Leukemia Cutis Exhibiting the Koebner Phenomenon: A Rare Clinical Presentation of Acute Myeloid Leukemia.

Leukemia cutis with predilection for sites of prior cutaneous trauma, often described as a Koebner-like phenomenon, is a rare but recognized occurrence. We present a unique case of an, otherwise, healthy male who developed leukemia cutis at a prior unrelated biopsy site, leading to a new diagnosis of acute myeloid leukemia (AML). Certain AML subtypes with extramedullary propensity, particularly M4 and M5, as seen in our patient, are associated with an increased risk of leukemia cutis. Unlike their medullary counterparts, extramedullary AML cells preferentially migrate to and persist in tissues outside the bone marrow, where the local microenvironment may promote immune escape. Although the localization of leukemia cutis to the biopsy site is consistent with a Koebner-like response, it remains uncertain whether subclinical leukemic cells were already present at the time of the initial excision; therefore, a definitive causal relationship between trauma and leukemic infiltration cannot be established. Additionally, the prior keratoacanthoma and its excision may have created a localized immunocompromised cutaneous district, or