potentially devastating coagulopathy and the sensitivity to retinoid differentiating agents, including all-trans retinoic acid and arsenic trioxide, hence a fast and definite diagnosis is imperative. Reciprocal 15, 17 translocation creates a PML/RARA fusion gene on the derivative chromosome 15, which can be detected by various molecular tests such as cytogenetics, fluroscence in-situ hybridization (FISH), reverse transcriptase-polymerase chain reaction. We present here a diagnostically challenging case, both morphologically and immunophenotypically proven to be APL, which was negative for the PML/RARA by FISH.

Keywords

• Acute promyelocytic leukemia
• fluorescence in-situ hybridization
• PML/RARA