Myeloid Sarcoma - Frequency and Patterns of Presentation - in Acute Leukemia

In Acute Leukemia

Chloromas are rare; exact estimates of their prevalence are lacking, but they are uncommonly seen even by physicians specializing in the treatment of leukemia. Chloromas may be somewhat more common in patients with the following disease features:

• French-American-British (FAB) classification class M2
• those with specific cytogenetic abnormalities (e.g. t(8;21) or inv(16))
• those whose myeloblasts express T-cell surface markers, CD13, or CD14
• those with high peripheral white blood cell counts

However, even in patients with the above risk factors, chloroma remains an uncommon complication of acute myeloid leukemia.

Rarely, a chloroma can develop as the sole manifestation of relapse after apparently successful treatment of acute myeloid leukemia. In keeping with the general behavior of chloromas, such an event must be regarded as an early herald of a systemic relapse, rather than as a localized process. In one review of 24 patients who developed isolated chloromas after treatment for acute myeloid leukemia, the mean interval until bone marrow relapse was 7 months (range, 1 to 19 months).