Diagnostic utility of immunohistochemistry in detection of NPM1 mutations in acute myeloid leukemia with a patchy distribution.

Nucleophosmin 1 ( NPM1 ) mutations occur in approximately one-third cases of adult de novo acute myeloid leukemia (AML). Identification of NPM1 mutations is important for classification, risk stratification, tailored therapy, and monitoring minimal residual disease. Mutational analysis is widely used for detecting NPM1 mutations. Immunochemistry assessing abnormal cytoplasmic localization of NPM1 protein has been used as a surrogate marker for NPM1 mutations. We present a case of AML with mutated NPM1 that was missed by sequencing analysis but detected by immunohistochemistry. This case highlights the value of immunohistochemistry in identifying NPM1 mutations in a subset of AML cases.
Competing Interests: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported.
(© 2024 The Authors. eJHaem published by British Society for Haematology and John Wiley & Sons Ltd.)