Track: Case Reports

Topic: Other

Abstract:

Chronic myelomonocytic leukemia (CMML) is a hematopoietic stem cell neoplasm displaying myelodysplastic and myeloproliferative features. Approximately 10% of patients have cutaneous involvement. This is critical to recognize, as cutaneous involvement is associated with disease progression and an increased incidence of transformation to acute myeloid leukemia (AML). We present an 82-year-old male with a past medical history of squamous cell carcinoma, basal cell carcinoma, and melanoma presenting with a progressively enlarging papule on the right side of the neck. A shave biopsy was performed, which revealed a dense histiocytic infiltrate in the dermis with the immunohistochemical expression of CD3, CD4, CD68, S100, and CD1a while negative for langerin. These findings were compatible with an intermediate dendritic cell tumor. Considering the rarity of this entity, bone marrow analysis was recommended. Peripheral blood showed leukocytosis with monocytosis and thrombocytopenia. The bone marrow showed a hypercellular marrow with myeloid predominant trilineage hematopoiesis and megakaryocyte dysplasia. The cytogenetics study showed abnormal loss of the Y chromosome. Next-generation sequencing (NGS) identified mutations in NRAS and TET2. These mutations, along with the bone marrow findings, are consistent with Chronic myelomonocytic leukemia- Myeloproliferative subtype, CMML-MP-1. Awareness of this rare cutaneous manifestation as a presenting feature of CMML will aid in accurate diagnosis. This case also underscores the importance of systemic evaluation and molecular analysis in establishing these diagnoses.

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Sarika Jain, MD