Paraffin immunoreactivity of CD10, CDw75, and bcl-6 in follicle center cell lymphoma

Follicle center cell lymphoma(FCCL) has the following immunophenotype(IP): sIg+, Pan B+, CD1O+/-, CD5-, CD23-/+, CD43-, CD11c-, CD25-. In addition, re activities of a malignant lymphoma with CDw75(LN-1) and bcl-6 are considere d indicators of FCCL. Bcl-6 expression is common in Grade 1 FCCL (100%) and rare in other indolent B-cell lymphomas(BCL). In contrast, bcl-2 expressio n is common in FCCL (80%) and in other BCL subtypes. Since no previous stud y has correlated paraffin immunoreactivity(PIR) of CD10, CDw75, and bcl-6 i n FCCL (Grades 1-3), this is this study's purpose. Twenty-nine FCCL's were identified and reviewed (6, Grade 1; 10, Grade 2; 1 3, Grade 3) from the Division of Hematopathology, St. Louis University. The diagnoses were based on morphology and immunohistochemistry(IH)(21 cases) +/- the flow cytometric IP(14 cases). The paraffin blocks were stained for CD10 (Novacastra, Vector Laboratories, Burlingame, CA), CDw75 and bcl-6 (DA KO Corporation, Carpinteria, CA). Results showed that, CD10 by paraffin IH( PIH) was positive in 23 [18(strong); 3(moderate); 2(weak)] and negative in 6(3, Grade 2; 3, Grade 3). All CD10-cases were CDw75+; 4, bcl-6+. The two C D10-, bcl-6-cases were Grade 2. CDw75 was positive in 28 cases [16(strong); Il(moderate); 1(weak)] and negative in 1 (Grade 3; CD10+, bcl-2+, bcl-6+). Bcl-6 was positive in 26 [16(strong); 6(moderate); 4(weak)] and negative i n 3(Grade 2's). Thus, the sensitivity of CD10, CDw75, and bcl-6 by PM for F CCL was 79%, 97%, and 90%, respectively. Of the three stains evaluated by P IH in FCCL, CDw75 was the most sensitive, closely followed by bcl-6. CD10 w as least sensitive-79%. By combining these 3 stains, the sensitivity was 10 0%; thus, a combined approach is recommended.