Chronic Atypical Myelomonocytic Leukemia of Eosinophilic Lineage in a Cat With Feline Leukemia Virus: A First Case Report.

Feline hematopoietic neoplasms associated with retroviruses pose a diagnostic and therapeutic challenge, especially when they present with atypical morphological features that do not fit conventional classifications. This work describes the first reported case worldwide of atypical chronic myelomonocytic leukemia of eosinophilic lineage in a cat positive for feline leukemia virus, diagnosed through detailed cytomorphological analysis and the use of enzymatic cytochemical stains. The rarity of this case underscores the importance of documenting and studying uncommon presentations, with the goal of expanding clinical knowledge and strengthening diagnostic tools in feline veterinary medicine.