Lecture #10: White Blood Cell Disorders

The leukocyte disorders can be grouped into:

A. Non–neoplastic disorders – non–tumor related disorders (Lecture #9)

B. Neoplastic and related disorders – tumor related disorders

1.     Leukemias and Leukemoid Reactions

a. Leukemia is a generalized neoplastic proliferation or accumulation of leukopoietic cells with or without involvement of the peripheral blood. Leukocytosis, abnormal circulating cells and infiltration of non–hematopoietic tissues are frequently but not invariably present

Classification of Leukemias

(1)   Chronologic (based on natural history)

(a)   Acute – rapidly progressing, lasting for several days to six months

(b)   Sub–acute – lasting from two to six months or even 12 months

(c)    Chronic – length of the disease is variable depending on the age of the patient and type of cells involved. Host patients will live a minimum of 1 to 2 years or more.

(2)   Cytologic (based on predominant cell type)

(a)   Granulocytic or myelocytic – involves the granulocytes and their precursors

·  Acute myeloid / acute myeloblastic – myeloblasts predominate

·  Chronic myeloid / chronic granulocytic / chronic myelogenous – predominance of myelocytes, neutrophils, metamyelocytes and relatively few myeloblasts

·  Promyelocytic – atypical promyelocytes predominate

·  Myelocytic – myeloblasts are numerous and abnormal proliferation is evident in developing granulocytes as well as monocytes

·  Erythroleukemia or Di Guglielmo’s syndrome – a variant of acute granulocytic leukemia which refers to an abnormal proliferation of both erythroid precursors and granulocytic precursors.

·  Eosinophilic – predominance of eosinophilic immature myeloid cells.

(b)   Lymphocytic or lymphoid

·  Acute lymphoid / acute lymphoblastic / acute lymphocytic – lymphoblasts predominate

·  Chronic lymphoid / chronic lymphocytic – small mature lymphoid cells predominate

(c)    Monocytic – involves monocytes and their precursors

·  Acute monocytic – promonocytes and monoblasts predominate

·  Acute monocytic Schilling type – a pure monocytic leukemia with monocytes derived from the RES with no evidence of abnormality in granulocyte development

·  Acute monocytic Naegli type – the same as myelomonocytic

(d)   Erythroblastic

·  DiGuglielmo’s syndrome

·  DiGuglielmo’s disease or erythroblastemia or Erythremic myelosis

(e)   Stem cell leukemia or blast cell or hemoblastic leukemia – a variety of acute leukemia in which the predominant cells are primitive undifferentiated leukocytes that cannot be classified as one of the three blast form.

(f)    Plasma cell leukemia – predominance of plasma cells; this can be regarded as a leukemic form of myeloma.

(g)   Mast cell leukemia – predominance of mast cells or tissue basophils

(h)   Histiocytic leukemia / reticuloendothelial cell leukemia / hairy cell leukemia / myeloid reticulosis / leukemia reticuloendotheliosis – predominance of histiocytes

(i)     Thrombocytic or megakaryocytic leukemia or hemorrhagic thrombocythemia – predominance of thrombocytes with the presence of giant platelets and megakaryoblasts

(j)     Megakaryoblastic leukemia or acute myelofibrosis – predominance of megakaryocytes or megakaryoblasts

(k)   Basophilic leukemia – predominance of basophils

(l)     Lymphosarcoma cell leukemia – predominance of lymphosarcoma cells. These are lymphocytes and their precursors in the lymph nodes

(3)   Classification based on functional capacity of release mechanism

(a)   Leukemic leukemia – presence of immature or abnormal cells with WBC count greater than 15,000/ul

(b)   Subleukemic leukemia – with immature or abnormal cells in peripheral blood and with WBC count less than 15,000/ul

(c)    Aleukemic leukemia – with no immature cells in the peripheral blood and WBC count less than 15,000/ul

(4)   Classification based on localized proliferation of cell of the same type

(a)   Chloroma – a type of myeloblastic leukemia where there is formation of tumors originating from periosteum, especially in skulls, orbits, nasal sinuses, ribs and vertebrae. The sectioned surface of the tumor shows a green color and contain a large amount of verdoperoxidase and of protoporphyrin

(b)   Myeloblastoma – a localized tumor of myeloblasts which differs from chloroma only by the absence of pigment

(c)    Myeloma – there is a local tumorous proliferation of plasma cells in the marrow

(d)   Lymphoma – there is proliferation of one of the cell types of the lymphoetic reticular tissue. Usually, it begins in and involves lymph nodes predominantly, though other sites such as spleen, GIT are frequent area of origin as well.

Laboratory tests for the investigation of leukemia

(a)   Leukocyte count

(b)   Erythrocyte count

(c)    Platelet count

(d)   Hemoglobin determination

(e)   Cytochemical staining technique

·       Sudan Black B stain

·       Peroxidase stain

·       Esterases

·       Periodic Acid – Schiff Reaction

·       Acid Phosphatase

·       Neutrophil Alkaline Phosphatase (NAP)

·       Other special staining techniques

(f)    Hematocrit determination

(g)   Differential leukocyte count

(h)   Test for abnormal hemoglobin

(i)     Examination of blood film

(j)     Bone marrow examination

(k)   Serum protein estimation

(l)     Chromosome study

b.     Leukemoid Reaction

Leukemoid reaction is a reactive but excessive leukocytosis characterized by the presence of immature cells (e.g. blast, promyelocytes, and myelocytes) in the peripheral blood. The majority of leukemoid reactions involve granulocytes but occasionally lymphocytic reactions occur.

In leukemoid reaction, the peripheral blood picture is such as to raise the suspicion of leukemia. Severe infection, hemolytic anemias, tuberculosis, carcinomatosis, infestation with Trichinella spiralis are some of the causes of leukemoid reactions. Depending of the predominant cell, leukemoid reactions may be neutrophilic, eosinophilic, lymphocytic or monocytic.

Test employed in the differentiation of leukemoid reaction and leukemia

·       Bone marrow examination

·       Biopsy of lymph node

·       NAP or LAP test

Leukemoid reaction = high NAP score

Leukemia = low NAP score

2.     Myeloproliferative disorders

The myeloproliferative disorders comprise a group of closely related syndrome characterized by self–perpetuating proliferation of bone marrow cells; erythroid precursors; granulocytes, monocytes and megakaryocytes. The proliferation is abnormal and the cause is unknown (idiopathic). All cell lines may be involved in the proliferative process (panmyelosis), or single cell line may predominate.

(a)   Acute myeloproliferative disorders include the subgroups of acute myeloid leukemia: myeloblastic, promyelocytic, myelocytic, and the DiGuglielmo syndrome (erythremic myelosis and erythroleukemia).

(b)   Chronic myeloproliferative disorders include polycythemia vera (PV), myelofibrosis with myeloid metaplasia (MMM), thrombocythemia, and chronic myelogenous leukemia (CML). A related group of disorders are the myelodysplastic or dysmyelopoeitic syndromes.

3.     Lymphoproliferative disorders

The lymphoproliferative disorders represent a group of neoplastic conditions originating from cells of lymphoreticular system. When neoplastic cells involve predominantly the blood and bone marrow, the condition is called leukemia. However, when the condition is predominantly limited to lymph nodes and / or organs, the disorder is called lymphoma. Occasionally, lymphomas may develop into leukemia.

a. Acute lymphoid leukemia

b. Chronic lymphocytic leukemia

c. Hairy cell leukemia (leukemic reticuloendotheliosis)

d. Mycosis fungoides and Sezary’s syndrome is a lymphoreticular neoplasm primarily involving the skin. As the disorder evolves, neoplastic cells infiltrate the lymph nodes and other visceral organs

Occasionally, atypical mononuclear cells with cerebriform nuclei are present in the peripheral blood. In addition, when lymphocytosis exists (especially in the erythremic patients), the disorder is called Sezary’s syndrome.

e. Malignant lymphoma is a neoplastic proliferation of one of the cell types of the lymphoetic – reticular tissue

Hodgkin’s disease is generally regarded as a malignant lymphoma, but has different histology in that the cells reacting to the neoplasm usually predominate rather than the neoplastic cells themselves. The hallmark of Hodgkin’s disease is the Reed–Sternberg cell which is a large binucleated or multinucleated cell with wash nucleus bearing a very large nucleolus

4. Plasma cell dyscrasias and lymphoreticular malignancies associated with abnormal immunoglobulin synthesis

a. Multiple myeloma or Plasmacytoma or Kahler’s disease

Multiple myeloma is a neoplastic proliferation of plasma cells or morphologically abnormal plasma cells (myeloma cells) primarily occurring in the bone marrow either in nodules or diffusely. Though plasma cells also proliferate in lymph nodes and spleen, these organs are rarely enlarged.

Often, in multiple myeloma, a few plasma cells are found in the peripheral blood. Only in rare instances of myeloma in which large numbers of plasma cells circulate, is the term plasma cell leukemia used. Patients with plasma cell leukemia tend to have tissue infiltration, advanced stage disease and poor survival.

b. Waldenstrom’s macroglobulinemia or Primary macroglobulinemia

This is an uncommon condition which behaves clinically as a slowly progressive lymphoma. There is proliferation of cells which produce a monoclonal IgM paraprotein and bear some resemblance both to lymphocytes and plasma cells.

c. Heavy chain diseases

These are rare syndromes characterized by the production of gamma, alpha or heavy chain immunoglobulin and soft tissue tumors appearing histologically either as malignant lymphoma of plasmacytoma.

Other Leukocytic Disorder:

a. Infectious Mononucleosis or Glandular Fever or “Kissing” disease

This is a disease characterized by fever, sore throat, lymphadenopathy and atypical lymphocytes in the blood. These are thought to be a T–cells reacting against B–lymphocytes infected with Epstein–Barr (EB) virus. The condition is associated with a rising titre of antibody against EB virus. The disease is associated with high titre of heterophile antibody reacting with sheep red cells.

b. Histiocytosis

The “histiocytoses” represent a group of disease with normal proliferation of mesenchymal cells that are closely related to phagocytic histiocytes and to fat cells. Diseases of this group are due to inborn errors in metabolism genetically transmitted and more often are described in people of Jewish parentage.

1.     Lipid histiocytosis of the keratin type or Gaucher’s disease

2.     Lipid histiocytosis of the phosphatide type – Nieman–Pick disease

3.     Lipid histiocytosis of the cholesterol type – Schuller–Christian disease

c. Lupus erythematosus (LE) cell phenomenon

Systemic lupus erythematosus (SLE) is a collagen disease which affects women most commonly characterized by skin rash, arthralgia, fever, renal, cardiac and vascular lesions, anemia, leukopenia, and often thrombocytopenia. In the serum and plasma of the patient, abnormal immunoglobulins are present. Three types of anti–nulear antibodies (ANA) are noted in the blood, namely: (a) anti–DNP, (b) anti–DNA, (c) anti–nuclear extractable antibody.

Of these three, the anti–DNP is the one which produces the LE cell phenomenon. The anti–DNP causes depolymerization of the nuclear chromatin of polymorphonuclear leukocytes, and this depolymerized material is subsequently phagocytosed by an intact polymorph and occasionally monocyte of eosinophil. The phagocyte with the ingested material gives rise to the L.E. cell.

Nucleophagocytosis is a fairly common finding and is fundamentally different from an L.E. cell phenomenon. In this case, the phagocyte is more frequently a monocyte and occasionally, a granulocyte. The phagocytized nucleus or a whole cell (usually a lymphocyte) retains the intact chromatin pattern. The cell in nucleophagocytosis is called “Tart” cell. This may be present in the blood of patients who are sensitive to certain drugs.

Demonstration of L.E. cells

Usually, for L.E. cell examination, buffy coat smears are prepared by means of one of the methods enumerated below and then stained in the usual manner with Romanowsky stain and then examined microscopically.

1.     Clotted blood

a.     Zimmer and Hargraves method

b.     Magath and Winkle method

10 ml clotted blood is placed in the water bath at 37^oC for 1 to 2 hours. After incubation, the supernatant and loose cells are withdrawn and buffy coat smears are made. Alternatively, the whole clotted specimen after incubation may be mashed through a fine wire sieve and buffy coat smear is made from the resultant cell suspension.

2.     Rotary method by Zinkham and Conley

Five glass beads 3 mm in diameter are added to heparinized blood. The tube is then rotated at 50 rpm for 30 minutes, at 37^oC. Buffy coat smears are subsequently prepared.

3.     Slide method – Snapper and Nathan’s or the Indirect method

4.     Capillary L.E. cell test by Mudrik – this method uses the capillary tube

Note:        

Defibrinated, citrated or heparinized blood may be used, and then incubated as

for clotted blood.