Real world implementation of flow cytometric monocyte subset partitioning for distinguishing chronic myelomonocytic leukaemia from other causes of monocytosis.

Monocyte subset partitioning by flow cytometry may be a useful tool in distinguishing chronic myelomonocytic leukaemia (CMML) from other causes of monocytosis, however there has been varying success in real world implementation. Additionally, current assays require an individual tube for analysis despite significant overlap in antibodies used in routine T and NK cell analysis. The objective of this study was to validate a flow cytometry assay for the enumeration of monocyte subsets in our community-based laboratory and compare this to a hybrid panel allowing analysis of monocytes, T cells and NK cells in a single tube. Monocyte subset analysis was performed on peripheral blood samples of patients with monocytosis at the time of bone marrow biopsy or transient monocytosis in the setting of bacteraemia. Cut-offs of >94% classical and <1.13% non-classical monocytes for distinguishing CMML were assessed. Classical monocytes were significantly higher, and non-classical monocytes significantly lower in CMML compared to other causes of monocytosis. The sensitivity and specificity of >94% classical monocytes were 73% [95% confidence interval (CI) 43-90%] and 89% (95% CI 75-96%) regardless of which panel was used. Non-classical monocytes of <1.13% had a sensitivity and specificity of 82% (95% CI 52-97%) and 83% (95% CI 68-92%) with the monocyte panel and 55% (95% CI 28-78%) and 89% (95% CI 75-96%) using the hybrid panel. We have found the estimation of the classical monocyte subset to be the most robust and repeatable variation of this assay with sensitivity and specificity that is clinically useful. A hybrid panel may provide an effective approach to implementing monocyte subsets into practice.

Transient immune-mediated agranulocytosis following Mycoplasma pneumoniae infection.

Mycoplasma pneumoniae is a common respiratory pathogen which may cause haematological manifestations including haemolytic anaemia and thrombocytopaenia. Severe neutropaenia is rare with very few cases reported in the literature. An 85-year-old man was transferred to our facility with agranulocytosis in the context of an infective exacerbation of chronic obstructive pulmonary disease with positive serological testing for M. pneumoniae. No alternative infective, autoimmune or lymphoproliferative cause of the neutropaenia was identified. Granulocyte autoantibody testing was performed with a positive result for neutrophil-bound IgG and IgM autoantibodies and significant agglutination reactions. The patient was treated with azithromycin and granulocyte colony-stimulating factor which resulted in a sustained resolution of his neutropaenia.

Novel Mutations Resulting in a Moderate to Severe Phenotypic Manifestation of Hemophilia A in a Female.

Hemophilia A is an X-linked, recessive disorder resulting from mutations in the f8 gene. Here we report the rare case of a female compound heterozygote with mild factor VIII deficiency (fVIII:C 9%) and moderate phenotype. On investigation she was confirmed to have normal Von Willebrand factor studies with a 46XY genotype. Further genetic testing revealed 3 mutations in the f8 gene: 1 novel missense mutation (c.6142T>G), 1 novel in-frame deletion (c.1281_1292del), and another missense mutation of unclear significance (c.3780C>G). Both parents had normal coagulation profiles; however, the 2 novel mutations were present in the patient's mother and the known missense mutation was present in her father. This unusual case demonstrates the utility in genetic analysis for f8 gene mutational analysis and suggests a compound effect of the 3 identified mutations as a cause for factor deficiency.