13. WBCs, LNs, Spleen, Thymus Flashcards
What is the difference between serum and plasma?
Serum is the liquid part of blood AFTER coagulation; devoid of clotting factors like fibrinogen
[plasma - fibrinogen = serum]
Distribution of red vs. yellow marrow in adults
Adult red marrow = ~50% volume; skull, facial bones, vertebrae, clavicle, sternum, ribs, pelvix, proximal femur, hands, feet
Adult yellow marrow = ~50% volume, “long bones”; humerus, ulna, radius, femur, tibia, fibula
Definitive hematopoietic stem cells arise in the mesonephros. During the 3rd month of embryogenesis, HSCs migrate to the ____ which is the chief site of blood cell formation until shortly before birth. By the 4th month of embryogenesis, HSCs shift location again, taking up residence in the bone marrow.
Liver
Physiologic and pathologic implications of extramedullary hematopoiesis
Physiologic — hematopoiesis occuring in yolk sac, liver, or spleen as part of normal immune responses (i.e., APC and phagocyte production in spleen and liver)
Pathologic — conditions in which bone marrow becomes uninhabitable for stem and progenitor cells
Thin-walled vascular structures lined by single layer of endothelial cells which are underlaid by a discontinuous basement membrane and adventitial cells; function is to allow movement of cells from hematopoietic islands in bone marrow into the vascular space
Bone marrow sinusoids
Typical procedural location for bone marrow biopsy/aspiration in adults
PSIS
Cells of lymphoid lineage
NK cells
B cells
T cells
Cells of myeloid lineage
Myeloblasts —> neutrophils Monoblasts —> monocytes Eosinophiloblasts —> eosinophils Basophiloblasts —> basophils Megakaryoblasts —> platelets Erythroblasts —> RBCs
Agranulocytosis is a clinical significant reduction in neutrophils that increases susceptibility to infection. What is the MCC?
Drug toxicity
Examples: alkylating agents, anti-metabolites, aminopyrine, chloramphenicol, sulfonamides, chlorpromazine, thiouracil, phenylbutazone
Causes of acute lymphadenitis based on location in cervical, axillary or inguinal, or mesenteric LNs
In cervical region — d/t drainage of bacteria from infections of teeth or tonsils
In axillary or inguinal regions — d/t bacteria in extremities
In mesenteric LNs — d/t appendicitis
2 Causes of chronic lymphadenitis
H.pylori
Rheumatoid arthritis
Reactive condition marked by cytopenias and signs/symptoms of systemic inflammation related to macrophage and CD8 T cell activation
Most pts present with acute febrile illness associated with splenomegaly or hepatomegaly; hemophagocytosis usually seen on bone marrow exam, labs show anemia, thrombocytopenia, elevated plasma ferritin and IL-2R, elevated LFTs and triglycerides
Hemophagocytic lymphohistiocytosis
[can be sporadic or familial; most common trigger is infection with EBV]
Virus associated with adult T-cell leukemia/lymphoma
HTLV-1
Virus found in a subset of Burkitt lymphoma, Hodgkin lymphoma, B cell lymphomas arising in setting of T cell immunodeficiency, and NK cell lymphomas
EBV
Lifestyle risk factor commonly associated with AML
Smoking
Immunostaining for _______ is present in 95% of cases of precursor B and T cell lymphomas
TdT
95% of precursor B and T cell lymphomas achieve complete remission w/ aggresive chemotherapy, but are still the leading cause of cancer death in children. What are factors associated with a FAVORABLE prognosis in this type of lymphoma?
Age between 2-10 Low white cell count Hyperdiploidy (seen in B-ALL) Trisomy of Chr 4, 7, 10 Presence of a t(12;21) \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
[Note: worse px associated w/ age <2 (associated with MLL translocations), presentation in adolescence or adulthood, peripheral blood blast counts >100,000]
Gene mutations and cell markers associated with B-ALL
Genes: PAX5, E2A, EBF, or balanced t(12;21) involving ETV6 and RUNX1
Cell markers: CD19, CD10, PAX5
70% of T-ALL presents with gain of function mutations in _______, and cell markers include ____________
NOTCH1
CD1, CD2, CD5, CD7
Most common leukemia of adults in western world
CLL/SLL
Clinical features of CLL/SLL include nonspecific sxs like fatigue, weight loss, anorexia, and mild HSM. Median age of dx is 60, affecting M>F. Hypogammaglobulinemia is common —> increased susceptibility to infection. The prognosis depends on clinical stage and median survival is 4-6 years.
What are features of a WORSE prognosis with CLL/SLL?
Deletions of 11q and 17p
Lack of somatic hypermutation
Expression of ZAP-70
Presence of NOTCH1 mutation
What is Richter syndrome?
When CLL/SLL transforms into a DLBCL, characterized by rapidly enlarging mass within LN or spleen; poor prognosis of <1 year
Proliferation centers with architectural effacement as well as presence of smudge cells
CD markers of CD19, CD20, CD23, CD5
CLL/SLL
Memory B cell lymphoma associated with t(11;18), t(1;14), or t(14;18) [MALT1 or BCL10 translocations], seen in extranodal locations in adults with chronic inflammatory diseases
Extranodal marginal zone lymphoma
Naive B cell lymphoma associated with t(11;14) —> increased levels of cyclin D1. Most express Ig with monoclonality and are CD5+, CD23-. Presents with painless generalized LAD and occasional lymphomatoid polyposis of colon.
Mantle cell lymphoma
Germinal center B cell lymphoma characterized by t(14;18) in which BCL2 is expressed in 90%; presents with painless generalized LAD and often invovles splenic white pulp and hepatic portal triads
Follicular lymphoma
Memory B cell malignancy characterized by activating BRAF mutation; usually presents in older caucasian males with pancytopenia and massive splenomegaly; associated with increased incidence of MYCOBACTERIUM and immunophenotype that includes CD11c
Hairy cell leukemia
Presents in older adults with lytic bone lesions, hypercalcemia, and renal failure secondary to chronic bence jones proteinuria (d/t tubular depositions of kappa or gamma light chains); rouleaux formation on PB smear, immunophenotype CD138 and sometimes CD56
Multiple myeloma
What are the consequences of bone marrow involvement in multiple myeloma pts?
Normocytic normochromic anemia, sometimes accompanied by leukopenia and thrombocytopenia
What causes lytic bone lesions in multiple myeloma?
Myeloma-derived MIP1-alpha regulates expression of receptor activator of NFkB ligand (RANKL) by bone marrow stromal cells, which in turn activates osteoclasts
Multiple myeloma has a variable prognosis, with worse prognosis associated with deletions of 17p or 13q, t(4;14), and high serum IL-6. A better prognosis is associated with translocations involving _____
Cyclin D1
Plasmacytomas are isolated plasma cell masses in bone or soft tissues (lungs, oronasopharynx, nasal sinuses). Solitary osseous plasmacytomas inevitably progresses to _____ ____ but can take up to 10-20+ years
Multiple myeloma
Clinical manifestations of waldenstrom macroglobulinemia (high levels of IgM leading to blood hyperviscosity)
Visual impairment d/t venous congestion, HA, dizziness, deafness, stupor, bleeding, and cryoglobulinemia (presents as Raynaud)
Most common plasma cell dyscrasia, particularly of elderly pts in US
Monoclonal gammopathy of undetermined significance (MGUS) — characterized by small to moderately large M components in blood