Bone Marrow Biopsy in Myelodysplastic Syndromes & Myeloproliferative Neoplasms. A Review for Anatomic Pathologists.

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1 Bone Marrow Biopsy in Myelodysplastic Syndromes & Myeloproliferative Neoplasms A Review for Anatomic Pathologists Bakul I. Dalal MD FRCPC DABP FACP FASCP Clinical Professor, Department of Pathology, UBC Hematopathologist, Vancouver General Hospital Bakul.dalal@vch.ca ( me for PDF of this presentation. Also available online) Objectives This session focuses on BMBx histopathology H&E, IHC and special stains. The blood and bone marrow aspirate findings will not be covered. At the end of this session You will know the general issues related to BMBx: indications, procedure, processing, examination, writing interpretive reports. You will have basic concept of most recent WHO classification of MPN, MDS and other chronic myeloid neoplasms. The learners will know the common and uncommon morphologic features of MPN and MDS in BMBx. 2 Indications of BMBx in Patient Suspected of Having MPN/MDS Persistent cytopenia with dysplastic features Blastemia Persistent increase in counts Leukocytosis with left shift with occasional blast, eosinophilia, basophilia, myelocyte bulge Thrombocytosis (>450x10 9 /L), with megathrombocytes Persistent erythrocytosis, with features of iron deficiency 3 1

2 How to Perform a BMBx Always have concurrent blood specimen, CBC printout, bone marrow aspirate and Bx Site: Posterior Iliac spine Occasionally anterior iliac spine, tibia etc Video of the procedure available (NEJM) (UofT) Keep the BM procedure control with you to maintain the quality Lee et al, IJLH 2008; 4 Processing of Bone Marrow Specimens Aspirate (Romanowski stains): Push film (spread). Make 6 films. At bedside. Un anticoagulated. Stain 3 films. 100 cell differential in each slide. Fix rest. Squash. Stain 1 2 Touch imprints of biopsy. Stain 2 Buffy coat preparations. As necessary. Unstained: Archive for FISH studies, extracting DNA etc. Bx/clot etc (H&E): BMBx: Cut three levels. One of them 1u thick. Paraffin or plastic (methacrylate). Fixative: Formalin better. B5 denatures nucleic acids. FISH does not work. Clot (filter) preparations: Better for IHC Lee et al, IJLH 2008 (ICSH); 5 How to Examine a BMBx Always review CBC, blood film and asp concurrently Not possible in some centers. Only biopsy available! Headings: Quality Cellularity ME ratio Erythropoiesis (incl iron stain) Granulopoiesis (incl blasts) Megakaryocytes Lymphoplasmacytic complement Stromal elements Other infiltrates Cortical and trabecular bone 6 2

3 Quality Length: 1.5 or 2 cms. Fragmentation, crushing, hemorrhage Number of hematopoietic spaces On a scale of 0 4 0: no inter trabecular spaces 1: inter trabecular spaces, but very little hematopoietic tissue 2: <10 inter trabecular spaces/w hem tissue 3: Adquate. >10 spaces/w hem. tissue. 1 2 cm long. 4: Excellent. As above, no fragmentation, no hemorrhage, longer than minimum req. Thiele et al, Hematologica Cellularity Hypo, normo or hyper for the age Ignore subcortical empty spaces (upto 5) and crushed areas Calculate hematopoietic vs all other space (fat, fibrosis, vascularity etc) Age Upper limit <2 yrs 80% 2 4 yrs 70% 5 30 yrs 60% 70% yrs 40% 50% 70 30% 40% Thiele et al, Hematologica 2005; Friebert et al, J Ped Hem Onc Stromal Complement Reticulin and collagen network: Grade away from edges, blood vessels and trabeculae Grading: 0 3, WHO 2008 MF 0: Normal. Scattered linear reticulin with no intersections (cross overs) MF 1: Loose network of reticulin with intersections MF 2: Diffuse and dense increase in reticulin with extensive intersections; collagen and/or osteosclerosis absent or focal MF 3: Coarse bundles of collagen, often with significant osteosclerosis Vascularity: CD34 IHC Thiele et al, Haematologica

4 Cortical and Trabecular Bone Osteopenia and osteosclerosis Osteoclastic and osteoblastic activity Bone remodelling and post traumatic repair 10 Reporting a BMBx BMBxand aspirate are the same tissue, so issue ONE report covering both. Several guidelines available Vancouver General Hospital format: Specimens / tests requested Clinical summary / diagnosis / indication for BMBx Lab findings, including CBC Gross description of aspirate and bx (length, fragmentation, color) Nucleated differential count: No diff / 300 / 500, Microscopy: Quality, cellularity, M:E ratio, E/G/M/LP, iron stores, stroma/microenvironment, infiltrates, trabecular bone, special tests (flow, IHC, silver etc) Lee et al, IJLH 2008 (ICSH); 11 WHO Classification of MPNs/MDS etc.. MPN or MPD? Detailed dx criteria available Vardiman et al, Blood

5 WHO Classification of MPNs/MDS etc.. 2 STI responsive Vardiman et al, Blood WHO Classification of MPNs/MDS etc.. 3 Bridge and provisional entities Vardiman et al, Blood WHO Classification of MPNs/MDS etc.. 4 Vardiman et al, Blood

6 Usefulness of BMBx in MPN / MDS Precise quantitation of cellularity Precise quantitation of blasts (no hemodilution, clotting etc) Blast % by BMAsp vs flow vs BMBx CD34 does not correlate! MDS patients Asp vs BMBx: discrepancy 65/243 cases (27%) Asp over estimating 22%, under estimating 5% BMBxvs flow: discrepancy 29/89 cases (33%) Flow over estimating 10%, under estimating 23% Asp vs flow: discrepancy 39% Prognostic value flow best prognostic factor for non RAEB Morphologic findings in BMBx in MPN and MDS Levi et al, ASH BMBx in CML Dx: Ph1 pos, BCR/ABL pos (can be done on blood before the BM procedure is done) BMBx: Hypercellular M: E ratio markedly increased Granulocyte hyperplasia, left shift, myelocyte bulge, eosinophilia, basophilia Megakaryocytes: increased, smaller (dwarf) Paratrabecular granulocyte cuff >4 cells thick Fibrosis 1 2/3 AP: Blasts increased (CD34), increasing fibrosis, increasing and crowding of abnormal megakaryocytes. BP: Blasts markedly increased, fibrosis disappears. 17 PV Vardiman et al, Blood

7 BMBx in PV Pre polycythemic and polycythemic (Cellular phase): Hypercellular marrow, panmyelosis, reticulin normal, megakaryocytes increased, pleomorphic (normal + ET like) Post polycythemic (spent) phase: Looks like fibrotic phase of PMF or ET. Hypocellular marrow, grade 3/3 fibrosis (rarely osteosclerosis), clusters of hyperchromatic megakaryocytes, intra sinusoidal hematopoiesis. 19 ET 20 BMBx in ET BMBxone of 4 major criteria. Normo or hypercellular Megakaryocyte hyperplasia Enlarged hyperlobulated megakaryocytes, staghorn, bunch of grapes Granulopoiesis, erythropoiesis not hyperplastic Fibrosis 21 7

8 PMF 22 BMBx in PMF BMBx morphology one of three major criteria. Cellular/prefibrotic phase: Hypercellular marrow Megakaryocytes markedly increased and abnormal, pleomorphic large and small, prominent crowding, endosteal / perisinusoidal; bulbous or cloud like (plump lobulation) nuclei. Fibrosis 1 2/3. Fibrotic phase: Hypocellular marrow Fibrosis 3/3, osteosclerosis Very abnormal megakaryocytes similar to cellular phase. Thiele, Sem Hematol 2005; Vardiman, Blood Megakaryocyte Morphology in MPNs CML PMF ET PV Number N > N > Localization Scattered or clustered Scatter ed clustered, paratrabecular, perisinusoidal Scattered or occ clustered Size N > (dwarf) N > N Nucleus Hypolobated bizzare, hyperchromatic, cloud-like, baloon shaped, bare nuclei Cytoplasm Scant/moderat e hyperlobulated, stag-horn, bunch of grapes moderate abundant moder ate N 8

9 BMBx Morphology in MPNs Does Not Always Correlate with Clinical/Lab findings 29 patients with MPN and thrombosis Detailed BMBx morphology WHO classification: N=29; ET 6, PV 11, PMF 11, NOS 1 Correlation with clinical / lab criteria: ET 2/6, PV 3/11, PMF 11/11 Remainder called NOS Gianelli et al, Leuk Res 2015 BMBx Morph in JAK2-mut vs JAK2-wt MPNs (ET & PV) Campbell et al, Lancet BMBx IHC for Molecular Abnormalities: CALR JAK2 and MPL donot work by IHC. Calreticulin is endoplasmic reticulum based Ca binding protein. CALR gene is mutated in 50 80% of patients with JAK2 neg, MPL neg ET or PMF patients. Expected to be included in the WHO 2015/6. Together, JAK2, MPL and CALR molecular markers account for 80 90% of ET/PMF group % are triple negative. Antibodies to mutated CALR are commercially available. Mark megakaryocytes. Tefferi et al, Leuk

10 BMBx in Mastocytosis BMAsp: Abnormal shaped mast cells BMBx: Pseudogranulomatous lesions IHC 28 Myelodysplastic Syndromes Diagnosis and classification of MDS is based mainly on blood and bone marrow aspirate findings: % of blasts Dysplastic morphology Extent of dysplasia: uni or multi lineage Other findings 29 BMBx in MDS BMBx has a limited role: ALIP is powerful prognostic marker Classification Staging: Precise blast quantitation tissue distribution of blasts Hypocellular MDS from SAA 5q : Megakaryocyte morphology RARS / RARS T: Iron stores, ringed sideroblasts MDS F: MDS/w fibrosis FISH possible (In C/O dry tap), except in B5 fixed tissue

11 ALIP Abnormal localization of immature precursors GCSF secreted by stromal cells in para trabecular location Three aggregates in each level of >5 immature cells, >100u from the bony trabecula Can be seen in regenerative marrow. Should differentiate from aggregates of megaloblastic erythroid precursors, and from monocyte aggregates. 31 Association of ALIP with OS Verburgh et al, JCO Iron Perl s reaction 11

12 CD34 IHC in MDS CD34 pos in 80 90% of blasts in MDS. 1/3 the expression is partial, so quantitation inaccurate CD117 second choice; however, also positive in promyelocytes Precise staging RA vs RAEB1 vs RAEB2 Discrepancy. BMAsp diff still rules Blast aggregates indicate aggressive course Hypocellular MDS vs Aplastic Anemia H&E morph helps in 10 20% of cases. Cytogenetics helps in 25%. CD34pos cells (IHC) in 10 HP fields 10 in hypocellular MDS (0 45) vs 3 in SAA (0 8). p53pos cells 3 (0 36) vs 0 (0 7). Orazi et al, AJCP 1997; Cha et al, AnnLabMed CD34 IHC in MDS 2 CD34+ megakaryocytes, >20%. Seen in 29/202 (15%). More blasts, cytopenia, bad cytogenetics, short survival Tang et al, Leuk Res MDS-F N=79 (13%) Shorter LFS, OS 25% were JAK2 mutated. If developed during the course of disease, indicative of leukemic transformation Fu et al, Mod Pathol

13 Approach to a BMBx in MDS H&E CD34, CD117, p53 Reticulin, trichrome Perl s reaction for iron stores 37 Summary: BMBx morphology is an integral part of diagnostic algorithm of MPN and MDS. BMBx should be performed on every case of suspected MPN or MDS