In this study the authors explored the value of immunostaining for follicular center B-cell markers, BCL-6 and CD10, in paraffin sections as a tool for the differential diagnosis of B-cell lymphomas. The cases studied comprised reactive lymphoid hyperplasia (RLH; n = 19), follicular lymphoma (FL; n = 50), low-grade mucosa-associated lymphoid tissue (MALT) lymphoma (n = 24), mantle cell lymphoma (n = 19), splenic marginal zone lymphoma (n = 13), diffuse large B-cell lymphoma (DLBCL; n = 54), Burkitt's lymphoma (BL; n = 20), nodular lymphocyte predominance Hodgkin's disease (NLPHD; n = 16), and classic Hodgkin's disease (CHD; n = 13). In RLH, CD10 and BCL-6 were expressed almost exclusively by the follicular center cells. In contrast in FL, the expression of CD10 (39/50) and BCL-6 (34/36) was seen in both follicular and interfollicular neoplastic B cells. Marginal zone/MALT lymphomas and mantle cell lymphoma were always negative. In DLBCL the expression was variable for both CD10 (21/54) and BCL-6 (39/47), with some tumors, including cases of transformed follicular lymphoma (9/10), coexpressing CD10 and BCL-6, and others expressing only BCL-6, and a small group expressing neither marker, possibly reflecting the underlying primary pathogenetic events such as the rearrangement of BCL-2 or BCL-6 genes. BL was always both CD10 and BCL-6 positive. In NLPHD the L&H cells expressed BCL-6 (11/13) but not CD10, whereas in CHD BCL-6 expression was seen in half of the cases. This study demonstrates that both CD10 and BCL-6 are reliable markers of follicular center B-cell differentiation. CD10 and BCL-6 immunostaining have an important role in differential diagnosis of FL from RLH and other low-grade B-cell lymphomas. The results also suggest that a CD10/BCL-6 expression pattern may be helpful in identifying main subsets of DLBCL. However, additional studies comparing genotype with immunophenotype are required.

Loss of response to a gluten-free diet (refractory sprue) and ulcerative jejunitis are complications of celiac disease that may progress to enteropathy-associated T-cell lymphoma (EATL). Both conditions are characterized by the presence of a nonlymphomatous monoclonal T-cell population in the enteropathic mucosa. In EATL, a similar monoclonal population that shows clonal identity with the lymphoma itself is also present in the enteropathic mucosa. In this study we show that in all three circumstances the monoclonal T-cell population is constituted by cytologically normal, noninvasive intraepithelial T lymphocytes that share an identical aberrant immunophenotype with EATL. Patients with refractory sprue and/or ulcerative jejunitis are, therefore, suffering from a neoplastic T-cell disorder for which hematological treatment strategies need to be devised.

Tr1 cell numbers were elevated in the peripheral blood and increased numbers of CD4+CD25highFOXP3+ Tregs were detected in the skin of patients with AD. The epidermal dendritic cell clusters in APT-positive lesional skin showed a close connection to the FOXP3+ Tregs.

Anaplastic large cell lymphoma (ALCL) is composed of large, frequently bizarre, cells of T- or null-cell phenotype that show a preferential sinusoidal growth pattern and consistent CD30 positivity. Whether these tumors represent a single entity or several, and what the exact cell origin, is controversial. Recently, granzyme B, a cytotoxic granule component, was reported in a small percentage of ALCL, suggesting that some cases may originate from cytotoxic lymphocytes. To further investigate this possibility, we performed an immunohistochemical study of 33 ALCLs of T- and null-cell type, using monoclonal antibodies to cytotoxic cell-associated antigens, including CD8, CD56, CD57, and the cytotoxic granular proteins perforin and TIA-1. In addition, CD4 expression was also evaluated. ALCL cases included 27 classical systemic forms and variants, 3 primary cutaneous (PC) forms, and 3 acquired immunodeficiency syndrome-associated forms. Cytotoxic antigen expression was also studied in 51 cases of Hodgkin's disease (HD) and 17 large B-cell lymphomas (LBCLs) with anaplastic cytomorphology and/or CD30 positivity. We found that 76% of ALCLs, representing all subtypes except the PC forms, expressed either TIA-1, perforin, or both proteins. Expression of TIA-1 and perforin were highly correlated (P < .001). On the basis of their immunophenotypic profiles, several subtypes of cytotoxic antigen positive and negative ALCL could be recognized. Fifty-five percent of ALCLs (18 of 33) displayed an immunophenotypic profile consistent with cytotoxic T cells. Six cases expressed cytotoxic granular proteins in the absence of lineage specific markers, and one case expressed both T-cell – and natural killer cell–like markers. These 7 cases (21%) were placed into a phenotypic category of cytotoxic lymphocytes of unspecified subtype. Twenty-four percent (8 cases) of ALCLs were cytotoxic granule protein negative. All but one of these displayed a T-cell phenotype. Cytotoxic granule protein expression did not correlate with the presence of the NPM-ALK fusion transcript. Only 10% of the 51 HD cases were found to be TIA-1+, and none expressed perforin. Cytotoxic antigen expression was absent in LBCL. The expression of cytotoxic granule proteins in the majority of ALCL implies a cytotoxic lymphocyte phenotype and suggests that most cases originate from lymphocytes with cytotoxic potential. Furthermore, the demonstration of cytotoxic cell related proteins may be a useful addition to the current panel of antibodies used to distinguish ALCL, HD, and anaplastic LBCL.