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T-Cell Lumphomas |
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Low-grade T-cell lymphomas commonly affect the
skin and present with rashes.
Low-grade T-cell lymphomas, of which there are four main types, account for
under
10% of lymphomas in Western countries.
Small cerebriform T-cell lymphomas commonly affect the skin and draining lymph
nodes.
They are called 'cerebriform' because the nuclear membrane is very convoluted.
There are two main clinical syndromes.
In mycosis fungoides and Sézary's syndrome, neoplastic T-cells migrate into the
epidermis,
causing an erythematous rash. In Sézary's syndrome these atypical cells also
circulate
in the blood. With progression of disease, the skin develops thick plaques of
lymphoma
and there is visceral involvement.
Aetiological factors in lymphomas
Thymic hyperplasia can be associated with autoimmune disease
High-grade T-cell lymphomas are increasingly recognized by immunocytochemical
methods
In the Western world, T-cell lymphoma is one of the least common types. In the
Caribbean and
Japan these tumours are more common due to causation by human T-cell leukaemia
virus type 1 (HTLV-1).
Identification has been greatly helped by immunochemical detection of T-cell
markers.
The main types are:
• Polymorphic medium- and large-cell T-cell lymphomas. Composed of CD4 positive
T-cells, these tumours are also called 'adult T-cell leukaemia/lymphoma'. There
is frequent extensive
disease with skin involvement, hypercalcaemia and leukaemia. T-cell leukaemia/lymphoma
is often
associated with infection by HTLV-1. This virus also causes tropical spastic
paraparesis.
• Immunoblastic T-cell lymphomas are histologically similar to B-cell types.
They may evolve from low-
grade T-cell lymphomas or develop in the context of immunodeficiency.
• Lymphoblastic T-cell lymphomas are mainly seen in adolescent males, frequently
involving the thymus
and mediastinal nodes. There is rapid spread to bone marrow, lymph nodes, and
extranodal sites with
development of leukaemia. Extensive colonization of nodal and extranodal sites
dictates
the use of aggressive therapy including irradiation of the neuraxis.
• Large cell anaplastic lymphoma is composed of large cells with a superficial
resemblance to epithelial
cells. They express CD30 (formerly called Ki1) and epithelial membrane antigen.
Extranodal lymphomas are most common in mucosa-associated lymphoid tissue (MALT)
Lymphomas that arise in the tonsils, gut, bronchi, salivary glands and thyroid
are
examples of lymphomas of highly specialized MALT.
The cells that become neoplastic continue to have the same specialized homing
functions,
re-circulating only to the site of origin and the draining local nodes. They do
not become
systematized, as cells lack markers that would allow them to home in on other
sites.
The majority of MALT lymphomas are B-cell in type.
Cytologically they range from small cells to large immunoblastic-type cells.
Patients with coeliac disease may develop high-grade T-cell lymphoma of the
small
bowel as a complication of long-standing disease. |
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We give here simplified and accurate information about the disease
Info@somalidoc.com |
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