Submitting Author: Raess, Philipp W., MD, PhD
Institution: University of Pennsylvania
Additional authors:James Monaco PhD, Ronak Chawla, Michelle Paessler DO, Mitchell J Weiss MD PhD, Anant Madabhushi PhD, John K Choi MD PhD, Adam Bagg MD
Session: AML with myelodysplasia-related changes

A 74-year-old man was admitted for chronic sinusitis. A complete blood count demonstrated anemia (hemoglobin = 8.6 g/dL), thrombocytopenia (platelets = 111 x 10^3/microliter), and a white blood cell count of 5.2 x 10^3/microliter with 74% neutrophils, 24% lymphocytes, 1% bands, and 1% myelocytes. A bone marrow biopsy was obtained.

The Wright-Giemsa stained aspirate smear contained hypercellular spicules with a reversed myeloid:erythroid ratio of 1:2. Erythroid precursors were left-shifted and show frequent atypia, including nuclear irregularity, multilobation, binucleation, and megaloblastic change in >10% of cells. Blasts were not increased.

The iliac crest bone marrow biopsy was fixed in B5 and decalcified. H&E stained sections showed marked hypercellularity (>95%) with a reversed myeloid:erythroid ratio of 1:2. There were scattered immature cells with large round nuclei, vesicular chromatin, and moderate amounts of cytoplasm that accounted for less than 5% of total cellularity. Megakaryocytes were markedly increased and dysplastic (>10%) with large hypolobated forms, hyperchromatic nuclei, and clustering.

Anti-alpha-hemoglobin stabilizing protein (AHSP) immunohistochemistry was performed on the bone marrow biopsy to identify immature erythroid precursors. AHSP staining demonstrated marked architectural disarray of erythroid precursors and confirmed the morphologic impression of erythroid hyperplasia. CD71 demonstrated a similar staining pattern, highlighting nucleated erythroid precursors. CD235a and Hemoglobin A stains were difficult to interpret due to staining of non-nucleated erythrocytes throughout and surrounding the core biopsy.

Flow cytometry was performed on the bone marrow aspirate and did not demonstrate an expansion of blasts.

Karyotype: 46,XY,t(1;16)(p32;q22),del(20)(q11.2)[20]

This case illustrates the utility of a novel immunohistochemical marker for erythroid cells that (1) appears superior to other currently available reagents; and (2) is of value in the evaluation of architectural disarray of erythroid precursors, a histologic feature of MDS in bone marrow biopsies.

AHSP is a chaperone molecule that binds the alpha globin chain and is expressed only in nucleated erythroid precursors. AHSP is no longer expressed in non-nucleated erythrocytes (and hence is preferred to both CD235a and Hemoglobin A), and it is specific for erythroid lineage (and thus is preferred to CD71 which may be detected in proliferating or neoplastic cells).

In this case, AHSP immunohistochemistry highlighted the architectural disarray of erythroid precursors (which was not an issue in this specific case since this was evident histologically), supporting the diagnosis of MDS. AHSP also marked immature-appearing erythroid precursors, allowing for differentiation between myeloid and erythroid blasts and thus accurate diagnosis.

We performed preliminary image analysis on this case using a computerized algorithm to differentiate bone marrow biopsies from patients with refractory cytopenia with multilineage dysplasia from normal. The algorithm first identifies adipose tissue, then traces the boundaries of all groups of contiguous pixels classified as positively stained for AHSP. The following features are then extracted: ratio of the area of cellular tissue to the total tissue area (derived from the map of adipose tissue) and the 85th percentile of the stained regions (derived from the boundaries). Each image is classified as MDS or normal based on its features values (see figures in PowerPoint).

Refractory cytopenia with multilineage dysplasia (with the use of a novel marker, AHSP, to facilitate the detection of erythropoietic disarray).

Refractory cytopenia with multilineage dysplasia

Case 242