Infiltration of the Bone Marrow in Angioimmunoblastic T-Cell Lymphoma

T-cell angioimmunoblastic T-cell lymphomas arise from T follicular helper cells.

Parameters:

(1) positivity of immunohistochemical staining in an affected lymph node

(2) positivity of immunohistochemical stains in the bone marrow

(3) histologic pattern

Immunohistochemical stains to perform include:

(1) PD-1

(2) bcl-6

The tumor cells may stain with PD-1 and/or bcl-6.

The tumor in bone marrow may stain the same as the tumor in an involved lymph node but staining tends to be weaker.

Histologic patterns:

(1) interstitial/micronodular infiltrate with eosinophils

(2) interstitial/micronodular infiltrate without eosinophils

(3) diffuse infiltration with eosinophilia