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Published on: April 15, 2022
[Acute myeloid leukemia with inversion of chromosome 16: cytological, immunophenotypic and cytogenetic disruption]
Safaa Mghinia1, Mohamed Zaidani2, Nazha Hda3
1Laboratoire d'hématologie, CHU Ibn Rochd, Casablanca, Maroc.
Abstract:
Acute myeloid leukemia (AML) with inv(16) is primarily associated with the eosinophilic LAM4 form belonging to the favorable prognosis group of AML. We report the case of an 18-year-old man with acute myeloid leukemia with unusual inversion of chromosome 16. Cytological, phenotypic and cytogenetic investigations showed a divergence from those in the literature. Indeed, the myelogram shows a medullary infiltration by elements blocked at the stage of myeloblates/promyelocytes, containing Auer rods grouped sometimes in fagots in blasts, promyelocytes and neutrophils. In view of this pathognomonic aspect, the diagnosis of AML type M3 is mentioned but quickly questioned by the results of immunophenotyping in favor of a maturing AML (M2). The karyotype and the FISH later objectify a recurrent anomaly "cytologically unexpected" inversion 16 (p13, q22) associated with trisomy 22.
Insights
This case study details an unusual presentation of acute myeloid leukemia (AML) with an inversion 16 chromosome abnormality. The findings challenge typical classifications, highlighting the complexity of AML diagnosis.
Area of Science:
- Hematology
- Cytogenetics
- Oncology
Background:
- Acute myeloid leukemia (AML) with inversion 16 (inv(16)) typically presents as the favorable-risk LAM4 subtype.
- This subtype is characterized by specific morphological and immunophenotypic features.
Observation:
- A rare case of AML with inv(16) in an 18-year-old male is presented.
- Cytological examination revealed Auer rods in various myeloid cells, initially suggesting AML M3 (acute promyelocytic leukemia).
- Immunophenotyping indicated a maturing AML (M2), contrasting with the initial cytological findings.
Findings:
- Karyotyping and fluorescence in situ hybridization (FISH) confirmed the presence of inv(16) (p13;q22) along with trisomy 22.
- These cytogenetic findings were unexpected given the initial morphological and phenotypic assessments.
- The combination of inv(16) and trisomy 22 in this context is not well-documented in existing literature.
Implications:
- This case underscores the importance of integrating comprehensive cytological, phenotypic, and cytogenetic data for accurate AML diagnosis.
- The unusual presentation challenges established diagnostic criteria and may necessitate re-evaluation of prognostic models for AML with inv(16).
- Further research is warranted to understand the clinical significance and biological underpinnings of this rare AML variant.
