LN, Spleen & Thymus

Question 1

define

• lymphadenopathy
• lymphadenitis
• lymphoid hyperplasia

Answer 1

• lymphadenopathy - lymph node swelling
• lymphadenitis - infection of the lymph nodes
• lymphoid hyperplasia - reactive increase in lymphocytes in lymph nodes

Question 2

differences between acute and chronic lymphadenitis

Answer 2

• acute: swelling + redness + TENDERNESS
• chronic: slow swelling + NONTENDER
  
  • tends to affect inguinal & axillary lymph nodes more, which drain the extremities & thus receive infections

Question 3

what are the main morphological patterns of lymphoid hyperplasia?

Answer 3

• follicular
• paracortical
• sinus

Question 4

lymphoid hyperplasia - follicular pattern

• causes?
• microscopic morphology?

Answer 4

• 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

Question 5

lymphoid hyperplasia - parafollicular pattern

• causes?
• microscopic morphology?

Answer 5

• 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

Question 6

lymphoid hyperplasia - sinus pattern

• causes
• microscopic morphology

Answer 6

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)

Question 7

rosai-dorfman disease

• cause
• microscopic morphology
• clinical presentation

Answer 7

• 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

Question 8

granulomatous lymphadenopathy

• causes
• microscopic morphology

Answer 8

• two types:
  
  • necrotizing granulomas:
    
    • common causes
      
      • TB
      • animal carried - catch scratch, tularemia, histoplasmosis
  • non-caseating granulomas
    
    • common causes - numerous, but watch out for sarcoidosis

Question 9

metastatic tumors to lymph nodes

• pathogenesis
• microscopic morphology

Answer 9

tumor cells enter afferent lymphatics, which feed into the medullary (subcapsular) sinus → medullary sinuses → medulla → cortex

Question 10

identify picture, note important features

Answer 10

lymphoid hyperplasia - follicular pattern (bacterial)

follicle w/ asymmetric mantels + large, oblong germinal centers made of dark zone (centroblasts) & light zone (centrocytes)

Question 11

identify picture, note important features

Answer 11

lymphoid hyperplasia - parafollicular pattern (acute viral)

T-lymphocytes with some activated T-lymphocytes that are 3-4x larger than others

Question 12

identify picture, note important features

Answer 12

lymphoid hyperplasia - sinus pattern

increase #/size of cells lining sinusoids + numerous macrophages (histiocytes)

Question 13

identify the picture, note important features

Answer 13

rosai-dorfman disease - sinus histiocytosis with massive lymphadenopathy

marked dilation of sinuses + intrasinusoidal histiocytes

Question 14

identify picture, note important features

Answer 14

rosai-dorfman disease - sinus histiocytosis with massive lymphadenopathy

emperipolesis: intrasinusoidal histiocytes (macrophages) that have ingested other WBCs

Question 15

identify picture, note important features

Answer 15

necrotizing granuloma

commonly caused by TB or animal-host diseases: cat scratch, tularemia, histoplasmosis

Question 16

identify picture, note important

Answer 16

non-necrotizing granulomas

common causes - many, look out for sarcoid

Question 17

identify the picture, note important features

Answer 17

metastatic tumor to lymph nodes

tumors cells travel: marginal sinus → medullary sinuses → medulla → cortex

Question 18

accessory spleen

• cause
• morphology
• clinical significance

Answer 18

• 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

Question 19

asplenia

• morphology
• clinical significance

Answer 19

• cause - congenital
• morphology - absent spleen
• clinical - often associated with heart abnormalities

Question 20

splenic granulomas

• cause
• morphology

Answer 20

• cause - fungal infections > sarcoidosis, Hodgkin’s & non-Hodgkin’s lymphoma
• morphology - see picture

Question 21

perisplenitis

• cause
• morphology
• clinical significance

Answer 21

• 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

Question 22

splenic insufficiency

• cause
• morphology
• clinical significance

Answer 22

• 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

Question 23

splenomegaly - causes

Answer 23

• hematogenous disorders - MPNs, hodgekins & non-hodgekins
• primary splenic neoplasms
• hemolytic anemia
• autoimmune disease
• infections
• congestive states
• hemophagocytic lymphohistiocytosis

Question 24

splenomegaly - morphology

Answer 24

• gross -
  
  • enlarged & firm
  • outer surface; with thickened & fibrous capsule
  • cut surface: homogenous, beefy red congested red pulp d/t hemorrhagic that becomes → fibrotic

Question 25

**congestion** leading to splenomegaly * pathogenesis? * morphology? * clinical presentation?

Answer 25

* pathogenesis: **d/t venous outflow obstruction** * _often liver related:_ * **intrahepatic disorders -** cirrhosis * **extra-hepatic disorders -** hepatic → portal → splenic veins * morphology * gross: * outer surface - enlarged firm * cut surface - red, congested * microscopic: * hypocellular + hemorrhagic * with dilated sinuses * clinical - evolves to hypersplenism → pancytopenia

Question 26

**hemophagocytic lymphohistiocytosis** leading to splenomegaly * pathogenesis? * morphology? * clinical presentation?

Answer 26

* 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**

Question 27

splenic rupture * m/c causes * sequelae

Answer 27

* causes: * m/c - **trauma, surgical intervention** * also - spontaneous (but only in abnormal spleens) * life threatening hemorrhage → splenic implants

Question 28

what are the benign tumors of the spleen?

Answer 28

* hemangioma * lymphangioma

Question 29

hemangioma * morphology * clinical relevance

Answer 29

* morphology * \< 2 cm * usually of cavernous type * clinical relevance - **most common primary tumor of the spleen**

Question 30

lymphangioma * morphology * clinical relevance

Answer 30

* morphology: * tend to be subscapular region * **lumina contain proteinaceous material** * clinical relevance * mostly seen in children

Question 31

what are the malignant tumors of the spleen?

Answer 31

angiosarcoma

Question 32

angiosarcoma * morphology * clinical relevance

Answer 32

* morphology: either single nodular, or diffuse * clinical relevance: m/c non-lymphoid malignant neoplasm of the spleen

Question 33

Answer 33

accessory spleen can be found anywhere in the abdomen

Question 34

Answer 34

perisplinitis _thick white fibrous & plaques_ (collagen) on splenic surface d/t multiple rounds on inflammation to the capsule

Question 35

Answer 35

slenomegaly * congested, red pulp that becomes fibrotic over time

Question 36

Answer 36

hemophagocytic lymphohistiocytosis → congestion activated macrophages stuffed w/ lymphocytes

Question 37

Answer 37

splenic rupture

Question 38

what are the most common sites of metastasis to the spleen?

Answer 38

* melenoma * lung * breast * gastric * pancease * liver * colon

Question 39

Answer 39

lymphangioma (benign splenic tumor) lumina containing proteinaceous material instead of RBCs

Question 40

acute thymic involution * cause * morphology

Answer 40

* cause - **extreme metabolic stress** (high cortisol levels) * malnutrition * chronic infections * immunodeficiency * premature / ill term infants * morphology - **inc lymphocyte death**

Question 41

what are the causes of * thymic hypoplasia? * thymic hyperplasia?

Answer 41

* thymic hypoplasia - Di George syndrome * thymic hyperplasia - myasthenia gravis

Question 42

thymoma - clinically features, significance?

Answer 42

* arise in middle age * M= F * most are benign * often associated with hyperplastic thymic syndromes (_unless thymic carcinoma_) * **most common primary anterior mediastinal tumor**

Question 43

thymoma - morphology

Answer 43

* gross - lobulated, encapsulated mass * microscopic - either: * **spindle type** * **epithelioid type** * **mixed type**

Question 44

what are the malignant thymomas? what are the features of each?

Answer 44

* invasive thymoma * **benign cytological features** * but, _invades thru capsule_ * thymic carcinoma * **malignant cytological features** (m/c SSC) * _NOT_ associated with myasthenia gravis

Question 45

Answer 45

benign thymoma - tan, lobulated & encapsulate mass **m/c primary anterior mediastinal neoplasm**

Question 46

Answer 46

Question 47

Answer 47

acute thymic involution - loss of lymphocytes d/t metabolic stress (in this case - cortex loss)

Question 48

Answer 48

thymic hyperplasia (myasthenia gravis)