Irrespective of the subtype and the EBV status, all BL tumours are morphologically and immunophenotypically similar and share a common gene expression signature resembling that of centroblasts
. The tumours are composed of a monomorphic population of rapidly proliferating medium-sized B-cells characterized by the expression of IgM, CD10, and BCL6 and bearing functionally rearranged and somatically mutated Ig sequences indicative of a germinal centroblast
It is known that Bcl-6 is specially expressed by GC B cells during the centroblast
phase and usually, but not consistently, in centrocytes as well .
[sup] According to immunoglobulin gene analysis, EBV-positive and EBV-negative BL revealed two distinct cells of origin, EBV-negative BL has a lower average mutation frequency than EBV-positive BL, indicating an origin in the early centroblast
for sporadic EBV-negative BL, and EBV-positive BL corresponding to the late-GC B-cells that have begun the differentiation process into memory B-cells.
Neoplastic cells include enlarged centrocytes with cleaved/irregular nuclei and inconspicuous nucleoli and centroblasts
with larger, rounder nuclei, more-open chromatin, and 1 to 3 peripheral nucleoli (Figure 2, C).
Although DLBCL can occur in childhood, the incidence generally increases with age and roughly half of patients are over the age of 60. DLBCL arises from a mature B-cell and is usually comprised of cells resembling centroblasts
or immunoblasts, which are two distinct types of activated B-cells.
Most nucleoli were prominent, often peripherally located adjacent to the nuclear membrane (centroblasts
), with few large vesicular nucleoli, solitary and centrally located (immunoblasts).
For DLBCL, lesions are characterized by an intense cellular infiltration of the lamina propria and the predominant cells resemble either centroblasts
(large noncleaved cells) or immunoblasts .
Predominantly, the neoplastic cells presented round nuclei, multilobate, or irregular folds, with looser chromatin with multiple nucleoli surrounded by membrane (centroblasts
Microscopically, tumor cells of PCNSL, most often composed of centroblasts
and less frequently of immunoblasts, infiltrate the neural parenchyma with diffuse, invasive, or perivascular growth patterns.
The histology of FL is characterized by germinal centers of B lymphocytes, predominantly centrocytes and centroblasts
with follicular growth pattern (2,5).
In Costinean study, miR-155 was up-regulated within in vitro ABC-DLBCL cell lines (OCI-Ly10, OCI-Ly3), but not in centroblasts
(CBs) and germinal centre (GC)-DLBCL cell lines .
Some lymphoid follicles had a monotonous appearance of their germinal centres, being composed predominately of centrocytes and only a few centroblasts
and lacked tingible body