Table 4.

Immunohistochemical Results, Background Lymphocytes

Marker	Thymoma Type
	A	AB	B1	B2	B3	MNT
CD57	S	S	S	S	S	S
CD3	S	+	+	+	+	+
CD5	S	+	+	+	+	+
CD20	-	+	+	-/+	-/+	+*
CD1a	-	+	+	+	+	+
CD99	-	+	+	+	+	+
Ki67/MIB1	<10%	>80%	>80%	>80%	>80%	>80%

MNT = multinodular thymoma

-/+ = variably (large numbers of intratumoral CD20+ lymphocytes in type B2 (n = 1) and type B3 (n = 3) thymomas associated with autoimmune disorder)

* = numerous large stromal CD20+ lymphoid aggregates

S = single cells