Spleen Flashcards
Shape of spleen: HORSE
Wedge
Shape of spleen: RUMINANTS
Flat, oval
Shape of spleen: PIG
Triangular on cross section
Shape of spleen: DOG
Boot-shaped
Shape of spleen: CAT
Long & flat
Shape of spleen: BIRD
Small & round
Normal histology of CAPSULE & TRABECULAE
- Collagen
- Elastic fibers
- Smooth muscle
Normal Histology of WHITE PULP
- Periarterial lymphoid sheath (PALS)
- (T lymphocytes)
- around the central artery or arterioles
- lymphoid follicles
- (B lymphocytes)
- surrounded by marginal zone (dendritic cells, macrophages, B, T)
Normal Histology of RED PULP
-Venous sinusoids separated by cords of reticular cells with macrophages
What is the major fx of Red pulp?
Phagocytosis
What is the major fx of White pulp?
Immune
Functions of the spleen
- Blood storage
- Blood formation –EMH
- Hb breakdown –Storage of iron
- Blood filtration (abnormal blood cells/ particulate matter)
- Initiation of immune response (Ab production, Cell mediated immunity)
Causes of Ruptured spleen
- HBC
- Hemangiosarcoma
- Splenomegaly
Sequelae of Ruptured spleen
- Exanguination
- Scarring
- Splenic fragments
- Splenosis
What is Splenosis?
–
Species commonly associated with Splenic Torsion
Dogs with GDV
Pigs
In what species does splenic duplication occur?
Pigs
-incidental finding
Features of Sidero-fibrosis (Siderotic plaque)
aka Gandy Gamma bodies
- Aged dogs
- Yellow thickened elevated area on capsule
- Hemosiderosis w/ fibrosis of capsule
Mechanism of Amyloidosis
- Monoclonal Plasma cell proliferation (myeloma)
- -> fragments of Ig –> increased AL production - Chronic inflammation (ex. TB)
- -> increased serum AA proteins (acute phase proteins) –> production of AA
Features of Amyloidosis
- prominent white pulp
- Pale homogenous deposits w/in follicles
What stains help ID amyloid?
Grossly –Lugoi’s Iodine –> Deep brown
Microscopic –Congo Red –> deep orange red
Causes of Splenic Lymphoid Necrosis
- Stress (cortisol = toxic to Tcells)
- Viral infection (immunosuppressive)
- Septicemia/toxemia
- Mycotoxicosis
Microscopic appearance of Lymphoid Necrosis
“starry-sky” appearance
-Lymphocyto-lysis
Causes of Hemosiderosis
- Aging
- Hemolytic anemia
- Anemia of chronic Dz
Appearance of Hemosiderosis
Gross: Brown to Black spleen
Microscopic: Golden-brown hemosiderin-laden Mphage
Pathogenesis of hemosiderosis
RBC lysis –> Iron / globulin / biliverdin –> Iron binds APOFERRITIN–> becomes Ferritin molecule –> ferritin molecules aggregate = Hemosiderin
Acute splenic congestion (appearance / cause)
- Reddish-black to purple
- Swollen w/ blood
Causes:
- Shock
- Barbiturates
Causes of Splenic Thrombosis, embolism, infarct
- 2ndary to endocarditis
- Endothelial damage
- Septicemia
- Hog Cholera
- Thrombotic dz
- IMHA
- Purpura hemorrhagica
- Acute pancreatic necrosis
Types of Acute Splenitis
- Hemorrhagic splenitis
- Suppurative splenitis
- Necrotizing splenitis
Hemorrhagic splenitis (Appearance / causes)
aka Blackberry jam spleen
-Swollen Bloody Soft
Causes:
- Anthrax
- Erysipela Septicemia
- Hog cholera Viremia
Suppurative Splenitis (Appearance / causes)
- Swollen or nodular, Dull yellow
- Neutrophil infiltration
Causes:
- Strep. suis Septicemia
- Acanobacterium pyogenes
- Hardware Dz
Necrotizing Splenitis (Appearance / causes)
Multifocal white foci, irregular mottled areas
Causes:
- Immunosuppressive viruses
- Septicemia/ toxemia
- Toxoplasma gondii
Acute to subacute inflammation
Hyperplastic splenitis–Monocyte-Macrophage hyperplasia
- Swollen, Red, Slightly firm
- meaty consistency, bulge on cut surface
Cause:
-subacute septicemia –Salmonella
Types of Chronic Splenitis
- Chronic suppurative splenitis
2. Chronic granulomatous splenitis
Chronic suppurative splenitis
-walled off abscess
Causes:
- Caseous Lymphadenitis (sheep/goat)
- local extension from traumatic reticuloperitonitis
Chronic Granulomatous splenitis
Multifocal mottled firm nodules
OR
Diffusely swollen and firm
-necrotic center surrounded by Mphage, epitheliod cells, multinucleate giant cells, lymphocytes, plasma cells, fibrosis
Causes:
- Mycobacterium (TB)
- Tularemia
- Mycosis
- Toxoplasma
Causes of Atrophic spleen
- Aging
- Cachexia
- Stress
- Viral infection
- Septicemia/toxemia
-lymphoid depletion
Thick wrinkled capsule
Ddx for Nodular hyperplasia
- Neoplasia -Lymphoma, leukemia, mets)
- Chronic Abscess
- Granuloma
- Hematoma
- Lymphoid Hyperplasia
Neoplastic Dz
- Lymphoma
- Hemangioma/sarcoma
- Leiomyoma/sarcoma
- Metastatic neoplasia
Lymphoma
Nodular OR diffuse enlargemnt
Involving LN, Spleen, marrow, other tissue
Hemangiosarcoma (appearance/ common sites/ clinical signs)
Dark red mass
Common sites: Right atrium, spleen
Clinical signs:
- Splenic rupture
- intra-abdominal hemorrhage
- sudden death
