lymphatic and lymph node aspiration cytology

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1- INTRODUCTION- DEFINITION :

  • Lymph nodes are small, kidney-shaped organs, encapsulated, a few mm long (5mm à 10mm), along the route of lymphatic channels (lymph circulation).
  • Lymph nodes are peripheral lymphoid organs (said secondary ) ,sites d’immunopoièse c.a. of production dependent lymphoid cells of the & rsquo; antigen as opposed to central lymphoid organs are lymphopoiesis ie sites producing lymphoid cells independent of any antigenic stimulation.
  • They are filter lymph and play a big role in the defense of the & rsquo; vis-a-vis body microorganisms (virus, bacteria etc.…) and the spread of cancer cells.

2- LOCATION :

  • cervical Regions, axillary, inguinal.
  • pre-vertebral regions or they accompany large thoracic and abdominal vessels.
  • Folds bending members.
  • In the hilum of the thoracic and abdominal viscera.
  • At the root and between the layers of the mesentery.

3- HISTOLOGICAL STRUCTURE :

Each lymph node has to describe the four components :

  • A conjunctiva frame
  • A lymphoid parenchyma
  • The lymphatics
  • A blood Network

A- FRAMING CONJUNCTIVA : constituted by :

a- A tissue capsule :

– made of collagen fibers and elastic fibers of a few.

– lets lymphatic vessels afferent and efferent.

b- Conjunctive bays :

– interfolliculaires : that detach from the capsule, penetrate the cortical and delimit cubicles which communicate with each other in their deep part.

– intercordonnales : irregular arrangement, extend interfollicular spans and meet in a fibrous core = the HILUM.

c- a crosslinked tissue :

  • s & rsquo; inserts on the conjunctiva frame.
  • draws a large mesh frame which supports the lymphoid formations .
  • He understands : * reticulated cells = Fixed macrophages (able to mobilize and become free macrophages).

*reticulin fibers.

B- PARENCHYMA LYMPHOID :

On he distinguishes two zones duties to the distribution inégale des lymphocytes.

a- Peripheral zone = ZONE CORTICAL :

  • Dense, occupies the node peripheral region.
  • It is split into two parts :

1- an outer cortical :

  • On its surface is the SINE UNDER- CAPSULE marginal or consisting of & rsquo; a loose network of reticulated cells, reticulin fibers and macrophages.
  • The subcapsular sinus communicates with the medullary sinuses by & rsquo; intermediate cortical sinus who walk on the surface of trabeculae.
  • The outer cortical region is formed of & rsquo; lymphoid tissue into organized structures called spherical : FOLLICLES LYMPHOIOES.

2- an inner cortical : called para-cortical areas :

  • It is continuous with the outer cortical.
  • It corresponds to the thymus-DEPENDENT area or lymphocytes are T-type (LT).
  • It is devoid of lymphoid follicles.
  • It is characterized by its particular vascularization made veinlets POST- HAIR (Cubic endothelial cells) through which the cells migrate from the blood flow to the deep cortex.

3- FOLLICLES LYMPHOID :

  • They are arranged in a single layer at the periphery of the outer cortex.
  • These are spherical formations or free cell density is higher than in other regions
  • On distingue :

– primary follicles = rounded cell clusters, dense, consisting of & rsquo; LB population (in these follicles is n & rsquo; not observed immune response but an increased proliferation of LB).

– secondary follicles : correspond to modified primary follicles.

They have a clear center called germinal center ( at which the immune reaction is taking place ) surrounded d & rsquo; a dense lymphocytic crown.

b- CENTRAL ZONE ZONE = MEDULLARY :

  • Claire, it occupies the center of the node and the hilar region.
  • It consists of :

1- CORDS MEDULLARY :

*which appear as extensions of the medial cortex.

*they contain LB, plasma cells and macrophages.

*they are separated by dilated medullary cavities called Sinus .

2- SINUS MEDULLAIRES :

Their structure is comparable to that in sinus- capsular .

3- TRAVEES INTER CORDON menores :

4- SUB FUNCTIONAL PU LYMPH :

The lymphoid parenchyma of the lymph nodes is divided into three functional compartments :

A- ZONE dependent B or Zone B :

  • Corresponds to the territory of the outer cortical.
  • Colonized by the LB (largely) which are grouped into lymphoid follicles that are related to a cell array cytoplasm highly branched cells called DENDRITIC.
  • Before antigenic stimulation :
  • Zone B is organized lymphoid follicles primary (resting)
  • these follicles are made of : – small lymphocytes B

– a loose network of dendritic cells

  • After antigenic stimulation :

*appearance of lymphoid follicles with germinal center side.

*these structures have :

– a peripheral area formed as the primary follicle small LB and & rsquo; a loose network of dendritic cells .

– A central zone : characterized by :

  • LB activated : centroblastes you centrocytes
  • A denser network of dendritic cells
  • LT (5 at 10%)
  • macrophages

B- ZONE THYMO-depending ou zone T :

  • Represented by the para-cortex or predominantly LT,
  • Characterized by the presence of dendritic cells (presenting cells d & rsquo; antigens)
  • The vascularization of this area is special, made of post-capillary venules through the wall which the cells migrate from the bloodstream to the para-cortex.

C- ZONE MEDULLAIRE : rich plasma cells and macrophages .

5- VASCULARISATION :

A- VASCULARIZATION LYMPHATIC :

  • The lymph enters the lymph node by 5 at 6 RELATED lymphatic vessels which lead into the sinus under- capsular.
  • She then won the cortical sinuses that continues for medullary sinuses.
  • These confluence to form the efferent lymphatic vessel that leaves the lymph node by the hilar region.

B- VASCULARIZATION BLOOD:

  • The arteries enter the hilum, head to the follicles while walking in the trabeculae inter-cordonnales and divide into arterioles peri-follicular which in turn provide many capillaries that reach the center of each follicle and then return to the periphery and flow into a post-venule capillary.
  • Venules post- capillaries : are characterized by an endothelium (to cuboid cells) that lets the cells of venous blood into the parenchyma of the lymph node.

6- HISTPHYSIOLOGIE:

The lymph node performs several functions :

  • Filtration of lymph : capacity & rsquo; stop foreign bodies.
  • Devices not specific : phagocytosis of foreign bodies by macrophages.
  • humoral immunity : developing & rsquo; circulating antibodies by LB.
  • Cell-mediated immunity : provided by LT.

7- THE CYTOPUNCTIQN GANGLIONAIRE :

The lymph node aspiration biopsy is a simple gesture, non invasive, bit painful, easy to achieve before any lymphadenopathy ( ie any increase in size & rsquo; a ganglion ).

  • INTEREST : it often allows rapid diagnostic referral to Benin context or reaction to a tumor while imposing the realization d & rsquo; a biopsy for histological analysis .
  • TECHNIQUE : it consists of introducing a thin and short needle (25G) in & rsquo; lymphadenopathy after immobilize it between two fingers and do some back and forth accompanied by & rsquo; s rotation & rsquo; needle and achieve some smear with lymph node collected.
  • In all cases the lymph node FNA allows & rsquo; quickly orient the Diagnostic and assists in the selection of additional tests to perform.
FIGURE 1 : sagittal section of a lymph node a/general Organization b/blood and lymphatic vasculature
FIGURE 2 : SINE SUB-CAPSULE
FIGURE 3 : medullary cords and sinuses
FIGURE 4 : Aisle intercordonnale conjunctiva

DR N course. AFOUTNI – Faculty of Constantine