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- leukemic progenitor cells
- myeloid leukemias and dysplasia
- myeloproliferative disorders
- molecular genetics
- monocyte and macrophage biology
Cutaneous involvement by a myeloid neoplasm (myeloid leukaemia cutis), such as chronic myelomonocytic leukaemia (CMML) or acute myeloid leukaemia (AML), can show a spectrum of morphological features and maturation stages, with occasional evidence of histiocytic/dendritic cell differentiation.1 This has to be distinguished from de novo or clonally unrelated histiocytic/dendritic cell neoplasms, which may also arise in patients with underlying myeloid neoplasms. Here, we describe a patient with myeloid leukaemia cutis showing mixed histiocytic and Langerhans cell differentiation arising from underlying CMML/AML. This is an illustrative case of clonal evolution of a myeloid neoplasm that demonstrates at least three distinct constellations of clinical, pathological and molecular findings.
The patient is a 56-year-old man with a prior diagnosis of AML who now presents with a 5-month history of slowly progressive skin nodules. At the time of initial leukaemia diagnosis 10 months prior, the disease was characterised as AML, not otherwise specified with 80% myeloblasts (see legend of figure 1A for immunophenotype and cytochemical characterisation), background dysmegakaryopoiesis and a normal karyotype (figure 1A and B). A peripheral blood smear at the time was notable for a marked leucocytosis (white blood cell count 59.68 x 109/L) with 14% monocytes and 25% blasts, normochromic macrocytic anaemia (haemoglobin 9.0 g/dL, mean cell volume (MCV) 102.4 fL) with anisocytosis, and thrombocytopenia with unremarkable morphology (platelets 86 x 109/L). The only other available complete blood count (CBC) from 5 years prior was notable only for a platelet count of 106 x 109/L. Following standard induction and re-induction therapy, the patient appeared to be in morphological complete remission. One month after completion of induction therapy, CBCs revealed a persistent leucocytosis (up to 58.87 x 109/L) with monocytosis (up to 52%, 20.51 x 109/L), thrombocytopenia (50–90 x 109 …
Handling editor Mary Frances McMullin.
Contributors VS prepared the manuscript. EAM and ASK both diagnosed the case and were the primary editors of the manuscript. DJD provided critical clinical information and care of the patient.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Patient consent Not required.
Ethics approval Dana-Farber Cancer Center.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement No additional data are available.
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