PT  - JOURNAL ARTICLE
AU  - Benny Man Wai Lit
AU  - Yok Lam Kwong
AU  - Kit Fai Wong
TI  - Immunohistochemical detection of cytoplasmic nucleophosmin in formalin-fixed paraffin-embedded marrow trephine biopsies in acute myeloid leukaemia
AID  - 10.1136/jclinpath-2015-203175
DP  - 2016 May 01
TA  - Journal of Clinical Pathology
PG  - 409--414
VI  - 69
IP  - 5
4099  - http://jcp.bmj.com/content/69/5/409.short
4100  - http://jcp.bmj.com/content/69/5/409.full
SO  - J Clin Pathol2016 May 01; 69
AB  - Aims Nucleophosmin (NPM1) gene mutations resulting in cytoplasmic delocalisation of nucleophosmin (NPMc+) are the most common genetic abnormality in acute myeloid leukaemia (AML). In this study, we tested whether immunohistochemical (IHC) detection of cytoplasmic NPM1 (cNPM1) in formalin-fixed bone marrow trephine biopsies correlated with NPM1 mutations and the prognostic impact of NPM1 and fms-related tyrosine kinase 3-internal tandem duplication (FLT3-ITD) gene mutations was also assessed.Methods A total of 71 Chinese adult de novo AML cases were evaluated for cNPM1 by IHC where the bone marrow trephines were fixed in 10% buffered formalin and decalcified by 5% EDTA. NPM1 and FLT3-ITD gene mutations were also investigated using PCR, fragment analysis and direct DNA sequencing.Results IHC analysis of cNPM1 had a very good sensitivity (86.7%) and excellent specificity (96.4%) for NPM1 mutation. The positive predictive value was 86.7% and the negative predictive value was 96.4%. NPM1 mutations and FLT3-ITD were closely associated (p=0.003). Patients with mutated NPM1 and without FLT3-ITD mutation have a longer overall survival (p=0.042) than patients with both NPM1 and FLT3-ITD mutations.Conclusions Our results showed that IHC detection of cNPM1 in formalin-fixed trephine biopsies correlated well but not entirely with NPM1 mutation. Furthermore, NPM1 mutations were significantly more frequent in FLT3-ITD than FLT3-wild-type cases.