A 78-year-old man shows signs of abnormal blood film and anemia. What is the most likely underlying cause?

In a 78-year-old man presenting with abnormal blood film and anemia, myelodysplasia stands out as a likely underlying cause. Myelodysplastic syndromes (MDS) are a group of disorders caused by ineffective hematopoiesis, leading to the production of dysfunctional, often misshapen blood cells. These can present with various abnormalities in a blood film, such as dysplastic changes in red blood cells, white blood cells, and platelets, which aligns with the observation of an abnormal blood film.

In older patients, MDS is more common due to genetic mutations and the cumulative effect of environmental exposures that occur over a lifetime. The anemia related to MDS can be due to ineffective erythropoiesis, which means that while the bone marrow may be producing red blood cells, they are often poorly formed and ineffective at transporting oxygen.

Other conditions such as aplastic anemia would typically present with a more marked reduction in all blood cell lines without the typical dysplastic features seen in myelodysplasia, while bone marrow metastases would often present with more advanced underlying malignancies and potentially different blood film findings, such as leukemic or infiltrative changes. Hypothyroidism, while it can cause anemia, usually would not lead to