Please enable JavaScript.

Coggle requires JavaScript to display documents.

HEMATOPATHOLOGY 1 - Coggle Diagram

- - - - in every lobule, medulla and cortex can be defined
        
        medulla
        
        center of the lobule
        
        clear/pink when
        stained with H&E
        
        cortex
        
        in the periphery of the lobule
        
        dark/blue when stained with H&E
  - - - IMPORTANT COEXISTENCE
      - epithelial cells in the cortex are normally polygonal and with an aboundant cytoplasm with dendritic extensions that contact adjacent cells
        
        in neoplastic conditions the epithelial cells in the cortex and medulla become similar
      - epithelial cells in the medulla are densely packed, often spindle-shaped, have a scant cytoplasm devoid of interconnecting processes
        
        there are some characteristic structures which are formed by whorls of medullary epithelial cells (HASSAL CORPUSCLES)
  - - - they are exported to the periphery after they have been educated to distinguish between self and non-self antigens
      - during adulthood the thymic production of T cells slowly declines as the organ atrophies
  - - - thymic hypoplasia
        or aplasia
        
        seen in DiGeorge syndrome, marked by severe defects in cell-mediated immunity and variable abnormalities of parathyroid development and function and associated with 22q11 deletion syndrome
      - isolated thymic cysts
        
        uncommon lesions accidentally discovered post-mortem or during surgery
        
        rarely exceed 4 cm in diameter
        
        spherical or arborizing
        
        lined by stratified-to-columnar epithelium
        
        fluid contents can be serous or mucinous, often modified by hemorrhage
      - thymic hyperplasia
        
        appearance of B-cell germinal centres within the thymys (follicular hyperplasia)
        
        it can occur in a number of chronic inflammatory and immunologic states, but mainly in myasthenia gravis
        
        sometimes, Graves disease, SLE, scleroderma, RA and other AIDs can be involved
        
        there are cases in which a morphologically normal thymus is large for the age of the patient
        
        DD: thymoma
        
        measured by weighting the thymus
        
        if the weight is higher than normal then it can be called hyperplasia
        
        thymic hyperplasia is not associated with parenchymal growth!!!
      - thymoma
        
        restricted to tumors of the thymic epithelial cells
        
        they typically contain benign thymocytes
        
        thymomas are a mixture of epithelial neoplastic cells and benign T cells
        
        the thymocytes that arise within thymomas give rise to long-lived CD4+ and CD8+ T cells
        
        WHO classification
        (based on histology)
        
        type A: elongated epithelial cells with scattered thymocytes
        
        type AB: elongated epithelial cells mixed with more roundish epithelial clls, thymocytes are more aboundant
        
        type B1 (cortical-type): dense thymocytes with very few networks of epithelial cells
        
        type B2: epithelial cells become more evident, but there is still a component of thymocytes
        
        type B3: more similar to thymic carcinoma, becaus ethere are very atypical epithelial cells and scattered thymocytes
        (most likely invasive and metastatic)
        
        classification based on the
        most important prognostic features
        
        surgical stage
        
        cytologic features of malignancy
        
        3 histologic subtypes
        
        tumors that are cytologically benign
        and non-invasive (type A and AB)
        
        tumors that are cytologically benign, but
        invasive or metastatic (type B1, B2 and B3)
        
        tumors that are cytologically malignant
        (thymic carcinoma)
        
        non-invasive thymoma
        
        types A and AB
        
        most often composed of medullary-type epithelial cells or a mixture od medullary and cortical-type epithelial cells
        
        very clear and pink in appearance at H&E
        
        spindle-shaped cells (DD: sarcoma)
        
        50% of all thymomas
        
        2 more items...
        
        invasive thymoma
        
        type B1, B2 and B3
        
        cytologically benign, but locally invasive
        
        more likely to metastasize, e.g. in the pleura (METASTASES ARE SURGICALLY REMOVED)
        
        neoplastic cells show cytologic atypia
        
        20-25% of all thymomas
        
        2 more items...
        
        epidemiology
        
        more common in adults older than 40y
        
        rare in children
        
        M=F
        
        more common in the anterosuperior mediastinum, while uncommon in the posterior mediastinum
        
        morphology
        
        macroscopically, all thymomas are similar:
        
        lobulated
        
        firm
        
        gray-white masses of up to 15-20 cm
        
        sometimes, areas of cystic necrosis
        and calcifications
        
        most of them are encapsulated (20-25% of tumors penetrate the capsule and infiltrate perithymic tissues and structures)
        
        clinical features
        
        due to impingement on mediastinal structures (40%) or myasthenia gravis (30-45%); the rest
        are discovered incidentally at imaging/surgery
        
        other AIDs include
        
        hypogammaglobulinemia
        
        pure red cell aplasia
        
        Graves disease
        
        pernicious anemia
        
        dermatomyositis-polymyositis
        
        Cushing syndrome
- - - - the white pulp is formed by follicles, which consist of an artery with an eccentric collar of T lymphocytes
        
        follicles are structures that do not have a capsule or a specific organization (aggregations of cells only)
      - at intervals this sleeve expands to form lymphoid follicles containing mainly B lymphocytes
      - there is an ill-defined interface (marginal zone)
      - the red pulp of the spleen is traversed by numerous thin-walled vascular sinusoids, separated by the splenic cords "of Billroth"
        
        their endothelial lining is discontinuous, allowing the passage of blood cells between sinusoids and cords
        
        cords contain a labyrinth of macrophages loosely connected through long dendritic processes to create both a physical and a functional filter
  - - - decreased function of the spleen due to splenectomy or autoinfarction
        
        major clinical manifestation: increased susceptibility to sepsis caused by encapsulated bacteria, e.g. Pneumococci, Meningococci, H. influenzae
        
        the decrease of phagocytic activity and antibodies production contribute to increase the risk of sepsis
        
        trauma and surgical convenience account for >50% of all splenectomies
        
        reduced splenic function is usually assessed by radiologic imaging or morphologic techniques
        
        findings suggesting hyposplenism
        
        any blood cell line may be involved:
        
        erythrocytes: poikilocytosis with target cells, acanthocytes, nucleated RBCs
        
        platelets: thrombocytosis
        
        leukocytes: lumphocytosis, monocytosis, eosinophilia
        
        congenital hypoplasia (Fanconi anemia, sickle cell disease)
        
        infiltrative disorders
        
        old age
    - - increased function of the spleen: anemia, leukopenia, thrombocytopenia (due to increased sequestration and enhanced phagocytosis)
        
        most common cause of spleen enlargement
        
        it causes dragging sensation in the LUQ and discomfort after eating (pressure on the stomach)
        
        red pulp congestion is frequently observed
        
        SPLENOMEGALY
        
        morphology
        
        the spleen is enlarged (200 to 400 g) and soft
        
        long-standing splenic congestion produces marked enlargement (up to 5000 g)
        
        the organ becomes firm, the capsule is usually thickened and fibrous
        
        microscopically, there is acute congestion of the red pulp, becoming increasingly fibrotic and cellular; neutrophils, plasma cells and occasionally eosinophils are usually present throughout white and red pulps
        
        the elevated portal venous pressure stimulates the deposition of collagen in the basement membrane of the sinusoids, which appear dilated because of the rigidity of their walls
        
        congestive splenomegaly
        
        splenic enlargement caused by chronic venous outflow obstruction
        
        possible cause: intrahepatic disorders retarding portal venous drainage or extrahepatic disorders directly impinging upon the portal or splenic veins
        
        ultimately leading to PORTAL/SPLENIC
        VEIN HYPERTENSION
        
        1 more item...
        
        caused by:
        
        infections
        
        congestion
        
        hematologic malignancies
        
        immune-related conditions
    - - common lesions caused by the occlusion of the major splenic artery or any of its branches
        
        lack of extensive collateral blood supply predisposes to infarction following vascular occlusion
        
        infarcts can be small or large, single or multiple
        
        often caused by emboli coming from the heart (in normal-sized spleens
        
        more common in markedly enlarged spleens (the blood supply is tenuous and easily compromised?)
    - - rare, except in myeloid and lymphoid tumors
        
        primary neoplasms: benign fibromas, osteomas, chondromas, lymphangiomas and hemangiomas
    - - usually precipitated by blunt trauma
        
        it may occur in the absence of a physical blow
        
        it never involves truly normal spleens
        
        most common predisposing conditions: infectious mononucleosis, malaria, typhoid fever, lymphoid neoplasms
        --> the spleen enlarges quickly, producing a thin, tense capsule more susceptible
        
        it may cause intraperitoneal hemorrhage (prompt splenectomy)
    - - a type of ectopic splenic tissue
        
        acquired condition
        
        autoimplantation of one or more focal deposits of splenic tissue in various compartments of the body
        
        potential to mimic neoplastic and non-neoplastic splenic lesions
    - - COMPLETE ABSENCE of the SPLEEN: rare and usually associated with other congenital abnormalities, e.g. situs inversus, cardiac malformations
        
        SPLEEN HYPOPLASIA: e.g., spleniculi, more common finding
        
        ACCESSORY SPLEENS: small, spherical structures, histologically and functionally identical to the normal spleen; possibly found at any site of the abdomen; mind them in particular because they can reduce the effectiveness of a splenectomy
- - - - a lot of vital organs (lungs, heart, blood vessels) are in the mediastinum
  - - - thymoma (80-85%)
        
        thymic carcinoma (10%)
        
        carcinoid
        
        NE carcinoma (5%)
        
        these tumors arise from the thymic epithelium
    - - mature teratoma
        
        seminoma
        
        malignant mixed carcinoma
        
        yolk sac tumor
        
        embryonal carcinoma
        
        choriocarcinoma (very rare)
        
        generally, found in anterior or middle compartments
        
        primary malignant forms are more common in males; mature and immature teratomas are equally distributed between the two sexes; metastatic GCTs from the testis(more commonly than from the ovaries) can present as an apparent primary mediastinal neoplasm
    - - 15% of all mediastinal neoplasms
        
        50-60% od mediastinal malignancies
        
        10% of lymphomas involve the mediastinum as a secondary site
    - - found in the posterior mediastinum
        
        20-25% of all mediastinal neoplasms
        
        in children, approximately 50% of all mediastinal masses arise in the posterior mediastinum and 50% of these are neurogenic
        
        10% of all mediastinal tumors in adults are neurogenic (posterior mediastinum)
        
        in children:
        
        neuroblastoma, intermixed ganglioneuroblastoma, ganglioneuromas
        
        in adults:
        
        schwannoma, neurofibroma, ganglioneuroma
- - - - peripheral
        
        cortical area (follicles or lymphatic nodules, mainly B cells) and paracortical area (space between one follicle and the other; mainly T cells)
        
        !!! different from the thymus,
        where only T cells are found
        
        the paracortical area is the area between one follicle and the other
        
        it is populatd mainly by T cells (T lymphocytes, vascular structures and interdigitated dendritic cells)
        
        IDCs are the APCs that correspond to the dendritic follicular cells of cortical B-areas
        
        characteristic pierced aspect conferred by the numerous dendritic interdigitate cells
        
        a clear halo around a nucleus, mostly oval
      - central
        (medulla)
        
        it consists of efferent lymphatic sinuses (emerging from the lymph node) and lymphatic cords rich in plasma cells
        
        follicles
        
        they consist of a light central germinative centre, surrounded by a darker mantle
        
        in the germinal centers B lymphocytes are found while in the mantle zone mainly T lymphocytes
        
        TRANSITIONAL ZONE
        
        between mantle zone and germinal centre
        
        it allows recognition of different shapes
        
        GC consists of larger cells (blasts) and some macrophages, phagocytosing cellular debris
        
        blasts in the GC have an unstainable clear nucleus with aboundant cytoplasm
        
        the MZ is formed by amall lymphocytes with little cytoplasm (very dark colour)
        
        GC LOOKS CLEARER THAN MANTLE ZONE
        
        types
        
        primary
        
        structures not stimulated by antigen and consist exclusively of mantle cells
        
        secondary
        
        antigen-stimulated follicles consisting of a germinal centre, a mantle zone and possibly a marginal area