Human T-lymphotropic virus type-1 related adult T-cell leukemia/lymphoma presenting as a parotid mass diagnosed by fine-needle aspiration biopsy

A 48-yr-old black woman with a history of blood transfusions for menorrhagia secondary to uterine fibroids but no known Caribbean association presented with a 6-wk history of a rapidly enlarging right parotid mass. At the time of presentation, she could not close her right eye. An aspiration biopsy showed small, medium, and large lymphoma cells with angulated nuclei, red macronucleoli, and basophilic cytoplasm with fine vacuoles. Flow cytometry indicated a (CD25(+)/CD7(-)) T-cell lineage, suggesting an human T-lymphotropic virus (HTLV) 1-related T-cell leukemia/lymphoma, which was confirmed by polymerase chain reaction (PCR)-based amplification on DNA extracted from fresh tissue with specific oligonucleotide primers for HTLV-1 DNA sequence. Histology showed interstitial infiltration and destruction of the parotid parenchyma by lymphoma cells without involvement of adjacent lymph nodes. Total body CT scan and magnetic resonance imaging (MRI) studies were negative for lymphadenopathy but showed liver metastasis. To our knowledge, this is the first reported case of HTLV-1-related primary parotid lymphoma as the initial presentation of adult T-cell leukemia/lymphoma.     

Cytological diagnosis of adult T‐cell leukemia/lymphoma in sputum

Adult T‐cell leukemia/lymphoma (ATLL) is a rare and often aggressive T‐cell leukemia/lymphoma that has been linked to infection by the human T‐cell lymphotropic virus type 1 (HTLV‐1). ATLL can involve multiple organs including the respiratory airway. A 53‐year‐old Trinidadian woman presented with productive cough and progressive shortness of breath. Her past medical history included duodenal strongyloidosis, skin rash, and hypercalcemia. Radiological studies showed increased interstitial markings. Sputum cytology showed atypical pleomorphic, small‐to‐medium‐sized, lobated lymphocytes with irregular and hyperchromatic nuclei resembling “flower cells” which were CD3±/CD20? by immunocytochemistry. A lung biopsy showed interstitial, peribronchiolar, and subpleural infiltration by a CD3±/CD25± atypical lymphocytic infiltrate. Together with peripheral blood findings and positive HTLV‐1 serology, the diagnosis of ATLL was made. We suggest that sputum evaluation in patients with ATLL risk factors can be diagnostic. Diagn. Cytopathol. 2016;44:416–418. © 2016 Wiley Periodicals, Inc.     

Quantitative PCR for HTLV‐1 provirus in adult T‐cell leukemia/lymphoma using paraffin tumor sections

Detection of HTLV‐1 provirus using paraffin tumor sections may assist the diagnosis of adult T‐cell leukemia/lymphoma (ATLL). For the detection, non‐quantitative PCR assay has been reported, but its usefulness and limitations remain unclear. To our knowledge, quantitative PCR assay using paraffin tumor sections has not been reported. Using paraffin sections from ATLLs and non‐ATLL T‐cell lymphomas, we first performed non‐quantitative PCR for HTLV‐1 provirus. Next, we determined tumor ratios and carried out quantitative PCR to obtain provirus copy numbers. The results were analyzed with a simple regression model and a novel criterion, cut‐off using 95 % rejection limits. Our quantitative PCR assay showed an excellent association between tumor ratios and the copy numbers (r = 0.89, P < 0.0001). The 95 % rejection limits provided a statistical basis for the range for the determination of HTLV‐1 involvement. Its application suggested that results of non‐quantitative PCR assay should be interpreted very carefully and that our quantitative PCR assay is useful to estimate the status of HTLV‐1 involvement in the tumor cases. In conclusion, our quantitative PCR assay using paraffin tumor sections may be useful for the screening of ATLL cases, especially in HTLV‐1 non‐endemic areas where easy access to serological testing for HTLV‐1 infection is limited.     

Development of ultra-super sensitive immunohistochemistry and its application to the etiological study of adult T-cell leukemia/lymphoma

Antigen retrieval (AR) and ultra-super sensitive immunohistochemistry (ultra-IHC) have been established for application to archival human pathology specimens. The original ultra-IHC was the ImmunoMax method or the catalyzed signal amplification system (ImmunoMax/CSA method), comprising the streptavidin-biotin complex (sABC) method and catalyzed reporter deposition (CARD) reaction with visualization of its deposition. By introducing procedures to diminish non-specific staining in the original ultra-IHC method, we developed the modified ImmunoMax/CSA method with AR heating sections in an AR solution (heating-AR). The heating-AR and modified ImmunoMax/CSA method visualized expression of the predominantly simple present form of HTLV-1 proviral DNA pX region p40Tax protein (Tax) in adult T-cell leukemia/lymphoma (ATLL) cells in archival pathology specimens in approximately 75% of cases. The simple present form of Tax detected exhibited a close relation with ATLL cell proliferation. We also established a new simplified CSA (nsCSA) system by replacing the sABC method with the secondary antibody- and horse radish peroxidase-labeled polymer reagent method, introducing the pretreatments blocking non-specific binding of secondary antibody reagent, and diminishing the diffusion of deposition in the CARD reaction. Combined with AR treating sections with proteinase K solution (enzymatic-AR), the nsCSA system visualized granular immunostaining of the complex present form of Tax in a small number of ATLL cells in most cases, presenting the possibility of etiological pathological diagnosis of ATLL and suggesting that the complex present form of Tax-positive ATLL cells were young cells derived from ATLL stem cells. The heating-AR and ultra-IHC detected physiological expression of the p53 protein and its probable phosphorylation by Tax in peripheral blood mononuclear cells of peripheral blood tissue specimens from HTLV-1 carriers, as well as physiological and pathological expression of the molecules involved with G1 phase progression and G1-S phase transition (E2F-1, E2F-4, DP-1, and cyclin E) in ATLL and peripheral T-cell lymphoma cells. The ultra-IHC with AR is useful for etiological pathological diagnosis of ATLL since HTLV-1 pathogenicity depends on that of Tax, and can be a useful tool for studies translating advanced molecular biology and pathology to human pathology.     

Angioimmunoblastic T-cell lymphoma with hyperplastic germinal centers: a clinicopathological and immunohistochemical study of 10 cases

An absence of germinal centers is one of the histological characteristics of angioimmunoblastic T-cell lymphoma (AITL). We report here 10 unusual cases of AITL with hyperplastic germinal centers. The clinical presentation of each patient was characterized by generalized lymphadenopathy, constitutional symptoms and polyclonal hypergammaglobulinemia. The initial biopsy findings of each patient were similar and were characterized by hyperplastic germinal centers with ill-defined borders and a proliferation of high endothelial venules (HEV). In the paracortical area there was a mixed infiltrate including irregularly shaped clusters or small nests of clear cells in all cases. Moreover, the clear cells invaded the lymphoid follicles, resulting in expansion of the germinal centers, except for one case. Immunohistochemistry revealed that the tumor cells, including clear cells, were CD4-expressing T cells. Some of the atypical lymphocytes were also Bcl-6-positive. A majority of the follicular dendritic cell networks showed a normal/reactive or an expanded/disrupted pattern in all cases. Moreover, three lesions possessed a few large irregularly shaped proliferations of follicular dendritic cells around the HEV Four cases progressed to AITL within a few years. The present 10 cases probably represent an early stage of AITL preceding follicular dendritic cell hyperplasia. Detection of clear cells, Bcl-6-positive atypical T lymphocytes, and foci of irregularly shaped proliferation of follicular dendritic cells appears to be critical for early diagnosis and treatment of AITL with hyperplastic follicles.     

结外鼻型NK/T细胞淋巴瘤28例临床病理分析

目的：探讨结外鼻型NK/T细胞淋巴瘤( extranodal natural killer/T-cell lymphoma, nasal type, EN-NK/TCL)的临床病理学特征、诊断及鉴别诊断。方法应用免疫组化、EBER原位杂交技术检测28例EN-NK/TCL,依据WHO(2008)淋巴造血组织肿瘤分类进行临床病理学分析。结果28例EN-NK/TCL中,男性13例,女性15例,男女之比为1∶1．2,平均年龄46岁,中位年龄44．5岁。18例发生于鼻腔,5例发生于皮肤,扁桃体、上腭、舌根、肾上腺、胃各1例。临床主要表现为鼻塞,皮肤病变可表现为皮疹、溃疡、斑块或结节形肿物。可伴有B症状、淋巴结肿大,可累及多个部位。肿瘤细胞为小、中、大淋巴细胞或呈混合型,常见血管中心性或血管破坏的生长方式及坏死,多伴有炎细胞浸润。免疫表型：T细胞标志物( CD3ε最敏感)、CD56及细胞毒性标志物均阳性,原位杂交EBER呈阳性。10例获得随访,其中1例死亡。结论 EN-NK/TCL好发于上呼吸道,其次是皮肤。结合形态学、免疫表型及EBER原位杂交结果可确诊。     

Composite T lymphoblastic leukemia/lymphoma and diffuse large B-cell lymphoma: case report

This report concerns a unique case of a composite lymphoma composed of T-lymphoblastic leukemia/lymphoma (T-LBL) and diffuse large B-cell lymphoma (DLBCL) in a 72-year-old woman with generalized lymphadenopathy, splenomegaly and ascites. Laboratory findings showed increased lactate dehydrogenase and soluble interleukin-2 receptor. The biopsy specimen showed replacement of the normal architecture of the lymph nodes by a tumor containing a dual cell population composed of large lymphocytes and medium-sized lymphocytes. Sheets of large lymphocytes often were punctuated by clusters of medium-sized lymphocytes. Flow cytometry and immunohistochemical analysis showed a composite lymphoma with both T-LBL and DLBCL. The T-LBL expressed CD1a, CD3, CD4, CD8, and terminal deoxynucleotidyl transferase. The DLBCL expressed CD19 and CD20, CD23, bcl-2, bcl-6, MUM1 and immunoglobulin κ light chain. Polymerase chain reaction detected a monoclonal pattern of T-cell receptor γ and immunoglobulin heavy chain rearrangements in the same specimen. She received eight cycles of R-CHOP (rituximab+cyclophosphamide, doxorubicin, vincristine, prednisone) therapy and achieved complete remission. She has shown no signs of recurrence 20 months after the diagnosis. We describe here a very unusual and, to the best of our knowledge, an as yet never reported case of a primary composite lymphoma of T-LBL and DLBCL.     

Adult T cell leukemia/lymphoma with massive involvement of cardiac muscle and valves

An autopsy case of a 58-year-old woman with massive cardiac Involvement of adult T cell leukemia/lymphoma (ATLL) is reported. She developed cardiac failure due to aortic and mitral regurgitation with cardiac infiltration of ATLL cells, and underwent replacement of both aortic and mitral valves. Studies of the cut-surfaces revealed diffuse thickening of the subendocardial wall of the left chamber with widespread whitish-brown tumor infiltrates. In the regions surrounding the replaced aortic and mitral valves there was also massive tumor cell infiltration. The tumor cells infiltrating the cardiac muscle wall were T cell in origin and exhibited Leu-3a (CD4)-positive immunoreaction. Ultrastructurally, tumor cells contained markedly indented nuclei and some were attached directly to the muscle cells. These findings suggest that this was an unusual form of ATLL with widespread involvement of the heart.     

CD4 and CD8 double‐negative adult T‐cell leukemia/lymphoma with monomorphic cells expressing CD99: A diagnostic challenge in a country non‐endemic for human T‐cell leukemia virus

Adult T‐cell leukemia/lymphoma (ATLL) is a peripheral T‐cell neoplasm caused by human T‐cell lymphotropic virus type I (HTLV‐I). The neoplastic cells are highly pleomorphic and are usually CD4+ and CD8? phenotypically. We reported the case of a 46‐year‐old woman presenting with fever, abdominal distention, lymphadenopathy, leukocytosis and hypercalcemia. Nodal biopsy showed diffuse infiltration by monomorphic small to medium‐sized atypical lymphocytes expressing CD3, CD25, CD30 and CD99, but not CD1a, CD4, CD8, CD34, terminal deoxynucleotidyl transferase or ALK. An initial diagnosis of T‐lymphoblastic leukemia/lymphoma was made based on cytomorphology, CD4 and CD8 double negativity, and the expression of CD99. The diagnosis was later revised to ATLL based on the positive serology study for anti‐HTLV I/II antibody and confirmation by the clonal integration of HTLV‐I proviral DNA into the tumor tissues by Southern blotting analysis. The patient had a stage IVB disease and died of septic shock after 2 courses of chemotherapy 3 months after diagnosis. Immunohistochemical staining for CD99 in archival ATLL tissues showed a positive rate of 67% (4 of 6 tumors). Our case showed that ATLL with atypical morphology and immunophenotype in HTLV non‐endemic areas might pose a diagnostic challenge and CD99 expression is frequent in ATLL.     

Monoclonal antibody HML-1 reactivity with adult T-cell leukaemia/lymphoma and other lymphomas

Human T-cell leukaemia/lymphoma virus type 1 (HTLV-1), a causative virus of adult T-cell leukaemia/lymphoma (ATLL), is known to be transmitted by breast-feeding. Using a monoclonal antibody HML-1 which labels human intestinal intra-epithelial T lymphocytes, we have immunohistochemically examined ATLL tissues in order to evaluate the possibility that HTLV-1 infected intestinal T cells are the origin of ATLL cells. Previously this antibody was reported to react with intestinal T-cell malignant lymphomas but not with peripheral tumours, or any B-cell lymphomas. We investigated 181 patients with malignant lymphomas and found that 19 out of 113 ATLLs were positive for HML-1. T-cell malignant lymphomas excluding ATLL also reacted with HML-1 (7/24), but all the B-cell lymphomas 0/33) and non-neoplastic lymph node and skin lesions (0/10) were negative for HML-1. In patients with ATLL and other T-cell malignant lymphomas, the positivity level of HML-1 was relatively higher in stomach (3/7) and tonsil (2/6) than that in lymph nodes (15/100) and skin (8/47). We observed one HML-1 positive ATLL patient with tumour formation in the skin and lymphadenopathy and marked infiltration of the large intestine but minimal involvement of other organs. Although HML-1 was frequently expressed in gastric infiltration of ATLL, the level of positivity was too low in lymph nodes to support the hypothesis that HTLV-1 infected intestinal T cells are the origin of ATLL cells. Some of the HML-1 positive ATLL cases co-expressed CD30. Furthermore, three of six cases of Ki-1 lymphoma (large anaplastic cell lymphoma) were positive for HML-1. We conclude that expression of HML-1 in ATLL reflects an activated state of the lymphoma cells, but not the intestinal origin of ATLL cells.     

CD30 (Ki-1) expression in adult T-cell leukaemia/lymphoma is associated with distinctive immunohistological and clinical characteristics

Twenty-one patients with CD30 (Ki-1) positive lymphoma were studied from a group of 91 patients with adult T-cell leukaemia/lymphoma. The patients were grouped into three types: diffuse CD30 positive anaplastic large cell lymphoma in 11 patients (group 1); pleomorphic type lymphoma with diffuse CD30 expression in five patients (group 2); and pleomorphic type lymphoma with positive CD30 expression in large cells but negative in medium-sized and small cells in five patients (group 3). The patients with diffuse CD30 positive lymphomas (groups 1, 2) frequently presented with extranodal tumours (68.8%) and lymph node enlargement greater than 2 cm in diameter (50%), and rarely with leukaemic changes, bone marrow involvement and hypercalcaemia (one case of each). Patients in group 3 rarely had extranodal tumours, but had frequent leukaemic changes. Expression of intercellular adhesion molecule (ICAM-1; CD54) by the lymphoma cells in 13 patients (81.3%) with diffuse CD30 positive lymphomas, was significantly higher than that in 33 patients (9.1%) with CD30 negative adult T-cell leukaemia/lymphomas. No positive reaction for epithelial membrane antigen (EMA) was found in the lymphoma cells of CD30 positive cases. The overall survival in patients with diffuse CD30 positive lymphomas was better than that of CD30 negative adult T-cell leukaemia/lymphoma patients, but showed no significant difference. These findings suggest that diffuse CD30 positive adult T-cell leukaemia/lymphoma has unusual clinical and immunohistological findings. It is also speculated that local tumour formation and leukaemic changes in such diffuse CD30 positive cases are influenced by CD54 (ICAM-1) expression by the lymphoma cells.     

Acute viral lymphadenitis mimicking low-grade peripheral T-cell lymphoma. A clinicopathological study of nine cases

Acute viral lymphadenitis, especially infectious mononucleosis (IM), often shows the presence of Reed-Sternberg-like cells, resulting in confusion with Hodgkin's disease. However, acute viral lymphadenitis requiring differential diagnosis from non-Hodgkin's lymphoma is not widely recognized. We describe the clinicopathological and immunohistochemical features of lymph node lesions from nine such patients which pose serious problems of differential diagnosis from low-grade peripheral T-cell lymphoma. There were three males and six females with ages ranging from 21 to 44 years (median 25 years). All patients had "B" symptoms and multicentric lymphadenopathy. The clinical course was also self-limiting. Each lymph node specimen showed an obvious expansion of an interfollicular area by pleomorphic and polymorphous infiltration with an increased number of arborizing postcapillary venules. The infiltrate was composed of variable numbers of small and medium-sized lymphocytes, immunoblasts, plasma cells in various stage of maturation and occasional granulocytes. The small lymphocytes usually had regular round nuclei, whereas the medium-sized lymphocytes occasionally showed nuclear pleomorphism. Hyperreactivity of B-lymphocytes, including hyperplastic germinal centers and/or foci of monocytoid B-cells, was seen in parts of the lesion. The majority of the interfollicular T-lymphocytes, including T-immunoblasts, expressed CD8 antigen. Various numbers of TIA-1-positive small and medium-sized T-cells were observed in the paracortical area. Despite these findings, the overall histological picture of this series posed serious difficulties when differentially diagnosing this condition from low-grade peripheral T-cell lymphomas such as angioimmunoblastic T-cell (AILD) and T-zone types, indicating that viral lymphadenitis occasionally presents with histological features of AILD and T-zone lymphomas. To avoid overdiagnosis and overtreatment, we emphasize the need to pay careful attention to the clinical and laboratory findings as well as the morphological features.     

Fine-needle aspiration cytology of extranodal natural killer/T-cell lymphoma

Extranodal NK/T-cell lymphoma, nasal type, is a predominantly extranodal lymphoma characterized histologically by prominent necrosis, angiocentric growth, and vascular destruction. Only one report describing its fine-needle aspiration (FNA) cytologic features is available and shows highly unusual findings for a lymphoma. The present case concerns a 58-yr-old patient that presented with a soft tissue mass of the thigh in addition to an ulcerative lesion of the palate and nodular hepatic and splenic lesions. FNA cytology of the thigh tumor was interpreted as a malignant mesenchymal lesion (sarcoma). The subsequent pathologic study revealed an NK/T-cell lymphoma. Our findings are very similar to those previously reported. They were highly unusual for a lymphoma and consisted of polymorphic, round to spindle neoplastic cells distributed in irregular aggregates, and single cells. No significant number of lymphoglandular bodies were present.     

A case of post-mogamulizumab relapse of acute-type adult T-cell leukemia/lymphoma successfully treated with mogamulizumab and etoposide

A 70-year-old man presented to us with the chief complaints of a generalized rash and a mass in the right clavicular region that he first noticed in the year 2012. Biopsy of the mass led to the diagnosis of cutaneous nodular mass-type adult T-cell leukemia/lymphoma (ATLL) in March 2013. Phototherapy was started, and the symptoms improved temporarily. However, in late June 2013, the serum lactate dehydrogenase (LDH) level increased to 358 IU/L, which was 1.6 times higher than the upper limit of the reference range; based on the findings, transformation of the disease to the acute type was diagnosed. The patient was treated with 6 courses of CHOP therapy (cyclophosphamide, doxorubicin, vincristine, and prednisolone), which resulted in complete remission (CR). However, the rash recurred in late October 2013, and treatment with mogamulizumab was initiated. A total of 8 courses of mogamulizumab were administered, which resulted in CR. The rash and cutaneous nodular masses recurred again in January 2014, and a total of 8 courses of mogamulizumab were administered again starting in February 2014. However, the patient’s symptoms began to worsen gradually. Phototherapy was also initiated, but had to be discontinued due to the development of photosensitivity. Treatment with the combination of mogamulizumab and etoposide (25 mg/day for 21 days) was started in May 2014. The nodular mass rapidly decreased in size. The rash or cutaneous nodular mass had not recurred as of August 2014. Thus, combined therapy with mogamulizumab plus etoposide is considered to be effective for resolution of the cutaneous nodular masses in patients with ATLL.     

Expression of transmembrane adaptor protein PAG/Cbp in diffuse large B-cell lymphoma: immunohistochemical study of 73 cases

PAG/Cbp is a transmembrane adaptor protein involved in proximal immune signaling. It is expressed in reactive germinal centers (GC) of secondary lymphatic follicles and related malignant lymphomas. We studied PAG/Cbp expression in GC-like and non-GC-like diffuse large B-cell lymphoma (DLBCL) subtypes. Seventy-three cases of DLBCL identified among 155 malignant lymphomas were classified as GC-like DLBCL (CD10+ or CD10-, bcl-6+, and MUM1-) and non-GC-like DLBCL (CD10-, MUM1+ or CD10-, bcl-6+, MUM1+). PAG/Cbp was detected by monoclonal antibody MEM-255 following routine immunohistochemical procedures. Thirty-five of 40 GC-like DLBCLs (88%) and 20 of 33 non-GC-like DLBCL cases (61%) expressed PAG/Cbp. Four of 12 bcl-6-negative non-GC-like DLBCL cases (33%) were PAG/Cbp positive, and only 4 of 20 bcl-6-positive non-GC-like DLBCL cases (25%) were PAG/CBP negative. All 37 FL and all 5 Burkitt's lymphomas (BL) expressed PAG/Cbp, whereas all 6 mantle cell lymphomas (MCL) and 4 of 5 chronic lymphocytic leukemias (CLL/SLL) were PAG/Cbp negative. PAG/Cbp is a reliable GC marker. Its expression correlates with GC-like DLBC phenotype in a significant majority of cases. It is typically absent in MCL and SLL/CLL.     

Clinical and histopathological significance of PD-1 expression in cutaneous lesions of adult T-cell leukemia–lymphoma

Background

Adult T-cell leukemia–lymphoma (ATL) is a mature T-cell malignancy caused by human T-cell leukemia virus type I infection and is known to exhibit cutaneous involvement in 50% or more patients. Few studies have evaluated the clinicopathological significance of programmed death-1 (PD-1) expression in the cutaneous lesions of ATL.

Adult T-cell leukemia/lymphoma in Jujuy,north-west Argentina

Human T-cell leukemia virus type 1 (HTLV-1) infection is prevalent in native Americans living in the Andes. Some of their malignant lymphomas (ML) show a peculiar histology suggestive of adult T-cell leukemia/lymphoma (ATLL). To determine whether ML resembling ATLL are indeed ATLL, re-analysis of 34 cases occurring in Jujuy, a province of Argentina, was conducted, concentrating on immunological phenotype, integration of HTLV-1 proviral DNA, expression of HTLV-1 p40Tax and p27Rex, and infection of Epstein-Barr virus (EBV). The ML were 22 cases of mature peripheral T-cell and natural killer (NK)-cell neoplasm (mT/NKN), 11 B-cell malignant neoplasms and one Hodgkin's lymphoma. Polymerase chain reaction against the HTLV-1 proviral DNA, using DNA extracted from paraffin sections, indicated integration of the HTLV-1 proviral DNA in three cases of eight mT/NKN. Two other cases of mT/NKN were positive for anti-HTLV-1 antibodies. Expression of p40Tax and p27Rex was detected in all five of these mT/NKN cases associated with HTLV-1. As such, these five mT/NKN were rediagnosed as ATLL. In situ hybridization signals for EBV-encoded small nuclear early region-1 were detected in nine cases of mT/NKN, of which five cases of NK-cell lymphoma were found to have cytoplasmic CD3 expression, a CD56 phenotype and positivity of TIA1. According to the new World Health Organization classification, the mT/NKN class includes five cases of ATLL and five cases of NK-cell lymphomas. The five cases of ATLL were of native American extraction from an HTLV-1-endemic area around Jujuy, north-west Argentina.     

Adult T-cell leukemia/lymphoma accompanying follicular mucinosis: a case report with review of the literature

Follicular mucinosis is recognized as one of the histopathological reaction patterns characterized by the accumulation of mucin within follicular epithelium. It is induced by various causes including inflammatory diseases, and more than half of the cases are associated with malignant lymphoma, mainly mycosis fungoides. Herein, we describe the third documented case of adult T-cell leukemia/lymphoma (ATLL) accompanying follicular mucinosis. A 72-year-old Japanese male presented with persistent erythema in his arm and neck. Laboratory tests demonstrated positivity for human T-cell leukemia virus (HTLV)-1 antibodies. Histopathological study of the biopsy specimen from the neck revealed superficial perivascular, nodular, and intrafollicular lymphocytic infiltrations. These lymphocytes were small- to medium-sized and had convoluted nuclei. Mucoid material deposition was observed within the hair follicles, and it was digested by hyaluronidase. Immunohistochemically, these lymphocytes were positive for CD3, CD4, CD25, and Foxp3. Accordingly, an ultimate diagnosis of ATLL accompanying follicular mucinosis was made. The skin is the most common extralymphatic site of involvement of ATLL. The present case clearly demonstrated that albeit extremely rare, ATLL can cause follicular mucinosis. Therefore, ATLL should be included in the differential diagnostic consideration of follicular mucinosis.