Oral leukemic infiltration is the presence of localized or generalized tissue hyperplasia of the mouth caused by collections of malignant white blood cells or their precursors. The demographic features follow that of the particular leukemia. However, the most common presentation is leukemic infiltration of the gingiva in acute monocytic or acute myelomonocytic leukemia, a disease of adults. Lesions are generally not painful, although they may bleed. Because of immunosuppression secondary to the leukemia, lesions may also exhibit secondary infection by viral or fungal agents.

Patients report weight loss, fatigue, loss of appetite, and easy bruisability. The infiltrate often develops over weeks and months.