Spleen and Thymus Path

Question 1

splenic pulp

Answer 1

artery with eccentric collar of T lymphocytes-expands to form lymphoid nodules composed mainly of B cells

Question 2

red pulp transversed by

Answer 2

numerous thin-walled vascular sinusoids, separated by splenic cords or ‘cords of Billroth’

Question 3

endothelial lining of sinusoids

Answer 3

discontinuous-provides passage for blood cells btwn sinusoids and cords

Question 4

cords of spleen contain

Answer 4

labyrinth of macrophages loosely connected through long dendritic processes to create both physical and fxnal filter

Question 5

spleen 4 fxns that impact disease states

Answer 5

1) phagocytosis of blood cells and particulate matter
2) antiboy production
3) hematopoiesis
4) sequestration of formed blood elements

Question 6

platelets and speen

Answer 6

normally harbors 30-40% total platelet mass; with splenomegaly up to 80-90% platelet mass can be sequestered in interstices of red pulp producing thrombocytopenia

Question 7

main bacteria patients susceptible to after splenectomy

Answer 7

pneumococcus, meningococcus, and Haemophilus influenzae

Question 8

hypersplenism

Answer 8

anemia, leukopenia, thrombocytopenia, alone or in combination; likely due to sequestration and enhanced phagocytosis

Question 9

nonspecific acute splenitis

Answer 9

occurs in any blood-borne infection

Question 10

nonspecific acute splenitis morphology

Answer 10

acute congestion of red pulp which may encroach on and virtually eface the lymphoid follicles

Question 11

congestive splenomegaly

Answer 11

chromic venous outflow obstruction-intrahepatic disorders, extrahepatic disorders impinging on portal or splenic veins, cardiac decompensation, pulmonary

Question 12

congestive splenomegaly morphology

Answer 12

firm, capsule thickened and fibrous; red pulp congested early, but increasingly fibrotic and cellular with time

Question 13

bland infarcts of spleen

Answer 13

pale, wedge-shaped, subcapsular in location; overlying capsule often covered with fibrin

Question 14

septic infarcts of spleen

Answer 14

dvlp suppurative necrosis-in course of healing large, depressed scars often dvlp

Question 15

most common neoplasm ariseing in spleen

Answer 15

lymphangiomas and hemagiomas-often cavernous type

Question 16

accessory spleens

Answer 16

20-35% postmortem exams; small, spherical structures histologically identical to normal spleen

Question 17

where are accessory spleens found

Answer 17

within abdominal cavity

Question 18

most common predisposing factor to splenic rupture

Answer 18

mono, malaria, typhoid fever, lymphoid neoplasms

Question 19

thymus dvlps from

Answer 19

3rd and inconstantly 4th pair of pharyngeal pouches

Question 20

cortical. Epithelial, and peripheral cells in thymus

Answer 20

polygonal in shape and have abundant cytoplasm with dendritic extensions that contact adjacent cells

Question 21

epithelial cells in medulla of thymus

Answer 21

densely packed, often spindle-shaped, and have scant cytoplasm devoid of interconnecting processes

Question 22

myoid cells

Answer 22

muscle-like; may play role in myasthenia gravis

Question 23

DiGerorge syndrome

Answer 23

thymic hypoplasia/aplasia, variable parathyroid dvlp associations; 22q11 deletion syndrome

Question 24

thymic cysts

Answer 24

usually discovered incidentally

Question 25

thymic follicular hyperplasia

Answer 25

appearance of B-cell germinal centers within thymus

Question 26

when is thymic hyperplasia most commonly seen

Answer 26

myasthenia gravis (65-75% cases); sometimes Graves’, Lupus, scleroderma, RA, and other autoimmune diseases

Question 27

thymomas

Answer 27

tumor of thymic epithelial cells

Question 28

3 histological subtypes of thymomas

Answer 28

1) clinically benign and noninvasive

2) benign, but invasive/metastatic 3) cytologically malignant

Question 29

morphology of thymoma

Answer 29

lobulated, firm, gray-white masses up to 15-20 cm; sometimes areas of cystic necrosis and calcification; most encapsulated

Question 30

noninvasive thymomas

Answer 30

medullary-type epithelial cells or mixture with cortical-type epithelial cells; 50% thymomas

Question 31

invasive thymoma

Answer 31

cytologically benign, locally invasive; usually cortical variety with abundant cytoplasm and rounded vesicular nuclei; 20-25% thymomas

Question 32

thymic carcinoma

Answer 32

5% thymomas; usually fleshy, most squamous cell carcinomas,

Question 33

lymphoepithelioma-like carcinoma

Answer 33

rare thymic carcinoma with sheets of cells with indistinct borders-close histological resemblance to nasopharyngeal carcinoma; 50% EBV