A. ROVÓ ET AL. ERYTHROGRAM PATTERN OF SIDEROBLASTIC CHANGES 331 of the erythrogram to predict sideroblastic changes in the bone marrow. D E S I G N A N D M E T H O D S This was a single center study with a two step model design. In the ﬁrst step, we reviewed all reports of bone marrow cytology performed in the Hematology Laboratory of the University Hospital of Basel between January 2004 and June 2006. Any case with 15% RS in the iron staining (MDS, other myeloid neoplasms, or reactive forms of sideroblastic anemia) and having a peripheral blood count performed with an ADVIA 120 system, were included in the study. These cases were compared with a control group of 30 patients with a myeloid neoplasm presenting dysplastic features without RS. We deﬁned as RS-pattern (Figure 1bii) an erythro- gram with a broad distribution of the RBCs over nearly eight of the nine areas of the scattergram (Figure 1a), with dots spread over the macrocytic, microcytic and hypochromic areas. All other erythrogram patterns were considered as non-RS-pattern. The erythrogram as well as numerical RBC parameters were compared between both groups. The second step of the study aimed to validate the RS-pattern. Therefore, from January 2006 to June 2008, we collected prospectively all cases with a RS- pattern performed in the Hematology Laboratory and evaluated their predictive value for sideroblastic changes in the iron staining of bone marrow cytology. The Hematology Laboratory operates as a central Lab for the whole University Hospital, performing a mean of 600 automated peripheral blood counts daily. For this second step, the technicians were trained to iden- tify the RS-pattern during their routine work. From each newly detected peripheral blood count with a RS-pattern, a smear of peripheral blood was per- formed and together with the erythrogram forwarded to the physician in charge of the laboratory to initial- ize the required investigations. All patients with repre- sentative cytology smears of the bone marrow were included for this analysis in the validation group. Patients with repetitive evaluations were considered only once. This study has the approval of our Institu- tional Review Board. A Mann–Whitney U-test was used to show numer- ical differences between groups. In all statistical procedures, P < 0.05 was considered the level of sig- niﬁcance. Statistical analysis was performed using SPSS statistical software (SPSS for Windows, Release 14.0; SPSS, Inc., Chicago, IL, USA). R E S U L T S A N D D I S C U S S I O N In the ﬁrst step of the study, 38 cases with newfound RS in the bone marrow and available ADVIA periph- eral blood analysis were identiﬁed within 3285 evalu- ated bone marrow results. Thirty two (84%) of the 38 cases had the typical RS-pattern in the erythro- gram. In the control group none of the 30 patients without RS (P < 0.0001) had such a pattern. This typical RS-pattern has a numerical background (Table 1). There were signiﬁcant differences in RBC- indices between patients with and those without RS. Only few RS-patients showed microcytic (6/38), or hypochromic anemia (7/38) or had a decreased con- tent of hemoglobin of the reticulocytes (CHr) (2/38). These ﬁndings contrast with the high number of RS- patients with an increased percentage of hypochromic RBC (hypoRBC). RS-patients showed consistently 3% hypoRBC (26/38, 68%) compared to patients without RS (7/30; 23%). The combination of increased hypoRBC and low CHr is usually closely related to iron deﬁciency (Fishbane et al., 1997, 2001; Tessitore et al., 2001; Kotisaari et al., 2002; Radtke et al., 2005). In our cohort with RS, we have the par- ticular constellation of increased hypoRBC, but nor- mal CHr (25/26 RS-patients). An increased percentage of hypochromic erythrocyte has been pre- viously described in patients with refractory anemia and RS (Ljung, Back & Hellstrom-Lindberg, 2004; Murphy et al., 2006). Another constant feature in patients with RS-pattern was the increased red cell distribution width (RDW) with values 19% in 22/ 38 (58%). In contrast, a RDW 19% was observed only in 3/30 (10%) patients without RS. Despite sig- niﬁcant differences found between patients with and without RS, none of these numerical parameters used without the erythrogram was useful in the daily practice to predict sideroblastic changes in the bone marrow. Indeed, ﬁrst, for each individual parameter, there was a substantial overlap between patients with and without RS. Secondly, we looked for a useful tool in the daily practice allowing to suspect the pres- ence of RS at ﬁrst sight. None of the numerical parameters fulﬁlled these criteria. 2009 The Authors Journal compilation 2009 Blackwell Publishing Ltd, Int. Jnl. Lab. Hem. 2010, 32, 329–335