Pathologic features of hyaline vascular histopathologic subtype of unicentric Castleman disease

(A) Two follicles are present in this field. The follicles contain small, regressed germinal centers. The follicle to the left of the field contains more than one germinal center ("twinning"). Hematoxylin and eosin stain.
(B) Hyaline deposits are present within the germinal center. Hematoxylin and eosin stain.
(C) Hyaline vascular ("lollipop") lesion in which a follicle is radially penetrated by a sclerotic blood vessel. Hematoxylin and eosin stain.
(D) The follicle is surrounded by a broad mantle zone composed of concentric rings of small lymphocytes (so-called "onion skin"). Hematoxylin and eosin stain.