Morphologic, immunphenotypic and clinical discriminators between T-cell / histiocyte-rich large B-cell lymphoma and lymphocyte-predominant Hodgkin lymphoma

Features of T-cell/histiocyte rich large B-cell lymphoma [THRLBCL] overlap with those of lymphocyte predominant Hodgkin lymphoma [LPHL]. The two lymphomas may represent a spectrum of the same disease, and differentiation between the two can sometimes be difficult. We looked at histomorphologic, immunophenotypic and clinical information that may help differentiate the two entities. Cases of THRLBCL and LPHL were blindly reviewed and studied for histological pattern [nodular vs. diffuse], nuclear features and pattern of expression of CD20, CD30, CD57, epithelial membrane antigen [EMA] and Epstein-Barr virus [EBV]. A score encompassing diffuse histology, high nuclear grade, CD20 single-cell pattern, CD30+, CD57-, EMA-, and EBV+ was estimated for the diagnosis of TCHRLBCL. There were 58 cases, including 30 cases of TCHRLBL and 28 cases of LPHL. The median age was 36 years for TCHRLBCL and 21 years for LPHL [P=0.0001]. Three types of nuclei were identified [lymphocytic/histocytic, Reed-Sternberg and centroblast-like]. The latter two high-grade nuclei were suggestive of TCHRLBCL. TCHRLBCL and LPHL, respectively, showed diffuse histology, 90% vs. 4% [P=0.001], single CD20+ cells, 93% vs. 3.5% [P=0.00004], CD30+ cells, 30% vs. 0% [P=0.01], CD57+ cells, 41% vs. 93% [P=0.008], EMA+ cells, 27% vs. 60% [P=0.113], EBV+ cells, 24% vs. 0% [P=0.117], high nuclear grade, 70% vs. 0% [P=0.001], total score 2-7 [mean 4.68] vs. 0-2 [mean 0.72] [P=0.001], high stage, 86% vs. 7% [P=0.0001]. Our findings indicate that a combination of multiple parameters can help differentiate between the two diseases. Two cases originally diagnosed as LPHL were re-assigned the diagnosis of THRLBCL

Grading of follicular lymphoma using flow cytometry

The treatment and prognosis of follicular lymphoma [FL] is dependant on the grade of the disease. In the World Health Organization classification of lymphoma, grading of FL into low grade [1 and 2] and high grade [3] is recommended. Grading of FL is possible in excision biopsy; histological grading is subjective and inconsistent Grading is extremely difficult in needle core biopsies and fine needle aspirates. We attempted to grade FL using flow cytometry [FCM] and CD 19/forward scatter. Cases of FL seen in our institution and submitted for FCM were evaluated for the percentage of cells detected beyond the 500-channel mark [on a 1024 scale] on a CD19/forward scatter dot plot. We hypothesized that these cells most likely represent centroblasts and their percentage would reflect the grade of the disease. Histological grading of the lymphoma on the open biopsies constituted the reference for FL grade. Thirty-six cases of FL, including 22 males and 14 females, ranging in age from 19 to 92 years [median, 42 years], were studied. There were 17 cases of low grade [grade 1; n=10 and grade 2; n=7] and 19 cases of high grade [grade 3] FL The percentage of cells identified beyond the 500-channel mark on CD19/forward scatter dot plot ranged from 0.12% to 12.55% [median, 4.9%] in low grade [grade 1 and 2] whereas the percentage of those cells in high grade FL ranged from 6.22% to 51.95% [median, 21%; p=0.00001]. Our findings suggest that using a CD19/forward scatter dot plot can help identify centroblasts in FL making grading possible on FCM, especially in small biopsies and fine needle aspirates