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Pelger Huet anomaly: general

- defect of terminal neutrophil differentiation (lamin B receptor mutation)

- leading to defects in scaffolding proteins that control shape of nuclear membrane

Pelger Huet anomaly: histo

nuclear hyposegmentation of neutrophils and other granulocytic cells

Pelger Huet anomaly: clinical

- soft tissue infections

- may be clinically silent

chronic granulomatous disease: general

- mutations in components of NADPH oxidase in phagocytes

- leading to impaired destruction of phagocytosed microorganisms

chronic granulomatous disease: histo

- nitroblue tetrazolium (NBT) test to screen for NADPH oxidase defects

- neutrophils exposed to stimulus, incubated with NBT = granules are the reaction products (normal)

- CGD = no granules

chronic granulomatous disease: clinical

- severe, recurrent bacterial and fungal infections in any organ

- e.g. pneumonia, abscess, osteomyelitis, lymphadenopathy

Chediak Higashi syndrome: general

- mutation in lysosomal trafficking regulator (LYST) gene, involved in intracellular trafficking of protein

- leading to failure of microtubule formation

Chediak Higashi syndrome: histo

- neutrophils do not respond to chemotactic signals

- giant lysosomal granules fail to function

Chediak Higashi syndrome: clinical

- soft tissue abscess with Staph aureus

- platelet issues

- Schwann cell issues

- NK and T cells

typical bone marrow presentation

50% fat, 50% cells - decreases with age

megakaryocytes, myeloid, erythroid, lymphoid

trilineage hematopoiesis

- megakaryocytes

- erythroid precursor colonies

- granulocytic precursors and mature forms

erythroid maturation: stages

pronormoblast

basophilic normoblast

polychromatophilic normoblast

orthochromic normoblast

polychromatophilic RBC (reticulocyte)

mature RBC

erythroid maturation: visual effects

- cell size decreases

- cytoplasm ratio decreases

- nuclear size decreases and disappears

- cytoplasm staining changes from blue to pinkish red

- chromatin pattern matures and disappears with nucleus

granulocytic maturation: stages

myeloblast

promyelocyte

myelocyte

metamyelocyte

band neutrophil

segmented neutrophil

granulocytic maturation: visual effects

- cell size generally decreases

- nuclear volume generally decreases

- nuclear maturation goes from round, fine chromatin to segmented, dark chromatin

- N:C ratio decreases

- no cytoplasmic granules to primary/azurophilic granules to specific/secondary granules

lymphoma workup: areas of study

- surgical pathology or cytology

- flow cytometry

- cytogenetics

- Fluorescence In Situ Hybridization (FISH)

- molecular studies

the lymphoma workup evaluates the cells at various levels:

- to characterize the cells (type of lymphoma or leukemia)

- to understand genetic abnormalities

- info to guide treatment, response to therapy, prognosis

hematopoietic tissues in the body

- lymph nodes - cervical, axillary, abdominal, pelvic, groin

- spleen

immunophenotyping: definition

using markers (antigens) expressed by the cells to analyze patterns and identify the cells

2 methods = flow cytometry and immunohistochemistry

flow cytometry

- tissue goes in RPMI, a media that keeps cells alive

- fresh flowing cells

- cells will emit fluorescence that will be read and the patterns will be reported

IHC

performed on the tissue once it is made into slides

cytogenetics

- a complete overview of the entire set of chromosomes

- examine for any additional, lost, or exchanged material

- needs fresh tissue so that cells can be grown in the lab

FISH

- examining chromosomes with specific chromosomal abnormality targets

- some tumors have recurring, defining, or characteristic chromosomal abnormalities

- fresh tissue preferred, fixed acceptable

molecular studies

- can be done on fixed tissues

- Polymerase chain reaction (PCR) to measure specific genes

- DNA sequencing to determine the precise order of nucleotides

Bone aspirate allows for a closer look at…

cell morphology and cell counting

acute myeloid leukemia: general

- affects primarily adults

- responds fairly well to treatment

- prognosis somewhat worse than that of acute lymphoblastic leukemia

acute myeloid leukemia: histo

- bone marrow filled with myeloblasts

- large nucleus with immature chromatin = fine, not clumped

- prominent nucleoli

- scant/variable cytoplasm

acute promyelocytic leukemia: histo

- promyelocytes with bilobed nuclei

- more cytoplasm

- numerous Auer rods (*not always present)

acute promyelocytic leukemia

- driven by balanced (15:17) (q24.1: q21.2) (PML:RARA) reciprocal translocation

- exclusively in APL

acute promyelocytic leukemia: how

the promyelocytic leukemia (PML) gene on chromosome 15q24.1 fuses with the retinoic acid receptor alpha (RARA) gene on chromosome17q21.1 = blocks myeloid differentiation

acute promyelocytic leukemia: PML

wildtype is a tumor suppressor gene

acute promyelocytic leukemia: RARA

promotes cell differentiation and suppresses cell growth

acute promyelocytic leukemia: treatment

- all-trans retinoic acid (ATRA)

- allows re-expression of genes regulating promyelocyte differentiation

- promotes differentiation to neutrophils

- can induce a complete response in APL

acute promyelocytic leukemia: clinical

- medical emergency = life-threatening coagulopathy

- imbalance of pro and anticoagulant factors

- pro-coagulant released from leukemic cells

- treatment started based on presumptive diagnosis using morphology

B-ALL: general

- B-acute lymphoblastic leukemia (B-ALL)

- most common childhood neoplasm

- Outside the bone marrow, CNS and testis are reservoirs for leukemic cells and are common relapse/rcurrences sites

B-ALL: clinical

- fevers, night sweats, poor PO intake, fatigue, anemia, thrombocytopenia

- petechiae in skin and mucous membranes

- CBC with markedly elevated white count

B-ALL: histo

- marked elevation of "other cells" = blasts

B-ALL: favorable factors

- 1-10 years of age

- female

- WBC < 50×10^9/L

- no CNS disease

B-ALL: unfavorable factors

- <1 or >10 years

- male

- WBC > 50×10^9/L

- presence of CNS disease

germinal center: normal histo

- light (centrocytes) and dark (centroblasts) areas in the germinal center

- tingle body macrophages (cytoplasmic debris)

- CD20 highlights B-cells in the follicle

- CD3 highlights T-cells in interfollicular areas

germinal center: BCL2

- negative in normal GCs

- has antiapoptotic activity

- when B-cells are undergoing antigen-driven selection in GCs, the lack of BLC2 expression allows cells to undergo apoptosis if necessary

follicular lymphoma: general

- neoplastic proliferation of small B cells (CD20+) that form follicle-like nodules

- t(14;18) (q32;q21)/IGH::BCL2

- overexpression of BCL2 = positive BCL2 stain

follicular lymphoma: histo

- large, irregular follicle

- no polarization

- encroaching on the subcapsular sinuses

- germinal centers are comprised of large centroblasts

necrotizing lymphadenitis

granulomas, necrosis

pink grunchy material

have to rule out infectious etiologies

granulomatous lymphadenitis: histo

asteroid body

fish flesh

tan-white or gray appearance, opaque, slightly bulging from cut surface

GI lymphomas: general

- GI tract is the most common site for extranodal lymphomas

- 50-60% stomach

- 30% small bowel

- 10% large bowel

What are the most common types of lymphoma that occur in the GI tract based on site?

- stomach = DLBCL, extranodal marginal zone lymphoma

- small bowel = DLBCL

- large bowel = DLBCL

GI lymphomas: gross

- varies

- nodularity, thickening of the mucosa/wall

- plaque-like lesion

- ulcerative tumoral masses with transmural infiltration (characteristic appearance of DLBCL)

- fish-flesh cut surface

When suspecting lymphoma =

review the history

gross appearance

request a consultation

chronic lymphoid leukemia: histo

- monotonous population of lymphocytes with mature, clumped chromatin (looks like a soccer ball)

- leukocytosis

- lymph node architecture is effaced

chronic lymphoid leukemia: immunophenotype

- CD20+ = B-cell marker

- CD23+ = subset of activated mature B cells, activated monocytes/macrophages, T cell subsets, platelets, eosinophils, Langerhans cells, follicular dendritic cells

- CD5+ = aberrant, T-cell marker expressed on a subset of transitional B-cells

pseudofollicles

- pale areas of LNs that resemble follicles at first glance

- proliferation centers containing a spectrum of mature B cells with larger, activated forms (prolymphocytes and paraimmunoblasts)

- dark surrounding areas are small, mature Bcells

mantle cell lymphoma: general

- neoplastic proliferation of small B cells (CD20+) that expand the mantle zone in lymph node follicles

- involves lymph nodes, bone marrow, liver, GI (lymphomatous polyposis)

mantle cell lymphoma: histo

- positive for CD5 but negative for CD23

- can be nodular and surround pre-existing germinal centers

mantle cell lymphoma: cytogenetics

- t(11;14)::CCND1:IgH

- CCND1 (CyclinD1) = facilitates cell cycle progression from G1 to S phase, also an immunostain used frequently when evaluating these lesions

Richter transformation

- aggressive B-cell lymphoma arising from a patient's CLL/SLL

- common type = diffuse large B-cell lymphoma (DLBCL_

- uncommon = classic Hodgkin lymphoma

- rare = plasmablastic lymphoma, B-lymphoblastic lymphoma

- must be clonally related to CLL/SLL, it is myeloid and likely de novo

chronic myeloid leukemia: accelerated phase

- increased myeloblasts in blood/bone marrow or >20% basophils in blood

chronic myeloid leukemia: blast phase

>20% myeloblasts or >5% lymphoblasts

leukoerythroblastosis

- poikilocytosis - varying shape of RBCs, teardrops

- myeloid precursors

- erythroid precursors

myelophthisis

- the process of bone marrow infiltration resulting in extramedullary hematopoiesis

- fibrosis and metastatic cancer

myelofibrosis: general

replacement of bone marrow by fibrous tissue

aspirate cannot yield cells bevause it would be a dry tap due to the fibrosis

myelofibrosis: histo

- reticulin stain for increased collagen fibers

- streaming of cells

- atypical megakaryocytes

Myeloproliferative Neoplasms

- bone marrow hypercellularity

- intact maturation with effective hematopoieses

- elevations of >/ HP lineages in blood

- splenomegaly = a hallmark

- mutations in tyrosine kinase

myelodysplatic syndrome

- dysplasia of megakaryocyte and erythroid lineages

- megakaryocyte nuclei are hypolobated

- erythroid line shows fraying and irregularity of chromatin and binucleation

- loss of synchrony between cytoplasmic and nuclear maturation

- ringed sideoblasts = iron surround erythroid nucleus

multiple myeloma

- aka plasmacytoma

- plasma cells comprising >30% of bone and forming a mass lesion

hodgkin lymphoma: histo

- Hodgkin Reed-Sternberg cell

- lacunar cells = retraction artifact of Hodgkin cells in formalin-fixed tissues

MALT lymphoma: general

- mucosa-associated lymphoid tissue lymphoma

- most common extranodal marginal zone lymphoma

- mature B-cell lymphoma

- arises at sites of chronic inflammation

- induced by chronic H pylori gastritis in the stomach

- eradication of H pylori results in disease remission with low rates of recurrance

MALT lymphoma: histo

- dark blue cells overrunning the mucosa

- some glands gone

- lymphoma cells infiltrate the glands to form lymphoepithelial lesions

Burkitt lymphoma: general

- highly aggressive B-cell neoplasm

- germinal center B-cell immunophenotype with MYC overexpression (MYC translocation partnered with Ig gene loci (IgH heavy or light chain)

- EBV infection in a subset of cases

Burkitt lymphoma: variants

- endemic

- spradic

- immunodeficiency-associated

Burkitt lymphoma: histo

- diffuse growth pattern with starry-sky pattern (stars = numerous macrophages with phagocytized debris)

- high mitotic rate

- necrosis

- appendix diffusely involved by an infiltrate of dark blue cells = hard to distinguish layers

EBV: infected B cells

induce cell-mediated response in CD8+ T cells

EBV-associated lymphomas

- Burkitt lymphoma

- Classic Hodgkin lymphoma

- EBV+ DLBCL

- post-transplant lymphoproliferative disorder

- plasmablastic lymphoma

- DLBCL associated with chronic inflammation

- fibrin-associated DLBCL

- EBV+ mucocutaneous ulcer

- primary CNS lymphoma

EBV-associated carcinomas

- EBV-associated gastric carcinoma

- nasopharyngeal carcinoma

- inflammatory pseudotumor-like follicular dendritic cell sarcoma

- lymphoepithelioma-like salivary gland carcinoma

malabsorption pattern: histo

- villous atrophy/blunting

- crypt hyperplasia

- intraepithelial lymphocytes

- increased chronic inflammation in the lamina propria

malabsorption pattern: diff dx

- celiac disease

- hypersenstivity to non-gluten proteins

- small intestineal bacterial overgrowth

- malnutriotion

- medications

- immune dysregulation disorders

celiac disease

- correlates with tissue transglutaminase and antiendomysial antibodies

- HLA-DQ2 and HLA-D8 genotypes

celiac disease: clinical symptoms and complications

- weight loss, weakness, diarrhea

- iron deficiency anemia

- growth restriction and failure to thrive (in children)

- T-cell lymphoma

- small bowel adenocarcinoma

3 major categories of anemia

- blood loss

- hemolysis

- decreased/impaired RBC production

anemia: blood loss

- acute - trauma

- chronic - GI and gyn tracts

microcytic anemia: hemolysis

- hereditary spherocytosis

- G6PD deficiency

- hemoglobinopathies

- thalassemia

- Ab-mediated

- RBC trauma

- microangiopathic hemolytic anemia

- infection e.g. malaria

macrocytic anemia: impaired RBC production

- disturbed proliferation of tem cells or erythroblasts

- defective DNA synthesis

- iron deficiency

- anemia of chronic inflammation

- anemia of renal failure

- marrow replacement or infilitration

What do RBCs need to be successful?

- deformability

- stable hemoglobin and oxygen carrying capacity

- self-sufficiency

Monospot Heterophile Antibody Test

Positive serum = clumping, heterogenous solution

Negative serum = no clumping, homogenous solution

Chronic Myeloid Leukemia (CML)

marked nontoxic neutrophilia, left shift to blasts, and basophilia; thrombocytosis

BCR:ABL / 9:22 (Philadelphia chromosomes)

Polycythemia vera (PV)

erthyrocytosis

Jak2

Primary myelofibrosis (PMF)

leukocytosis, leukoerythroblastic picture, tear-shaped RBCs

Jak2

Essential thrombocythemia (ET)

thrombocytosis

Jak2

Chronic neutrophilic leukemia (CNL)

marked mature neutrophilis with toxic changes and minimal left shift

CSF3R

Chronic eosinophilic leukemia (CEL)

marked eosinophilia

PDGFR, exclude other mutations