Riassunto esame Pneumologia, prof. Centanni, libro consigliato Lymphadenitis and Splenomegaly, Robbins

SPLENOMEGALY AND LYMPHADENITIS

Spleen

The spleen is a filter for the blood and a site of immune responses to blood-borne antigens.

Anatomy and histology:

normally located in the LUQ, its weight is 150 g, it is enclosed in a thin gray connective tissue

• capsule

red pulp with dotted white pulp follicles are present

• germinal centers are identical to those seen in lymph nodes

• the lining endothelium is discontinuous, providing a passage for blood cells between sinusoids and

• cords

cords contain a labyrinth of macrophages serving to create a physical and functional filter

•

Physiology:

1) phagocytosis of blood cells and particulate matter: red cells become trapped in the cords getting

more readily phagoccytosed by macrophages;

2) Ab production: dendritic cells trap Ag presenting them to T cells → T- and B-cell interaction leads

to the generation of Ab-secreting PCs (spleen is also an important source of Ab directed against plt,

like in immune thrombocytopenia purpura;

3) hematopoiesis: normally, splenic hematopoiesis stops at birth but can be reactivated in severe

anemia

4) sequestration of formed blood elements:

- 30-40 mL of RBCs

- 30-40% of platelets normally → 80-90% with splenomegaly → thrombocytopenia

- WBCs trapping → leukopenia

5) largest unit of the mononuclear phagocyte system → involved in all systemic inflammations,

generalized hematopoietic disorders and many metabolic disturbances;

Splenomegaly

Clinical S&S:

dragging sensation in the LUQ

• pressure on the stomach, discomfort at eating

• hypersplenism characterized by pancytopenia probably due to sequestration of blood formed

• elements

Hematologic disorders associated to splenomegaly:

HL

• NHL

• MM

• myeloproliferative disorders

• hemolytic anemia

•

Neoplasms:

very rare except in myeloid and lymphoid tumors which often cause splenomegaly

•

Myeloid metaplasia:

syndrome characterized by myeloid tissue in extramedullary sites with nucleated erythrocytes and

• immature granulocytes in the circulating blood and extramedullary hematopoiesis in the liver and

spleen, as well as anemia and splenomegaly. Both a primary form (agnogenic myeloid m.) and forms

secondary to carcinoma, leukemia, leukoerythroblastosis, and tuberculosis are known.

presenza di tessuto mieloide in sede extramidollare, che nello specifico (mielofibrosi) si realizza a

• livello splenico ed epatico [cit. Onida's mail]