[Adult T-cell leukemia/lymphoma diagnosed by RNA in situ hybridization for HTLV-1 bZIP factor].

A 62-year-old man visited the Department of Otorhinolaryngology at our hospital with a chief complaint of a pharyngeal mass. He was admitted to our department with a diagnosis of T-cell lymphoma based on a biopsy of a mesopharyngeal tumor. Although clonality analysis was not performed due to the lack of an appropriate sample, we considered the possibility of lymphoma-type (Lugano classification stage II) adult T-cell leukemia-lymphoma (ATL), as the anti-HTLV-1 antibody was positive. During the course of the disease, the peripheral blood smear revealed atypical lymphocytes with cleaved nuclei, and inverse PCR was performed with DNA extracted from those cells; however, the result showed that the pattern of HTLV-1 proviral DNA integration sites was polyclonal. Further, we performed RNA in situ hybridization targeting HTLV-1 bZIP factor (HBZ-ISH) using the formalin-fixed paraffin-embedded (FFPE) tissue samples of the mesopharyngeal tumor, and a high expression of HBZ was found in the tumor cells, leading to the diagnosis of ATL. These findings suggest the effectiveness of the novel diagnostic method using FFPE tissue samples for ATL.

A new diagnostic algorithm using biopsy specimens in adult T-cell leukemia/lymphoma: combination of RNA in situ hybridization and quantitative PCR for HTLV-1.

Histopathological distinction between adult T-cell leukemia/lymphoma (ATLL) and other T-cell neoplasms is often challenging. The current gold standard for the accurate diagnosis of ATLL is the Southern blot hybridization (SBH) assay, which detects clonal integration of human T-cell leukemia virus type I (HTLV-1) provirus. However, SBH cannot be performed with small biopsy or formalin-fixed paraffin-embedded (FFPE) tissue samples because this assay requires a large amount of DNA without degradation. Here we developed a new diagnostic algorithm for the accurate diagnosis of ATLL using FFPE samples. This method combines two HTLV-1 detection assays, namely, ultrasensitive RNA in situ hybridization using RNAscope for HTLV-1 bZIP factor (HBZ-RNAscope), and quantitative PCR targeting the tax gene (tax-qPCR). We analyzed 119 FFPE tissue specimens (62 ATLL, and 57 non-ATLL, including 41 HTLV-1 carriers) and compared them with the SBH results using the corresponding fresh-frozen samples. As a result, tax-qPCR had a higher ATLL identification rate than HBZ-RNAscope (88% [52/59], and 63% [39/62], respectively). However, HBZ-RNAscope clearly visualized the localization of HTLV-1-infected tumor cells and its identification rate increased to 94% (17/18) when the analysis was limited to samples up to 2 years old, indicating its usefulness in the daily diagnosis. The diagnostic algorithm combining these two assays successfully evaluated 94% (112/119) of samples and distinguished ATLL from non-ATLL cases including HTLV-1 carriers with 100% sensitivity and specificity. This method is expected to replace SBH and increase the accuracy of the diagnosis of ATLL.

Dermatopathic reaction of lymph nodes in HTLV-1 carriers: a spectrum of reactive and neoplastic lesions.

AIMS: Dermatopathic reaction is a histopathological finding of lymph nodes that usually occurs in patients with inflammatory pruritic cutaneous lesions. However, it is sometimes seen in patients with cutaneous T cell lymphoma. Adult T cell leukaemia/lymphoma (ATLL) is a T cell malignancy caused by infection with human T cell leukaemia virus type I (HTLV-1), which is frequently accompanied by cutaneous lesions. However, the detailed clinicopathological characteristics of the dermatopathic reaction of lymph nodes in ATLL patients and HTLV-1 carriers, addressed in this study, remains to be clarified. METHODS AND RESULTS: We retrospectively analysed 18 nodal lesions with dermatopathic reaction in HTLV-1 carriers. Axillary and inguinal lymph nodes were the primary affected tissues. Three cases with atypical lymphoid cell infiltration were defined as ATLL with dermatopathic reaction (ATLL-D), showing an abnormal T cell immunophenotype and T cell monoclonality. Two of the three ATLL-D patients died 14 and 7 months after diagnosis (the third case had a very short follow-up). The other 15 patients were indistinguishable from reactive lesions and were defined as HTLV-1-associated lymphadenitis with dermatopathic reaction (HAL-D). They showed an indolent clinical course, with only one case eventually transforming to aggressive disease. CONCLUSIONS: Lymph node lesions accompanied by dermatopathic reaction in HTLV1 carriers represent a spectrum that includes reactive and neoplastic conditions. HAL-D should be distinguished from ATLL-D, especially to avoid overtreatment.

Co-occurrence of EBV-positive classic Hodgkin lymphoma and B-cell lymphomas of different clonal origins: A case report and literature review.

Although cases with metachronous or synchronous co-occurrence of classic Hodgkin lymphoma (CHL) and B-cell non-Hodgkin lymphoma (B-NHL) have been reported, few reports have analyzed the clonal relationship between both lesions in detail, especially in Epstein-Barr virus (EBV)-positive settings. Here, we report a case of a 38-year-old male with CHL, followed by the recurrence of EBV-positive mucocutaneous ulcers of the large intestine and EBV-positive diffuse large B-cell lymphoma in the liver. Surprisingly, polymerase chain reaction analysis for immunoglobulin heavy chain gene rearrangement revealed that all lesions were clonally distinct. We further reviewed the literature on synchronous and metachronous co-occurrence of CHL and B-NHL in EBV-positive settings. In contrast to EBV-negative settings, all evaluable cases showed clonally distinct multiple lesions. These findings suggest that histologically and clonally distinct B-cells could simultaneously proliferate in EBV-associated settings, providing a new insight into the pathogenesis of EBV-associated lymphoproliferative disorders.

Acute type adult T-cell leukemia cells proliferate in the lymph nodes rather than in peripheral blood.

A massive increase in the number of mature CD4+ T-cells in peripheral blood (PB) is a defining characteristic of acute type of adult T-cell leukemia (ATL). To date, the site of proliferation of ATL cells in the body has been unclear. In an attempt to address this question, we examined the expression of the proliferation marker, Ki-67, in freshly isolated ATL cells from PB and lymph nodes (LNs) of patients with various types of ATL. Our findings reveal that LN-ATL cells display higher expression of the Ki-67 antigen than PB-ATL cells in acute type patients. The gene expression of T-cell quiescence regulators such as Krüppel-like factor 2/6 and forkhead box protein 1 was substantially high in acute type PB-ATL cells. The expression of human telomerase reverse transcriptase, which is involved in T-cell expansion, was significantly low in PB-ATL cells from acute type patients, similar to that in normal resting T-cells. These findings suggest that ATL cells proliferate in the LNs rather than in PB.

Clinicopathological features of adult T-cell leukemia/lymphoma with HTLV-1-infected Hodgkin and Reed-Sternberg-like cells.

Hodgkin and Reed-Sternberg (HRS) cells, a hallmark of classic Hodgkin lymphoma (CHL), are occasionally detected in non-Hodgkin lymphomas, including adult T-cell leukemia/lymphoma (ATLL), a lymphoid neoplasm caused by human T-cell leukemia virus type 1 (HTLV-1). HRS-like cells associated with ATLL have been described to be of B-cell lineage and infected with Epstein-Barr virus (EBV), not HTLV-1. We herein describe clinicopathological findings in 8 cases (4 males and 4 females; median age, 73 years [range, 55-81 years]) of ATLL with HTLV-1-infected HRS-like cells identified by ultrasensitive RNA in situ hybridization for HTLV-1 basic leucine zipper factor (HBZ-ISH), a specific viral transcript of HTLV-1. All patients showed nodal or mediastinal lesions, and 5 of the 8 patients were at an advanced disease stage. HRS-like cells were positive for CD30, CD15, MUM1, CD25, and HBZ-ISH and negative for B-cell markers, including PAX5, pan-T-cell antigens, and EBV in all cases. Five cases were positive for CD4, and 6 cases were positive for fascin. HBZ was identified in both HRS-like cells and surrounding lymphoid cells in 1 case with an aggressive clinical course and only HRS-like cells in 7 cases, most of whom showed a clinical response regardless of the chemotherapeutic regimen. Even though the definitive lineage typing of the HTLV-1-infected HRS cells is one of the limitations of this study in the absence of single-cell microdissection for polymerase chain reaction analysis, the combination of diffuse HBZ-ISH positivity and negativity for PAX5 and EBV deemed these cases distinct from CHL arising in HTLV-1 carriers.