Comparison of two immunohistochemical staining protocols for ALK demonstrates non-inferiority of a 5A4 clone-based protocol versus an ALK01 clone-based protocol for the diagnosis of ALK + anaplastic large cell lymphoma.

Detection of ALK rearrangement and/or expression of the ALK protein is an essential component in the evaluation of many neoplasms. Variability has been reported in the ability of different antibody clones to detect ALK expression. The ALK01 clone is commonly used to detect ALK expression in ALK-positive anaplastic large cell lymphoma (ALK + ALCL). However, this clone has been shown to lack sensitivity when used for solid tumors. The aim of this study was to determine if our high-sensitivity 5A4-based immunohistochemistry protocol is non-inferior to our ALK01-based protocol for the detection of ALK expression in ALK + ALCL. To compare the two protocols, we stained tissue microarrays of 126 hematolymphoid neoplasms and an additional 21 primary cutaneous ALK-negative anaplastic large cell lymphomas with both protocols. All 28 ALK + ALCL samples that were positive for the ALK01 antibody were also positive for the 5A4 clone. Three cases on the tissue microarray that were negative with the ALK01 antibody were clearly positive with the 5A4 antibody. We subsequently stained whole tissue sections of these three cases with the ALK01 antibody and found that these three cases were indeed positive with the ALK01 protocol, suggesting that the absence of staining on the tissue microarray samples was due to a combination of sampling error as well as a dimmer signal with the ALK01 protocol. Our study demonstrates that our 5A4-based protocol is non-inferior to the ALK01 antibody for the diagnosis of ALK-positive anaplastic large cell lymphoma, thus allowing our laboratory to discontinue the use of the ALK01-based protocol.

Genetic Subtypes of Systemic Anaplastic Large Cell Lymphoma Show Distinct Differences in PD-L1 Expression and Regulatory and Cytotoxic T Cells in the Tumor Microenvironment.

Anaplastic large cell lymphomas (ALCL) encompass several subgroups that differ in their clinical presentation, genetic features, and prognosis. We characterized the genetic subgroups of 74 patients with ALCL and correlated programmed death ligand 1 (PD-L1) protein expression and compared the densities and ratios of FOXP3+ T regulatory cells and CD8+ tumor-infiltrating lymphocytes (TILs) in tumor cells and the immune microenvironment. The subgroups included anaplastic lymphoma kinase (ALK)-positive (ALK+) ALCL and ALK-negative (ALK-) ALCL and DUSP22-rearranged and nonrearranged ALK- ALCL. None of our cases represented the TP63-rearrangement ALK- ALCL subgroup. Our results showed that ALK+ ALCL had a higher expression of PD-L1 in the tumor cells, in contrast to ALK- ALCL, which expressed high PD-L1 in tumor-associated macrophages (TAMs). DUSP22-rearranged ALK- ALCL lacked PD-L1 expression in the tumor cells and instead expressed PD-L1 only in TAMs. There was a significant positive correlation of PD-L1 expression between tumor and TAMs in ALK+ ALCL with a negative correlation in ALK- ALCL. Systemic ALCL subgroups had similar densities of CD8+ tumor-infiltrating lymphocytes and FOXP3 T regulatory cells, but differences were observed in the ratio of CD8/FOXP3. Our results suggest that alterations in tumor microenvironment and immune responses exist among systemic ALCL subgroups and these features may account for different clinical behavior and prognosis.

FOXP3-positive T-cell lymphomas in non-HTLV1 carriers include ALK-negative anaplastic large cell lymphoma: expanding the spectrum of T-cell lymphomas with regulatory phenotype.

Forkhead box P3 (FOXP3) is a specific marker for regulatory T-cells (Tregs). We report 6 cases of T-cell lymphomas with Treg phenotype based on diffuse positivity for FOXP3 in tumor cells. The patients showed a median age of 56 years with a male predominance. Sites of disease included lymph nodes (4), skin (2), subcutaneous tissue (1) and bone marrow (1). All cases showed monomorphic large cells, some with Hodgkin-like or anaplastic cells. All cases expressed pan T-cell markers and lacked cytotoxic markers; one case showed diffuse PD1 staining. Only one case harbored human T-lymphotrophic virus (HTLV)-1 DNA within tumor cells and was classified as adult T-cell leukemia/lymphoma (ATLL). Among 5 HTLV1-negative cases, 3 were classified as peripheral T-cell lymphoma, not otherwise specified (PTCL, NOS) and 2 fulfilled criteria for ALK-negative anaplastic large cell lymphoma (ALCL) with diffuse and strong CD30 positivity. We concluded that Treg phenotype may be rarely seen in HTLV1-negative cases, such as PTCL, NOS and ALK-negative ALCL. Our findings expand the spectrum of T-cell lymphomas with regulatory phenotype and suggest that consideration should be given to HTLV1 DNA testing in the appropriate clinical setting to rule out ATLL.

The role of intratumoral lymphovascular density in distinguishing primary from secondary mucinous ovarian tumors.

OBJECTIVE: Ovarian mucinous metastases commonly present as the first sign of the disease and are capable of simulating primary tumors. Our aim was to investigate the role of intratumoral lymphatic vascular density together with other surgical-pathological features in distinguishing primary from secondary mucinous ovarian tumors. METHODS: A total of 124 cases of mucinous tumors in the ovary (63 primary and 61 metastatic) were compared according to their clinicopathological features and immunohistochemical profiles. The intratumoral lymphatic vascular density was quantified by counting the number of vessels stained by the D2-40 antibody. RESULTS: Metastases occurred in older patients and were associated with a higher proportion of tumors smaller than 10.0 cm; bilaterality; extensive necrosis; extraovarian extension; increased expression of cytokeratin 20, CDX2, CA19.9 and MUC2; and decreased expression of cytokeratin 7, CA125 and MUC5AC. The lymphatic vascular density was increased among primary tumors. However, after multivariate analysis, the best predictors of a secondary tumor were a size of 10.0 cm or less, bilaterality and cytokeratin 7 negativity. Lack of MUC2 expression was an important factor excluding metastasis. CONCLUSIONS: The higher intratumoral lymphatic vascular density in primary tumors when compared with secondary lesions suggests differences in the microenvironment. However, considering the differential diagnosis, the best discriminator of a secondary tumor is the combination of tumor size, laterality and the pattern of expression of cytokeratin 7 and MUC2.

The role of intratumoral lymphovascular density in distinguishing primary from secondary mucinous ovarian tumors

OBJECTIVE: Ovarian mucinous metastases commonly present as the first sign of the disease and are capable of simulating primary tumors. Our aim was to investigate the role of intratumoral lymphatic vascular density together with other surgical-pathological features in distinguishing primary from secondary mucinous ovarian tumors. METHODS: A total of 124 cases of mucinous tumors in the ovary (63 primary and 61 metastatic) were compared according to their clinicopathological features and immunohistochemical profiles. The intratumoral lymphatic vascular density was quantified by counting the number of vessels stained by the D2-40 antibody. RESULTS: Metastases occurred in older patients and were associated with a higher proportion of tumors smaller than 10.0 cm; bilaterality; extensive necrosis; extraovarian extension; increased expression of cytokeratin 20, CDX2, CA19.9 and MUC2; and decreased expression of cytokeratin 7, CA125 and MUC5AC. The lymphatic vascular density was increased among primary tumors. However, after multivariate analysis, the best predictors of a secondary tumor were a size of 10.0 cm or less, bilaterality and cytokeratin 7 negativity. Lack of MUC2 expression was an important factor excluding metastasis. CONCLUSIONS: The higher intratumoral lymphatic vascular density in primary tumors when compared with secondary lesions suggests differences in the microenvironment. However, considering the differential diagnosis, the best discriminator of a secondary tumor is the combination of tumor size, laterality and the pattern of expression of cytokeratin 7 and MUC2. .