Angioimmunoblastic T-cell lymphoma (AILT) (also known as "Angioimmunoblastic lymphadenopathy with dysproteinemia") is a mature T-cell lymphoma

Lymphoma

Lymphoma is a cancer in the lymphatic cells of the immune system. Typically, lymphomas present as a solid tumor of lymphoid cells. Treatment might involve chemotherapy and in some cases radiotherapy and/or bone marrow transplantation, and can be curable depending on the histology, type, and stage...

 with systemic characterized by a polymorphous lymph node

Lymph node

A lymph node is a small ball or an oval-shaped organ of the immune system, distributed widely throughout the body including the armpit and stomach/gut and linked by lymphatic vessels. Lymph nodes are garrisons of B, T, and other immune cells. Lymph nodes are found all through the body, and act as...

 infiltrate showing a marked increase in follicular dendritic cells

Follicular dendritic cells

Follicular dendritic cells are cells of the immune system found in lymph follicles of secondary lymphoid organs and tertiary lymphoid organs. They are probably not of hematopoietic origin, though they look similar to true dendritic cells due to their filiform dendritic processes, but are of...

 (FDCs) and high endothelial venules

High endothelial venules

High endothelial venules are specialized post-capillary venous swellings characterized by plump endothelial cells as opposed to the usual thiner endothelial cells found in regular venules...

 (HEVs) and systemic involvement. It is also known as immunoblastic lymphadenopathy (Lukes-Collins Classification) and AILD-type (lymphogranulomatosis X) T-cell lymphoma (Kiel Classification)

Epidemiology

The typical patient with angioimmunoblastic T-cell lymphoma (AILT) is either middle-aged or elderly, and no gender preference for this disease has been observed. AILT comprises 15-20% of peripheral T-cell lymphomas and 1-2% of all non-Hodgkin lymphomas.

Etiology

This disease was originally thought to be a premalignant condition, termed angioimmunoblastic lymphadenopathy, and this atypical reactive lymphadenopathy carried a risk for transformation into a lymphoma. Currently, it is postulated that the originating cell for this disease is a mature (post-thymic) CD4+ T-cell that arises de novo, although some researchers argue that there is a premalignant subtype of this disease. The Epstein Barr virus (EBV) is observed in the majority of cases, and the virus has been found in the reactive B-cells that comprise part of the polymorphous infiltrate of this disease and in the neoplastic T-cells. Immunodeficiency is also seen with this disease, but it is a sequela to the condition and not a predisposing factor.

Clinical presentation

Patients with this disease usually present at an advanced stage and show systemic involvement. The clinical findings typically include a pruritic skin rash and possibly edema

Edema

Edema or oedema ; both words from the Greek , oídēma "swelling"), formerly known as dropsy or hydropsy, is an abnormal accumulation of fluid beneath the skin or in one or more cavities of the body that produces swelling...

, ascites

Ascites

Ascites is a gastroenterological term for an accumulation of fluid in the peritoneal cavity.The medical condition is also known as peritoneal cavity fluid, peritoneal fluid excess, hydroperitoneum or more archaically as abdominal dropsy. Although most commonly due to cirrhosis and severe liver...

, pleural effusions, and arthritis

Arthritis

Arthritis is a form of joint disorder that involves inflammation of one or more joints....

.

Laboratory findings

The classical laboratory finding is polyclonal hypergammaglobulinemia

Hypergammaglobulinemia

Hypergammaglobulinemia is a medical condition with elevated levels of gamma globulin.It is a type of immunoproliferative disorder.- Types :...

, and other immunoglobulin derrangements are also seen, including hemolytic anemia

Hemolytic anemia

Hemolytic anemia is a form of anemia due to hemolysis, the abnormal breakdown of red blood cells , either in the blood vessels or elsewhere in the human body . It has numerous possible causes, ranging from relatively harmless to life-threatening...

 with cold agglutinins, circulating immune complexes, anti-smooth muscle antibodies, and positive rheumatoid factor

Rheumatoid factor

Rheumatoid factor is an autoantibody most relevant in rheumatoid arthritis. It is defined as an antibody against the Fc portion of IgG. RF and IgG join to form immune complexes that contribute to the disease process...

.

Sites of involvement

Due to the systemic nature of this disease, neoplastic cells can be found in lymph nodes, liver

Liver

The liver is a vital organ present in vertebrates and some other animals. It has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion...

, spleen

Spleen

The spleen is an organ found in virtually all vertebrate animals with important roles in regard to red blood cells and the immune system. In humans, it is located in the left upper quadrant of the abdomen. It removes old red blood cells and holds a reserve of blood in case of hemorrhagic shock...

, skin

Skin

-Dermis:The dermis is the layer of skin beneath the epidermis that consists of connective tissue and cushions the body from stress and strain. The dermis is tightly connected to the epidermis by a basement membrane. It also harbors many Mechanoreceptors that provide the sense of touch and heat...

, and bone marrow

Bone marrow

Bone marrow is the flexible tissue found in the interior of bones. In humans, bone marrow in large bones produces new blood cells. On average, bone marrow constitutes 4% of the total body mass of humans; in adults weighing 65 kg , bone marrow accounts for approximately 2.6 kg...

.

Lymph node

The normal architecture of a lymph node is partially effaced by a polymorphous infiltrate and residual follicles are commonly seen. The polymorphous infiltrate consists of lymphocytes of moderate size with pale/clear cytoplasm and smaller reactive lymphocytes, eosinophils, histiocytes, plasma cells, and follicular dendritic cells

Follicular dendritic cells

Follicular dendritic cells are cells of the immune system found in lymph follicles of secondary lymphoid organs and tertiary lymphoid organs. They are probably not of hematopoietic origin, though they look similar to true dendritic cells due to their filiform dendritic processes, but are of...

. In addition, blast-like B-cells are occasionally seen. A classic morphological finding is the aborization and proliferation of high endothelial venules

High endothelial venules

High endothelial venules are specialized post-capillary venous swellings characterized by plump endothelial cells as opposed to the usual thiner endothelial cells found in regular venules...

. Hyperplastic germinal centers and Reed-Sternberg cells can also be seen.

Immunophenotype

AILT typically has the phenotype of a mixture of CD4

CD4

CD4 is a glycoprotein expressed on the surface of T helper cells, monocytes, macrophages, and dendritic cells. It was discovered in the late 1970s and was originally known as leu-3 and T4 before being named CD4 in 1984...

+ and CD8

CD8

CD8 is a transmembrane glycoprotein that serves as a co-receptor for the T cell receptor . Like the TCR, CD8 binds to a major histocompatibility complex molecule, but is specific for the class I MHC protein. There are two isoforms of the protein, alpha and beta, each encoded by a different gene...

+ T-cells, with a CD4:CD8 ratio greater than unity. Polyclonal plasma cells and CD21+ follicular dendritic cells

Follicular dendritic cells

Follicular dendritic cells are cells of the immune system found in lymph follicles of secondary lymphoid organs and tertiary lymphoid organs. They are probably not of hematopoietic origin, though they look similar to true dendritic cells due to their filiform dendritic processes, but are of...

 are also seen.

Genetic findings

Clonal T-cell receptor gene rearrangements are detected in 75% of cases, and immunoglobin gene rearrangements are seen in 10% of cases, and these cases are believed to be due to expanded EBV-driven B-cell populations. Similarly, EBV-related sequences can be detected most cases, usually in B-cells but occasionally in T-cells.. Trisomy

Trisomy

A trisomy is a type of polysomy in which there are three copies, instead of the normal two, of a particular chromosome. A trisomy is a type of aneuploidy .-Description and causes:...

3, trisomy 5, and +X are the most frequent chromosomal abnormalities found in cases.