Perl's Stain Grade in the Bone Marrow Aspirate Correlates with Overall Survival in Low Risk Myelodysplastic Patients
Authors: Pilo Federica , Caocci Giovanni , DiTucci Anna Angela , Serreli Valentina , Angelucci Emanuele , La Nasa Giorgio 
Published: October 2019

Abstract
Background
Myelodysplastic syndromes (MDS) are heterogeneous group of acquired clonal hematopoietic stem cell disorders characterized by atypical stem cells maturation and genetic instability leading to an enhanced risk of progression to acute myeloid leukemia. Low risk MDS patients have a lower probability to evolve in leukemia but are commonly characterized by dyseritropoiesis. These patient are incline to long term accumulation of iron in the organs due mostly to red blood cell transfusion (RBC) but iron overload may also occur in MDS patients who do not receive RBC transfusions due to the ineffective erythropoiesis. It is well known the effect of oxidant-mediated tissue's injury through the formation of free toxic iron species in the liver and heart site, but recent knowledges assumes that this mechanism is effective also in the bone marrow nice, where oxidative stress seems to impaired the haematopoietic stem cells growth. At this moment microscopic examination of the stainable iron in the bone marrow is considered the gold standard for determining the iron stores. The effect of bone marrow's iron overload on overall survival in the low risk MDS has been a matter of unresolved debate. We aimed to investigate the predictive value of bone marrow iron accumulation as demonstrated by Perl's staining on outcome in such patients.
Design
We retrospectively analyzed all low risk,intermediate-I MDS patients who had diagnosed in our institution in the last 20 years (since 1998). Diagnosis of MDS was made according to WHO criteria. Patients were stratified based on International Prognostic Scoring System (IPSS). Patients had undergone bone marrow aspiration as part of the diagnostic work up for their MDS. Two different experienced hematologist analyzed all samples. Bone marrow aspiration slides with at least seven fragments were considered suitable. Perl's Prussian blue stain was used to stain bone marrow, assessed by modified Gale's grading (Tab. 1) and then correlated with outcome.
Patients and methods
Marrow staining of one hundred and fourteen consecutive MDS patients were revised and analyzed. Median age was 70 years (range 32-93). Eighty three patients were IPSS low- risk and 30 Intermediate I. All patients were evaluated for bone marrow iron stores with Perl's stain. Twenty-seven patients had grade 1 (+), 31 grade 2 (++) and 56 grade 3 (+++). Patients had never or minimally received RBC . None of these patient had received iron chelation before marrow examination. Probability of overall survival (OS) was estimated by the Kaplan-Meier method and the significance was assessed by the log-rank test.
Results
20-year OS was significantly lower in patients with higher Perl's score (median = 80 ±7 months in grade 3; median = 70 ±17 months in grade 2; median = 144 ±18 months in grade 1 , P=0.011); Fig. 1
Conclusions
We evaluated retrospectively the bone marrow aspirate from 114 consecutive new MDS low-risk, Intermediate-I IPSS patients with Perl's stain for iron detection. Although Perl's grading is a qualitative method, it is still the gold standard to detect iron storage in the bone marrow. Our results correlate Perl's stain at diagnosis with long term outcome in MDS patients. We show how higher grade of iron storage at diagnosis can impact on outcome in these patients. We conclude that Perl's stain, together with Ferritin and blood transfusional burden could be another marker at diagnosis of iron-related toxicity that predict overall survival.

Disclosures
Pilo: Novartis Italy: Honoraria. Angelucci:Jazz Pharmaceuticals Italy: Other: Local ( national) advisory board; Vertex Pharmaceuticals Incorporated (MA) and CRISPR CAS9 Therapeutics AG (CH): Other: Chair DMC; Roche Italy: Other: Local (national) advisory board; Novartis: Honoraria, Other: Chair Steering Comiittee TELESTO Protocol; Celgene: Honoraria, Other: Chair DMC.