Spleen and Thymus Pathology

Question 1

Spleen Anatomy
White Pulp (2) Red Pulp (2)

Answer 1

White Pulp
Lymphoid follicles made of nodules with B cell germinal centers
Contains arteries surrounded by lymphocytes

Red Pulp
Made up of vascular sinusoids separated by splenic cords
Cords contain macrophages that form a filter

Question 2

Spleen Functions (4)

Answer 2

Phagocytosis of blood cells and particulates
Dendritic cells pick up Ags and lead to Ab production
Fetal or Extramedullary Hematopoiesis
Blood sequestration

Question 3

Nonspecific Acute Splenitis

Etiology, Spleen Changes (3)

Answer 3

Infections and inflammatory immune response to them

200-400 g Spleen
Hemolytic Streptococcus can cause white pulp infarction
Red pulp congestion

Question 4

Congestive Splenomegaly

Etiologies (4) Spleen Changes (2) Complication with Description (3)

Answer 4

Chronic venous outflow obstruction
Right Sided Heart Failure causes systemic congestion
Liver Cirrhosis (main cause)
Spontaneous Portal Vein thrombosis

1000-5000 g Spleen
Fibrotic red pulp

Hypersplenism:
Anemia, Leukopenia, Thrombocytopenia

Question 5

Splenic Infarcts

Main Etiology, Morphology (3)

Answer 5

Mostly via emboli from heart

Bland Infarct:
Pale, wedge shaped and subcapsular
Capsule covered in fibrin

Question 6

Most Common Benign Lesions of Spleen (5)

Answer 6

Lymphangiomas*
Hemangiomas*
Fibromas
Chondromas
Osteomas

Question 7

Splenic Congenital Anomalies

Most Common with Clinical Importance

Answer 7

Spleniculi (Accessory spleens)

Important in hereditary spherocytosis and ITP where splenectomy is method of treatment

Question 8

Thymic Hyperplasia

Most Common Description and Etiology

Answer 8

Thymic Follicular Hyperplasia:
Presence of B cell germinal centers within Thymus
Myasthenia Gravis

Question 9

Thymomas
Location, Clinical Features (2)
Morphology: Non-Invasive (2) Invasive (2) Carcinoma (2)

Answer 9

Anterior Superior Mediastinum

Mass effect fro mediastinum compression
Found incidentally or on myasthenia gravis workup

Non-Invasive:
Medullary epithelium
Sparse Thymocyte infiltrate

Invasive:
*more likely to metastasize
Cortical Epithelial cells
Penetrate through capsule

Carcinoma
Mostly Squamous cell carcinoma
Some lymphoepithelioma-like carcinoma (EBV assoc.)