Disorders of red blood cells, spleen, thymus (Puttoff) Flashcards
what is in the red pulp of the spleen
Constitutional symptoms
fever, night sweats, or weight loss (tuberculosis, lymphoma, or other malignancy)
fever (majority of the infectious diseases)
Use of medications that can cause lymphadenopathy
what is in the white pulp of spleen
where T cells and B cells are located – B cells found in the germinal center
what are the 4 main functions of the spleen
• Phagocytosis of blood cells and particulate matter
• Antibody production
o Antibody secreting plasma cells are the in the sinuses of the red pulp mainly
o Includes antibodies against microbials, and autoantibodies
• Hematopoiesis
o During fetal development – minor site of hematopoiesis
o Compensatory extramedullary hematopoiesis in severe chronic anemia
• Sequestration of formed blood elements
o With splenomegaly→ more platelet mass is held producing thrombocytopenia.
o Enlarged spleen can also trap white blood cells and induce leukopenia
harbors 30-40% of platelet mass in the body (with splenomegaly up to 80-90% of platelets can be sequestered → thrombocytopenia)
what is nonspecific acute splenitis
Enlargement of the spleen in any blood-borne infection
Enlarged spleen and soft
Acute congestion of the red pulp- which can encroach on and efface the lymphoid follicles
Neuts, plasma cells, eosinophils are usually present
When the agent is strep, commonly the white pulp follicles may undergo necrosis
what are the causes of congestive splenomegaly
–Chronic venous outflow obstruction → leads to splenic or portal vein HTN.
–Systemic or central venous congestion → seen in right heart failure
Cirrhosis of liver
Obstruction of extrahepatic portal vein or splenic vein → casued by spontaneous portal vein thrombosis (can be caused by infiltrating tumors from neighboring organs- stomach or pancreas)
what are the findings in congestive splenomegaly
what type of hemolysis might be found?
Marked enlargement of spleen
Thickened and fibrous capsule
Red pulp becomes fibrotic over time
Deposition of collagen in the basement membrane of sinusoids
Because there is slowing of blood flow from the cords to the sinusoids there is prolonged exposure of red blood cells to macrophages→ excessive destruction (hypersplenism)
what is the cause of splenic infarcts…
what do they look like
Usually caused by the occlusion of the major splenic artery
There is lack of collateral blood supply which predisposes the spleen to infarction following vascular occlusion
Bland infarcts→ pale, wedge-shaped, subscapular in location. Capsule is covered with fibrin
Septic infarcts→ suppurative necrosis. Large scars develop with healing
Infarcts are often from the heart**
Common in pt’s who have infectious endocarditis of the mitral or aortic valves
what are the 2 most common types of neoplasms in the spleen
lymphangiomas
hemangiomas
- can be found anywhere in the abdominal cavity
- of great clinical importance in hereditary spherocytosis, and immune thrombocytopenia purpura
accessory spleen
congenital anomaly of spleen
what might cause splenic rupture
are chronically enlarged or acute enlarged spleens more likely to rupture
Usually precipitated by blunt trauma
Spontaneous rupture→ usually there is previously abnormal spleen → infectious mononucleosis, malaria, typhoid fever, lymphoid neoplasms:
- these cause the spleen to enlarge rapidly producing a thin capsule that can rupture easily
- perform splenectomy to prevent death from blood loss
Chronically enlarged spleens are less likely to rupture b/c of toughening/fibrosis of capsule
what types of cells are in the thymus
Thymic epithelial cells (form Hassall’s Corpuscles in medulla),
immature T lymphocytes
morphology of cortical peripheral epithelial cells
polygonal and have abundant cytoplasm with dendritic extensions.
morphology of medulla epithelial cells
Medulla epithelial cells are densely packed and have spindle-shaped, scant cytoplasm, no interconnecting processes
thymic hypoplasia
DiGeorge syndrome- defects in cell mediated immunity and variable abnormalities of parathyroid development , 22q11 deletion
thymic cysts
- what lines these cysts
- what should you do if you find a cyst
discovered incidentally
- rarely exceed 4 cm
- lined by stratified to columnar epithelium
***presence of a cystic thymic lesion in a symptomatic pt should provoke a thorough search for a neoplasm (thymoma or lymphoma)
what occurs with thymic hyperplasia
what types of diseases/settings does this occur in
what are these often mistaken for
Appearance of B cell germinal centers within the thymus- thymic follicular hyperplasia
Occurs in:
- chronic inflammatory states
- Myasthenia gravis- 65-70% of cases
- SLE
- Graves
- RA
- Sclerodoma
May be mistaken radiologically for a thymoma leading to unnecessary surgical procedures
what cell type makes up thymomas
thymic epithelial cells
what are the clinical features, etiology and location of thymomas
In all categories:
- adults older than 40
- rare in children
- males = females
- most arise in anterior superior mediastinum**
- sometimes occur in neck, thyroid, pulmonary hilus, or elsewhere
- uncommon in posterior mediastinum
40% present with symptoms stemming from impingement on mediastinal structures***
Another 35-40% are detected in the course of evaluating pt’s with myasthenia gravis ***
22q11 deletion
DiGeorge syndrome
tumors that usually have a substantial portion of medullary type epithelial cells are usually
noninvasive
medullary type epithelial cells or mix of medullary type + cortical type
sparse infiltrates of thymocytes
makes up 50% of thymomas
tumors that are cytologically benign and non invasive
thymoma
penetrates through the capsule into surrounding structures
epithelial cells are more likely to be cortical type –> abudant cytoplasm, rounded vesicular nuclei and mixed with numerous thymocytes
neoplastic cells may show atypia
20-25% of all thymomas
Tumors that are cytologically benign but invasive or metastatic
what are the survival rates for tumors that are cytologically benign but invasive or metastatic
Extensive invasion → 5 year survival of less than 50%
With minimal invasion, complete excision yields 5 year survival of >90%
Tumors that are cytologically malignant (thymic carcinoma)
5% of thymomas
Fleshy, invasive masses, sometimes accompanied by metastases to sites like lungs
- Most are squamous cell carcinomas
- About 50% of these contain monoclonal EBV genomes
Atypia