Trisomy 13 and myeloid malignancy--characteristic blast cell morphology: a United Kingdom Cancer Cytogenetics Group survey.

We retrospectively report data on 28 patients with haematological malignancy and trisomy 13 (25 cases) or tetrasomy 13 (three cases) as the primary acquired cytogenetic change. Peripheral blood and/or bone marrow morphology was reviewed in 25/28 cases and the final diagnosis was as follows: AML M0 (11), AML M1 (6), AML M2 (2), AML M4 (2), AML M5b (1), AML M6 (1), RAEB-t (3), RAEB (1), RA (1). All three cases with tetrasomy 13 had AML M0. Characteristic small hand-mirror blasts with cytoplasmic blebs and tails and scanty small granules were seen in 13/25 cases and 18/25 cases had small blasts which could easily be mistaken for lymphoblasts. Trilineage dysplasia was present in 8/28 cases. Median patient survival was 3 months. We conclude that trisomy 13 is particularly associated with acute myeloid leukaemia with minimal differentiation (AML MO), often has distinctive morphological features, and has a poor prognosis.