Lymphadenopathies Flashcards
Where does VDJ rearrangement (somatic recombination) of B cells occur?
BM
After somatic hypermutation in BM, B cells go to:
Interfollicular/pericortical areas of lymphatic tissues
What three things occur in germinal center?
Antigen presentation, somatic hypermutation, class switching
What is Bcl-2?
Anti-apoptotic gene expressed by B cells in germinal centers that are selected to mature
What happens to B cell after maturation in germinal center?
Moves out to periphery to be plasma cell or memory B cell
Would you expect to find naive B cells in periphery?
Yes, small amount kept just outside mantle zone in marginal zone
What presents antigen to B cells in germinal centers?
FDC
Where does T cell gene rearrangement occur?
Thymus
Where does T cell antigen presentation occur?
Paracortex of lymph nodes/lymphatic tissues
What are tingible macrophages? Where are they found?
Macrophages in GC that clean up dead B cells which did not react with antigen/reacted with self antigen
Stain lymph node with CD20 mab. Where would you expect to see binding?
GC and mantle zone (B cells)
Stain lymph node with CD10 mab. Where would you expect to see binding?
GC (some B cells)
Stain lymph node with CD5/3 mab. Where would you expect to see binding?
Paracortex (T cells)
Infection or malignancy: Swollen, painful nodes
Infx
Infection or malignancy: Swollen node + weight loss + anemia
Malignancy
Infection or malignancy: Two nontender, swollen nodes
Malignancy
Reactive follicular hyperplasia associated with:
Bacterial infx
Paracortical expansion typical of what type of diseases?
Viral infx
Two causative agents of infectious mononucleosis:
CMV and EBV
Peripheral blood of pt with infectious mononucleosis would look like:
Large mononuclear (no shit) cells with big nuclei
What are the large, mononuclear cells seen in PB of infectious mononucleosis? What’s their function?
T cells attacking EBV-infected B cells and pharyngeal epithelial cells
Reactive T cells of infectious mononucleosis reside in:
Paracortex
Which two cells types would you expect to be most elevated on CBC on pt with infectious mono?
N. segs and lymphocytes
Pt with fever, malaise, knots in neck, anorexia, cold sweats, pharyngeal exudate. What test would you order?
Monospot for inf mono
As well as causing inf mono, EBV has been implicated in which three other diseases?
Burkitt’s Nasopharyngeal carcinoma Lymphomas in immunosuppressed pt
Key lymph node finding in patient with SLE?
Lupus lymphadenitis: zones of necrosis (cells’ nuclei will no longer stain)
Characteristics of dermatopathic lymphadenopathy
Small germinal centers with prominent mantle zones
Cells with lots of clear space (cytoplasm) and dark pigments (melanin) = histiocytes
What’s a histiocyte?
Skin-based macrophage
Why do the aggregates of histiocytes in dermatopathic lymphadenopathies have dark pigments in them?
Lymph nodes receive lots of drainage from skin lesions, which contains dead skin cells that contain melanin
Three diseases in which you would expect to see aggregates of histiocytes in lymph nodes:
Pemphigus
Eczema
Psoriasis
(any chronic skin disease)
Where would one expect to see lymph nodes with histiocytes in pt with dermatopathic lymphadenopathy?
Proximal to the lesion
Normal or reactive?
Normal - Normal size and appearance of germinal centers in the cortex, surrounded by a lymph node capsule and adjacent peri-lymph node adipose tissue.
Normal or reactive?
Reactive -F ollicular hyperplasia. Multiple large and small follicles with deeply stained mantle zones.
Infectious mononucleosis (large, reactive T cells attacking infected B cells and pharyngeal epithelial cells)
Burned out follicles
HIV (late phase)
Why does late phase HIV cause follicular burn out of lymph nodes?
CD4+ required for normal germinal centers
What does lymph node look like in late phase HIV?
No germinal centers
Histiocytes replace germinal centers
Heterophile Abs
Inf mono
What is lymphadenitis?
Increased number of WBCs in lymph nodes, usually due to infx or inflammation
