Alpha-Hemoglobin Stabilizing Protein Specifically Identifies Nucleated Erythroid Precursors and Enables Identification of Architectural Distortion in Myelodysplastic Syndromes by Computerized Image Analysis
Philipp W Raess, James Monaco, Ronak Chawla, Michelle Paessler, Adam Bagg, Mitchell J Weiss, Anant Madabhushi, John K Choi. U. of Pennsylvania, Philadelphia; Rutgers U., Piscataway, NJ; Children's Hospital of Philadelphia, Philadelphia; St Jude Children's Research Hospital, Memphis
Background: Alpha-hemoglobin-stabilizing-protein (AHSP) is an abundant erythroid-specific chaperone protein that facilitates incorporation of nascent alpha-globin into hemoglobin A. Architectural disarray of erythroid islands is sometimes evident in myelodysplastic syndromes (MDS) but is subjective, limiting its use as a diagnostic criterion.
Design: We characterized AHSP expression by immunohistochemistry in a panel of 85 neoplastic and reactive bone marrow biopsies (BMBx) and compared it to established erythroid markers CD71 and CD235a. We then used AHSP to determine if erythroid architectural disruption could distinguish normal cases from those with MDS. We developed a computerized image analysis algorithm to identify AHSP-expressing cells, extracted morphologic features (BMBx cellularity, size of erythroid clusters) of the biopsies to assess erythroid disarray, and classified images as 'MDS' or 'Normal'.
Results: AHSP expression was limited to physiologic nucleated EPs in all control cases and blasts in erythroleukemia and pure erythroid leukemia. While CD71 also stained EPs in all of these samples, it additionally decorated non-erythroid blasts in many other cases of acute leukemia, diffuse large B cell lymphoma cells, and metastatic small cell carcinoma. Although CD71 staining of these cells was less intense than the staining seen in EPs, it was clearly above background. CD235a stained both EPs and non-nucleated RBCs in all specimens, limiting its utility.
Computerized image analysis identified cellularity and the size of AHSP-expressing erythroid clusters to be the features that best discriminate cases of MDS from normal. Receiver operating characteristic curves generated for these features demonstrate areas under the curve of 0.8875 for cellularity, 0.8661 for the size of erythroid clusters, and 0.9366 for the combination of these two features.
Conclusions: AHSP is superior to CD71 and CD235a for detecting normal and neoplastic nucleated erythroid precursors. Computerized image analysis of AHSP-stained BMBx is an objective assessment of erythroid architectural disarray and marrow cellularity and may be a valuable tool to facilitate the diagnosis of MDS.
Monday, March 19, 2012 9:30 AM
Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 235, Monday Morning