Spleen

Functions of the spleen 1. Haematopoiesis 2. Reservoir – storage or sequestration of plt and other cells 3. Phagocytosis 4. Immunity

Spleen Pulp White – follicles, PALS Red venous sinuses (littoral cells – special endothelium, discontionuous, also histiocytic markers) cords of Billroth - macrophages Marginal zone

Spleen Splenomegaly A. Symptom of a disease B. Causes discomfort C. Ruptures easily

Splenomegaly a sign of an underlying disease a problem per se bigger spleen~ bigger function = destruction of blood cells Hypersplenism 1.splenomegaly 2.(pan) cytopenia 3.correction of blood cytopenia by splenectomy

Causes of splenomegaly 1. Infections (nonspecific, infect. mono., CMV, TB, typhoid, brucellosis, syphilis, malaria (!) 2. Vascular – congestion due to portal hypertension 3. Primary dis. of lymphoid and other blood elements – benign of malignant (HL, NHL, MM, myeloproliferative dis., hemolytic anemias, ITP) 4. Autoimmune (rheum. arthritis, SLE) 5. Storage dis.(Gaucher, Niemann-Pick, mucopolys.) 6. Misc.

Nonspecific acute splenitis acute splenic tumor Blood borne infections Microbes and their products S: larger, soft Hist.: acute congestion of the red pulp Less commonly: necrosis – hemolytic Streptoc., necrosis

Congestive splenomegaly Chronic venous congestion Causes: 1. systemic 2. hepatic – most common – cirrhosis, alcohol 3. disorders of the portal or splenic vein itself (spont. portal vein thrombosis – not entirely spont. – intrahepatic dosorders; inflammation of the portal vein – pyelophlebitis – intraperitoneal infections, pressure of tumours in neighboring organs

Congestive splenomegaly Gross appearance

Splenic infarcts Source of emboli: Septic infarcts:

Congenital anomalies Absence Accessory spleens – spleniculi – very common X splenosis

Rupture: danger: massive bleeding Normal spleen never ruptures spontaneously 1.Traumatic 2.Nontraumatic a. infection b. malignant infiltration Nontraumatic r. – always suspect an underlying disease – examine the patient!!! Two-tact rupture of the spleen

Thymus:cradle and school for T-cells Lymphoepithelial organ Epithelial cells – meshwork of varioous density Under the surface: closely packed Deeper: lattice containing lymphocytes Cortex Medulla – Hassal corpuscles

Thymus Hypoplasia, aplasia Di George sy – Parathyroid, heart and blood vessels, thymus developmental failure Reduced cell-mediated immunity

Thymus cysts

Thymus hyperplasia Lymphoid follicles appear Myasthenia gravis, other autoimmune dis. (SLE, RA), other inflammatory dis.

Thymomas Tumours of thymic epithelial(!) cells Lymphocytes are only a company Classifications complicated Benign thymoma – encapsulated Malignant thymoma – I – locally invasive Biologically locally aggressive, cytologically benign) II – thymic carcinoma – cytologically and biologically aggressive – sq. Cell carcinoma and others

Thymoma Localization Size Capsule Lobulated Intermixed benign T-lymphocytes Clin. symptoms: one third: myasthenia gravis mass, pressure

Thymomas - paraneoplastic sy Cushing Pure red cell aplasia Hypogammaglobulinemia dermatomyositis