LEUKOPENIA
--Usually low neuts but sometimes lymphopenia
--ETIO: congenital, advanced HIV, post glucocorticoid or cytoctoxic drug therapy, autoimmune, malnutrition, certain acute viral infx
--Pathogenesis: decreased production or increased removal from circ
--BM is hypercellular except with agranulocytosis (aplastic anemia)--> hypocellularity
--S/Sx: regional LAD, infx often appear as ulcerating necrotizing lesions of gingiva, mouth floor, buccal mucoas, pharynx, less often in skin, vagina, anus or GI, if present in lung or UTI/kidney may be fatal
Causes of reduced NEUT production:
1) suppression of myeloid stem cells: aplastic anemia, infiltrative marrow dz
2) drug suppression of granulocytic precursors: alkylating agents->DNA miscoding, antimetabolites used in cancer Tx, aminopyrine (antifolate), sulfonamides (immune mediated)
3) Defective precursors dt megaloblastic anemia, myelodysplastic syndromes
4) genetic defects (Kostmann syndrome)
Causes of increased NEUT removal:
1) immune mediated: SLE, drugs
2) splenic sequestration (enlarged spleen)
3) increased periopheral utilization (overwhelming infx by bact, fungi or rickettsia (Rocky Mtn Spotted Fever)
LEUKOCYTOSIS = increased # of WBC's in PB
--severe infx or bacterial sepsis-->toxic granulation (reactive change)
--more reactive change: Doehle bodies, blue cytoplasmic patch of dilated ER
--usu some bands seen
--colony stimulating cytokines: IL-1, TNF
--IL-5-->more EOS
--IL-7-->more LYMPHs
CAUSES:
--increase release from marrow dt endotoxemia (bacteria), acute infx, hypoxia, acute inflam, necrosis, MI
--decreased margination dt exercise, epinephrine
--decreased extravasation into tissues dt glucocorticoid therapy
--increased numbers of marrow precursors dt chronic infx/inflam, tumos, myeloproliferative dz
LYMPHADENITIS = LAD
--chronic, nonspecific
--follicular hyperplasia
--follicle contains G cell rich germinal center with light and dark zone, surrounded by dark crescent "mantle", also macrophages containing nuclear debris (tinigle bodies, looks like large white macrophage in densely packed B cells)
PARACORTICAL LYMPHOID HYPERPLASIA
--stim by drugs, viral infx
--T-cell region of node activated
--sometimes see macrophages and EOS
SINUS HISTOCYTOSIS = RETICULAR HYPERPLASIA
--distension and prominence of lymphatic sinusoids
--nodes draining cancers, ie. carcinoma of the breast
--lymph nodes are NON-TENDER