Discrepancy In Diagnosis of Myelodysplastic Syndrome (MDS) Between Referral and Tertiary Care Centers: Experience at MD Anderson Cancer Center (MDACC)

Patients (pts) referred to tertiary care centers occasionally have a final diagnosis that may differ from that made at the initial referring center. Previous studies have shown a discordance of 18% in the diagnoses of leukemia patients (AMJ. 1998;104:246-251). The aim of this study was to analyze the rate and implications of diagnostic discordance in pts with MDS referred to MDACC.

A total of 915 pts presented to MDACC between September 2005 and December 2009 with an outside diagnoses of MDS. We reviewed the medical record of each patient for the pathology report on the diagnostic outside bone marrow slide sent for review. We also reviewed the outside hematopathology report sent with it. Diagnoses were coded according to WHO and the FAB MDS classification systems depending on time period. Information on pt characteristics including age, gender, IPSS, cytogenetics, complete blood count, % bone marrow blasts and transformation to acute myeloid leukemia (AML) were also recorded. Finally median survival was calculated using Kaplan-Meier method.

Out of the 915 charts reviewed, discordance in diagnosis was documented in 150 pts (16%). Sixty pts (40%) had an outside diagnoses of RA/RARS/RCMD/RCMD-RS (marrow blast <5%). Forty-six (77%) of these were diagnosed with RAEB (marrow blasts 5 to 20%) and 6 (10%) with RAEB-T (marrow blasts >20%) at MDACC. Similarly, 15 (26%) pts diagnosed with RAEB on the outside, were diagnosed with RA/RARS/RCMD/RCMD-RS at MDACC whereas 40 (70%) pts diagnosed with RAEB were diagnosed with RAEB-T. Only 2 pts diagnosed with RAEB-T on the outside were diagnosed with RAEB at MDACC. Moreover, 3 pts were diagnosed with chronic myelomonocytic leukemia (CMML), 3 with MDS unclassified, 2 with MDS/MPD had a different diagnoses at MDACC. The characteristics of pts with discordance were compared with the 765 pts without discordance. Essentially no difference was noted in the age, gender, cytogenetics, hemoglobin or platelet count between the two groups. A difference was noted with pts in the discordant group having a higher percent of RAEB-T (37% vs. 10%, p<0.0001). Similarly the discordant group was noted to have a greater number of high risk IPSS pts; 30% vs. 13% (p< 0.0001) and greater than 20% marrow blasts (25% vs. 8%, p<0.0001). No difference was noted in transformation to AML between the 2 groups: 13% vs. 8% (p=0.11). Seventy-eight (52%) pts in the discordant group and 372 (49%) pts in the non-discordant group died. Despite the differences noted above, no difference was observed in the median survival between the 2 groups by the Kaplan-Meier method (p=0.39). The median survival of both the groups was 15 months. Also only 19 pts in the discordant group were noted to have an outside report/marrow slide of > 6 months. Nine pts of these showed a higher marrow blast percentage than outside, indicating progression of disease.

Discordance in the diagnosis of MDS pts is important as it can affect the treatment plan and overall prognosis of these patients. In our study, pts in the discordant group were observed to have a higher risk disease. However, no significant difference in survival was noted between the two groups. These results demonstrate the complexity of the morphological diagnosis of MDS and indicate that morphological classifications have a limited role in the prognosis of these pts. Analysis of implications of therapy based on diagnostic discordance is ongoing.

No relevant conflicts of interest to declare.