White Blood Cell Disorders

Rahul's Noteblog Notes on Pathology White Blood Cell Disorders

Useful Nomenclature:

• "-philia," "-cytosis" = increase.

• "-penia" = decrease.

WBC qualitative disorders:

• Eg., Chediak-Higashi syndrome, selectin or CD11a/CD18 deficiency.

• Microbial infections.

• Growth failure in children.

• Gingivitis.

• Job's syndrome.

WBC quantitative disorders:

Neutrophilic leukocytosis:

• Increased neutrophil count.

• Caused by infection inflammation.

• Increased production of neutrophils.

Neutropenia:

• Decreased neutrophils.

• Immune destruction.

• Decreased production.

Eosinophilia:

• High eosinophil count.

• Type I hypersensitivity, helminthic infections, polyarteritis nodosa, Addison's disease.

Eosinopenia:

• Decreased eosinophil count.

• Hypercortisolism, corticosteroids destroy eosinophils.

Basophilia:

• Increased basophil count.

Lymphocytosis:

• Increased lymphocyte count.

• Viral or bacterial infections.

• Drugs; Graves' disease.

• Increased production.

Atypical lymphocytosis:

• Infections, drugs, etc.

Infections mononucleosis:

• Caused by EBV, which attaches to CD21 receptors on B cells; stays dormant in B cells.

• Fatigue, tonsillitis.

• + heterophil antibody test.

• + antiviral capsid test.

• Increased serum transaminases from hepatitis.

Lymphopenia:

• Decreased lymphocyte count.

• HIV.

• DiGeorge, SCID.

• Corticosteroids, radiation.

• Increased destruction; decreased production and release from lymph nodes.

Monocytosis:

• Chronic infection.

• Autoimmune disease.

Leukemias:

• Bone marrow disease that involves all cell lines.

• Caused due to chromosomal abnormalities, radiation, chemicals.

• Types: ALL, AML, CML, CLL.

• Block in stem cell differentiation.

Acute leukemia:

• Fever, bleeding, fatigue.

• Bone pain, tenderness.

• Anemia, thrombocytopenia.

• Metastatic disease: liver, CNS, lymph nodes, skin.

Chronic leukemia:

• Insidious onset.

• Involved: liver, lymph nodes.

• Thrombocytopenia, anemia.

Neoplastic myeloid disorders:

Chronic myeloproliferative disorders:

• Polycythemia vera, CML, myeloid metaplasia with myelofibrosis, essential thrombocytopenia.

• Findings: splenomegaly, bone marrow fibrosis, acute leukemia.

Types of Myeloid Disorders:

• Relative polycythemia: increased RBC count due to decreased plasma volume.

• Absolute polycythemia: ectopic EPO secretion; increased RBC count and mass.

• Polycythemia vera: clonal expansion of multipotent myeloid stem cells.

• Findings: splenomegaly, gout, hyperviscosity.

Chronic myelogenous leukemia:

• 40-60 years of age.

• Radiation, benzene.

• Neoplastic clonal expansion of pluripotential stem cells.

• t9:22 translocation of ABL proto-oncogene.

• Hepatosplenomegaly, generalized lymphadenopathy.

• Blast crisis.

• Platelet count is increased or decreased.

• Positive Philadelphia chromosome.

• BCR-ABL fusion gene.

• Decreased leukocyte alkaline phosphatase.

Myelofibrosis and myeloid metaplasia:

• Marrow fibrosis.

• Neoplastic cells produced.

• Massive splenomegaly and portal hypertension.

• Splenic infarcts.

• Tear-drop RBCs.

Essential thrombocytopenia:

• Megakaryocyte proliferation.

• Increased but nonfunctional platelets.

• Bleeding, splenomegaly.

• Thrombocytosis.

• Leukocytosis.

Myelodysplastic syndrome:

• Men 50-80 years old.

• Neoplastic stem cell disorders.

• Chromosomal abnormalities.

• Pancytopenia.

• Ringed sideroblasts.

Acute myelogenous leukemia:

• 15-59 years old.

• Abnormal chromosomes; eg., t(15;17).

• DIC, Auer rods in myeloblasts.

Acute lymphoblastic leukemia:

• Newborn to 14 years old.

• CALLA, CD10, TdT markers.

• T(12;21).

• Anemia with thrombocytopenia.

Adult T-cell leukemia:

• Associated with human T-cell leukemia virus (HTLV-1).

• Activated TAX gene inhibits TP53 suppressor gene.

• Proliferation of CD4 helper T-cells.

• Hepatosplenomegaly, lymphadenopathy; skin infiltration.

• Lytic bone lesions.

• Positive CD4; negative TdT.

Chronic lymphocytic leukemia:

• Over 60 years of age.

• "Smudge cells."

• Most common leukemia.

• Lymphadenopathy.

• Immune hemolytic anemia.

• Neutropenia.

• Anemia.

• Hypogammaglobulinemia.

Hairy cell leukemia:

• B-cell leukemia.

• Splenomegaly.

• No lymphadenopathy.

• Hepatomegaly (20%).

• Autoimmune vasculitis and arthritis.