Table of Contents
Primary cutaneous follicle center lymphoma – diffuse type
LEGEND
There are two histologic subtypes: nodular or diffuse. Here is an example of a diffuse type.
Normal epidermis with a Grenz zone
Dense, diffuse pan-dermal infiltrate composed predominantly of centrocytes > centroblasts
Primary cutaneous follicle center lymphoma – diffuse type
CD10 positive (marker of follicle center differentiation; may be negative in the skin)
Primary cutaneous follicle center lymphoma – diffuse type
Bcl2 negative in neoplastic cells, but strongly positive in T lymphocytes, which is expected
Primary cutaneous follicle center lymphoma – Mixed type – Low magnification
LEGEND
Sometimes, a mixed nodular and diffuse infiltrate is observed, as in this case.
Dense dermal nodular and diffuse infiltrate predominantly composed of centrocytes > centroblasts. The neoplastic germinal centers are monomorphic: Decreased or absent mantle zone, absence of tingible body macrophages (except in diffuse type). Lack of distinct ‘light’ and ‘dark’ zones typically seen in normal germinal centers.
Normal epidermis with Grenz zone
Primary cutaneous follicle center lymphoma – Mixed type – High magnification
LEGEND
The centrocyte is a cell of variable size (small to large) with an indented nucleus.
The centroblast is a large cell with a round nucleus and a prominent nucleolus.
Numerous mitoses and apoptotic bodies are observed in this case.
Primary cutaneous follicle center lymphoma – Mixed type
These nodular infiltrates are better visualized with CD20.
Primary cutaneous follicle center lymphoma – Mixed type
Reactive CD3 expression around neoplastic cells
