| Follicular
lymphoma (nodular) is one neoplasia of B cells
of the follicular center that imitate the architectural
and cytological disposition of the normal lymphoid
follicle. Most of them happen in individuals of
adult age (6ª decade). Macroscopical appearance
of a lymph node (Fig 1).
To small increase the most characteristic fact
is the growth pattern to nodular (follicular),
at least partly, which raises sometimes differential
diagnosis with the reactive lymphoid follicles
of lymphoid hyperplasia. With the progression
of the disease the evident nodularity disappears
and become partly diffuse. Cytologically neoplasia
is constituted by a variable mixture, according
to the different degrees, of small lymphoid cells
and great cellular type (Centroblasts) similar
to the presents in the center of the normal follicle
(germinal center) (fig 2).
In all the cases of follicular lymphoma cytogenitical
anomalies practically take place. Between the
different mutations most frequent is the chromosomal
translocation t (14; 18) that implies a reordering
of the gene Bcl-2 that can originate as a sober
expression of the same one, whose product, oncoprotein
Bcl-2, is an integral protein of the mitochondrial
membrane and acts like suppressor of the apoptosis.
This protein can be detected inmunohistologically
in material fixed in formalin and included in
paraffin. It is expressed by B and T cells in
rest but not by the normal cells of the germinal
center. It appears in most of follicular lymphomas
(fig 3 left) whereas it does not appear in follicular
hyperplasia (fig 3 right), being very useful in
distinguishing reactive neoplastic follicles (hyperplasia).
It is not useful to distinguish follicular lymphoma
of other types with lymphomas of a lower degree.
Self evaluatory quiz 
Author:
Tomás Castiella Muruzábal
Servicio de Anatomía Patológica
Hospital Clínico Universitario “Lozano
Blesa”
Zaragoza
English translation by Lalit
Kumar
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