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The International Journal of the Royal Society of Thailand
Volume XV-2023

How to classify lymphoma

The following are the reflections on how to classify lymphoma.

1) By morphology alone at low magnification, good histologic sections should allow
appreciation of nodular or diffuse appearance of lymphoma cell proliferation.
Nodular growth should raise the concern of a number of specific entities of
lymphoma (Table 1). Similarly, diffuse growth also raises the possibilities of many

entities of lymphoma (Table 2). In daily practice, one will find out that sometimes
PAS stain or immunostaining helps to appreciate the growth pattern better than
H&E stain.

Table 1 Nodular growth pattern and list of some specific entities of lymphoma

Follicular lymphoma: Typically small nodules, crowded or back-to-back; may
coalesce to form larger but vague nodules (Figures 3A, 3B & 3C).

Small lymphocytic lymphoma/chronic lymphocytic leukemia: Vague nodules

(pseudofollicles) (Figure 3D) with pale center accumulation of medium and medium
to large-sized lymphoid cells or prolymphocytes (proliferation center) (Figures 3E &
3F) surrounded by smaller lymphoid cells with round dense nucleus in the whole

background.

Mantle cell lymphoma: Sometimes with vaguely nodular growth by the expansion of
small to medium-sized lymphoid cells with cleaved nuclei and small amount of
cytoplasm; may have a normal or atretic germinal center in the center creating a

mantle zone configuration (Figures 3G & 3H).

Marginal zone lymphoma: Sometimes with vaguely nodular growth by expansion of
small to medium-sized lymphoid cells with cleaved nuclei and modest amount of
cytoplasm causing “monocytoid” appearance; may have lymphoid follicle in the

center with definite mantle layer of small lymphoid cells separating the monocytoid
lymphoma cells from the germinal center (Figure

Nodal T follicular helper cell lymphoma, follicular-type: Mixture of areas like
follicular lymphoma (see above) but the lymphoma cells are medium-sized and often

have clear cytoplasm and the larger nodule like progressive transformation of
germinal center (PTGC).

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