[Acute myeloid leukemia with inversion of chromosome 16: cytological, immunophenotypic and cytogenetic disruption]. / Leucémie aiguë myéloïde avec inversion du chromosome 16 : discordance cytologique, immunophénotypique et cytogénétique.

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.

Skeletal Myopathy as the Initial Manifestation of Light Chain Multiple Myeloma.

Monoclonal gammopathies due to plasma cell dyscrasias can cause various rare neuromuscular disorders. The peripheral nervous system is most commonly affected, while muscle diseases associated with monoclonal gammopathies are rare. Skeletal myopathy, as a manifestation in the context of multiple myeloma, is extremely uncommon and is usually the result of immunoglobulin light chain (AL) amyloidosis deposits in the muscles. Here we present an atypical case of a patient with generalized myopathy as the presenting manifestation of light chain multiple myeloma. Interestingly, muscle involvement in our case was not the consequence of AL amyloidosis deposits but rather due to non-amyloid light chain deposition disease associated with light chain multiple myeloma. LEARNING POINTS: Light chain multiple myeloma can present as myopathy.Creatine kinase and muscle biopsy specimens only examined using routine stains can be normal in this condition.