October 2013 - Presented by Adam Stelling, M.D.

Clinical history:

A 28-year-old woman with no significant past medical history presented with a palpable left neck mass which had been slowly increasing in size for approximately one year and was not associated with pain or other symptoms. CT imaging located the mass deep to the sternocleidomastoid measuring less than 3.0 cm. Fine needle aspiration revealed a polymorphous population of lymphocytes. An excision was performed which revealed a 2.5 cm firm tan lymph node with a homogenous fleshy white-tan cut surface.

Micro Description:

The H&E stained sections demonstrate an enlarged lymph node with a nodular architecture containing numerous regressed follicles with concentric layering of the expanded mantle zones. Hyalinized vessels are often seen penetrating the follicles. The follicles contain aggregates of large atypical cells with prominent nucleoli. The sinuses contain variable ammounts of histiocytosis.

Immunohistochemistry was performed with the following interpretation:

CD5 – Highlights T-cells in the interstitial region.
CD21 – Highlights prominent dendritic cell meshwork within the follicles.
PAX5 – Highlights B-cells of the follicles and surrounding mantle zones.
Cyclin-D1 – Negative
HHV8 – Negative

Microscopic photographs:

 Figure 1  Figure 2

Variably sized regressed follicles
and expanded mantle zones.

Prominent hyalinized vessels with
associated follicles.

 Figure 3  Figure 4

Concentric layering of the mantle       
zones (“onion skinning”).

IHC for CD21