What is the most likely diagnosis for a 79-year-old woman with pale skin, splenomegaly, and a high white blood cell count?

The clinical presentation of the 79-year-old woman suggests a likely diagnosis of chronic lymphocytic leukaemia (CLL). CLL commonly occurs in older adults and is characterized by the accumulation of mature, dysfunctional lymphocytes in the bloodstream, lymph nodes, and spleen, which corresponds with the findings of splenomegaly.

Pale skin in this context may be indicative of anemia, which can occur in CLL due to various mechanisms, including bone marrow infiltration and the effects of chronic illness. The elevated white blood cell count is a hallmark of CLL, where there is typically a significant increase in lymphocytes.

When considering the other options, acute myeloid leukaemia (AML) tends to present with more acute symptoms and often more severe cytopenias, making it less likely in this older age group featuring a more gradual presentation. Chronic myeloid leukaemia (CML) is also a consideration but typically presents with a marked increase in myeloid lineage cells, not lymphocytes, and often includes the presence of the Philadelphia chromosome. Myelodysplastic syndromes would usually present with cytopenias more broadly rather than isolated leukocytosis.

Therefore, the combination of age, the specific type