The purpose of this report is to record a patient with myelodysplastic syndrome (MDS) associated acute myelogenous leukemia (AML) and leukemia cutis who had blast expression of the neural cell adhesion molecule (NCAM) and to review the world literature on prognostic implications of extramedullary myeloid cell tumors (granulocytic sarcoma, myeloblastoma, chloroma and leukemia cutis) in MDS and MDS associated AML. Case report and world literature from January 1965-January 1994 for all cases of MDS-associated extramedullary myeloid cell tumors (EMT) is reviewed, and the first patient with EMT, MDS associated AML and blast expression of NCAM is described. There have been 46 cases of MDS associated EMT previously reported. 32 cases occurred in the absence of AML. AML developed in 47% of these patients at a mean of 38 weeks from initial EMT. Of the patients not developing AML, median survival from initial EMT was 11 weeks. Nine patients received chemotherapy at the time of EMT and had a median survival of 36 weeks. The median survival for patients receiving conservative therapy for EMT was 48 weeks. Patients (n = 15) with EMT and MDS associated AML had a poor outcome regardless of therapy with a median survival of 11 weeks. Unlike other forms of isolated EMT, MDS associated EMT is not always a forerunner of AML. Premature induction therapy for MDS associated EMT does not appear to prolong survival. EMT in the setting of MDS associated AML is associated with a poor prognosis despite aggressive chemotherapy. Blast expression of NCAM may prove to be a risk factor for EMT in MDS associated AML.