LN, Spleen & Thymus Flashcards
define
- lymphadenopathy
- lymphadenitis
- lymphoid hyperplasia
- lymphadenopathy - lymph node swelling
- lymphadenitis - infection of the lymph nodes
- lymphoid hyperplasia - reactive increase in lymphocytes in lymph nodes
differences between acute and chronic lymphadenitis
- acute: swelling + redness + TENDERNESS
- chronic: slow swelling + NONTENDER
- tends to affect inguinal & axillary lymph nodes more, which drain the extremities & thus receive infections
what are the main morphological patterns of lymphoid hyperplasia?
- follicular
- paracortical
- sinus
lymphoid hyperplasia - follicular pattern
- causes?
- microscopic morphology?
- causes - bacterial > RA, some viral infections
- morphology
-
variably sized follicles with
- asymmetric mantels
-
large, oblong germinal centers that themselves are composed of two regions:
- dark zone = centroblasts: proliferating blast like B-lymphocytes)
- light zone = centrocytes: irregular, cleaved lymphocytes
-
variably sized follicles with
lymphoid hyperplasia - parafollicular pattern
- causes?
- microscopic morphology?
- causes - acute viral infections > some medications
- microscopic morphology: diffuse expansion of T-lymphocytes with some activated T-lymphocytes that are 3-4x larger than others
lymphoid hyperplasia - sinus pattern
- causes
- microscopic morphology
aka histiocytosis
- causes: lymph nodes that are draining tumor cells > whipple disease
- morphology:
- hyperplasia / hypertrophy of cells lining lymphatic sinusoids + presence of numerous macrophages (histiocytes)
rosai-dorfman disease
- cause
- microscopic morphology
- clinical presentation
- cause: type of sinus lymphoid hyperplasia
- microscopic
- sinuses markedly dilated, and filled with histiocytes (macrophages) that have ingested other WBCs = emperipolesis
- clinical
- m/c in children/young adults
- massive bilateral cervical lymphadenopathy*
- fever, night sweats, weight loss
granulomatous lymphadenopathy
- causes
- microscopic morphology
- two types:
-
necrotizing granulomas:
- common causes
- TB
- animal carried - catch scratch, tularemia, histoplasmosis
- common causes
-
non-caseating granulomas
- common causes - numerous, but watch out for sarcoidosis
-
necrotizing granulomas:
metastatic tumors to lymph nodes
- pathogenesis
- microscopic morphology
tumor cells enter afferent lymphatics, which feed into the medullary (subcapsular) sinus → medullary sinuses → medulla → cortex
identify picture, note important features
lymphoid hyperplasia - follicular pattern (bacterial)
follicle w/ asymmetric mantels + large, oblong germinal centers made of dark zone (centroblasts) & light zone (centrocytes)
identify picture, note important features
lymphoid hyperplasia - parafollicular pattern (acute viral)
T-lymphocytes with some activated T-lymphocytes that are 3-4x larger than others
identify picture, note important features
lymphoid hyperplasia - sinus pattern
increase #/size of cells lining sinusoids + numerous macrophages (histiocytes)
identify the picture, note important features
rosai-dorfman disease - sinus histiocytosis with massive lymphadenopathy
marked dilation of sinuses + intrasinusoidal histiocytes
identify picture, note important features
rosai-dorfman disease - sinus histiocytosis with massive lymphadenopathy
emperipolesis: intrasinusoidal histiocytes (macrophages) that have ingested other WBCs
identify picture, note important features
necrotizing granuloma
commonly caused by TB or animal-host diseases: cat scratch, tularemia, histoplasmosis
identify picture, note important
non-necrotizing granulomas
common causes - many, look out for sarcoid
identify the picture, note important features
metastatic tumor to lymph nodes
tumors cells travel: marginal sinus → medullary sinuses → medulla → cortex
accessory spleen
- cause
- morphology
- clinical significance
- cause - congenital
- morphology
- histology - normal & function normal
- gross - can be anywhere in the abdomen
- clinical:
- in 20-35% of normal persons
- clinically insignificant, except for the cases in which a splenectomy is necessary as tx: then must also remove accessory spleen
asplenia
- morphology
- clinical significance
- cause - congenital
- morphology - absent spleen
- clinical - often associated with heart abnormalities
splenic granulomas
- cause
- morphology
- cause - fungal infections > sarcoidosis, Hodgkin’s & non-Hodgkin’s lymphoma
- morphology - see picture
perisplenitis
- cause
- morphology
- clinical significance
- cause - multiple rounds of inflammation of the splenic capsule
- morphology - thick white fibrous & plaques (made of collagen) coat the the splenic surface
- clinical - incidental finding at biopsy
splenic insufficiency
- cause
- morphology
- clinical significance
- cause - splenectomy: either
- surgical
- auto: d/t sickle cell disease (causes infraction)
- morphology - n/a
- clinical - pts w/ insufficiency must be vaccinated against encapsulated bacteria:
- s. pneumonia
- m. meningitis
- h. influenza
splenomegaly - morphology
- gross -
- enlarged & firm
- outer surface; with thickened & fibrous capsule
- cut surface: homogenous, beefy red congested red pulp d/t hemorrhagic that becomes → fibrotic
congestion leading to splenomegaly
- pathogenesis?
- morphology?
- clinical presentation?
- pathogenesis: d/t venous outflow obstruction
-
often liver related:
- intrahepatic disorders - cirrhosis
- extra-hepatic disorders - hepatic → portal → splenic veins
-
often liver related:
- morphology
- gross:
- outer surface - enlarged firm
- cut surface - red, congested
- microscopic:
- hypocellular + hemorrhagic
- with dilated sinuses
- hypocellular + hemorrhagic
- gross:
- clinical - evolves to hypersplenism → pancytopenia
hemophagocytic lymphohistiocytosis leading to splenomegaly
- pathogenesis?
- morphology?
- clinical presentation?
- pathogenesis:
- m/c caused by infection - esp EBV & HIV. infections activate macrophages, which phagocytose blood cells (progenitors & mature)
- morphology
- gross: splenomegaly
- microscopic: macrophages that have phagocytized lymphocytes in splenic sinuses (like in rosai-dorfman disease)
- clinical - cytopenia, which can evolve to → DIF / shock / multi-organ failure
splenic rupture
- m/c causes
- sequelae
- causes:
- m/c - trauma, surgical intervention
- also - spontaneous (but only in abnormal spleens)
- life threatening hemorrhage → splenic implants
hemangioma
- morphology
- clinical relevance
- morphology
- < 2 cm
- usually of cavernous type
- clinical relevance - most common primary tumor of the spleen
lymphangioma
- morphology
- clinical relevance
- morphology:
- tend to be subscapular region
- lumina contain proteinaceous material
- clinical relevance
- mostly seen in children
angiosarcoma
- morphology
- clinical relevance
- morphology: either single nodular, or diffuse
- clinical relevance: m/c non-lymphoid malignant neoplasm of the spleen
accessory spleen
can be found anywhere in the abdomen
perisplinitis
thick white fibrous & plaques (collagen) on splenic surface d/t multiple rounds on inflammation to the capsule
slenomegaly
- congested, red pulp that becomes fibrotic over time
hemophagocytic lymphohistiocytosis → congestion
activated macrophages stuffed w/ lymphocytes
splenic rupture
lymphangioma (benign splenic tumor)
lumina containing proteinaceous material instead of RBCs
acute thymic involution
- cause
- morphology
- cause - extreme metabolic stress (high cortisol levels)
- malnutrition
- chronic infections
- immunodeficiency
- premature / ill term infants
- morphology - inc lymphocyte death
what are the causes of
- thymic hypoplasia?
- thymic hyperplasia?
- thymic hypoplasia - Di George syndrome
- thymic hyperplasia - myasthenia gravis
thymoma - morphology
- gross - lobulated, encapsulated mass
- microscopic - either:
- spindle type
- epithelioid type
- mixed type
benign thymoma - tan, lobulated & encapsulate mass
m/c primary anterior mediastinal neoplasm
acute thymic involution - loss of lymphocytes d/t metabolic stress
(in this case - cortex loss)
thymic hyperplasia (myasthenia gravis)
