A US Multicenter Collaborative Study on Outcomes of Hematopoietic Cell Transplantation in Hepatosplenic T-Cell Lymphoma.

Hepatosplenic T-cell lymphoma (HSTCL) is a rare and aggressive type of peripheral T-cell lymphoma with median overall survival (OS) of approximately 1 year. Data on the effectiveness of hematopoietic cell transplantation (HCT) is limited, as is the choice between autologous HCT (auto-HCT) and allogeneic HCT (allo-HCT) in the treatment of this disease. To evaluate the outcome of patients with HSTCL who underwent either auto-HCT or allo-HCT, we performed a multi-institutional retrospective cohort study to assess outcomes of HCT in HSTCL patients. Fifty-three patients with HSTCL were included in the study. Thirty-six patients received an allo-HCT and 17 received an auto-HCT. Thirty-five (66%) were males. Median age at diagnosis was 38 (range 2 to 64) years. Median follow-up for survivors was 75 months (range 8 to 204). The median number of prior lines of therapy was 1 (range 1 to 4). Median OS and progression-free survival (PFS) for the entire cohort were 78.5 months (95% CI: 25 to 79) and 54 months (95% CI: 18 to 75), respectively. There were no significant differences in OS (HR: 0.63, 95% CI: 0.28 to 1.45, P = .245) or PFS (HR: 0.7, 95% CI: 0.32 to 1.57, P = .365) between the allo-HCT and auto-HCT groups, respectively. In the allo-HCT group, the 3-year cumulative incidence of relapse was 35% (95% CI: 21 to 57), while 3-year cumulative incidence of NRM was 16% (95% CI: 7 to 35). In the auto-HCT group, the 3-year cumulative incidence of relapse and NRM were 43% (95% CI: 23 to 78) and 14% (95% CI: 4 to 52), respectively. Both Auto-HCT and Allo-HCT are effective consolidative strategies in patients with HSTCL, and patients should be promptly referred for HCT evaluation.

Allogeneic hematopoietic stem cell transplantation after mogamulizumab in T-cell lymphoma patients: a retrospective analysis.

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is an important therapy for patients with T-cell lymphomas, including cutaneous T-cell lymphoma (CTCL), adult T-cell lymphoma (ATL), and peripheral T-cell lymphoma (PTCL). Mogamulizumab is an anti-CCR4 antibody that has been associated with an increased risk of transplant-related complications in retrospective analyses of ATL, particularly when administered within 50 days before transplantation. This post hoc analysis of 3 clinical trials examined safety and outcome data for 32 patients with CTCL (n = 23), ATL (n = 7), or PTCL (n = 2) who underwent allo-HSCT after mogamulizumab treatment. Overall, 22 patients (69%) were known to have graft-versus-host disease (GVHD), 8 patients (25%) did not report GVHD, and 2 patients (6%) had unknown GVHD status. Fourteen patients with known GVHD underwent transplantation between 50 and 365 days after their last dose of mogamulizumab, while 2 underwent transplantation within 50 days after treatment. Based on this limited evidence, GVHD was not associated with the time interval from last mogamulizumab dose to transplantation.

Update on T-Cell Lymphoma Epidemiology.

PURPOSE OF REVIEW: T-cell lymphomas (TCLs) are a group of rare subtypes of non-Hodgkin lymphoma derived from mature T-lymphocytes. Recent updates in lymphoma classification based on the cell-of-origin pathogenesis have shed new light on TCL epidemiology and outcomes. Contemporary regional consortia and international studies, including those conducted recently in Asia and South America, have provided an updated delineation of the major subtypes across various global regions. RECENT FINDINGS: Peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS), remains the most common subtype globally except in Asia, where extra-nodal NK-T cell lymphoma (ENKTL) has emerged as the most prevalent. Angioimmunoblastic T-cell lymphoma (AITL) is the second most common subtype globally except in South America where its incidence falls behind adult T-cell leukemia/lymphoma (ATLL) and ENKTL. ALK-negative anaplastic large cell lymphoma (ALCL) has been recognized as the second most common subtype in some parts of South America. Studies on the newly classified breast implant-associated ALCL (BIA-ALCL) are beginning to reveal its distribution and risk factors. Deciphering the epidemiology of TCLs is a challenging endeavor due to the rarity of these entities and ongoing refinement in classification. Collaborative efforts on prospective registries based on the most current WHO classifications will help capture the true epidemiology of TCL subtypes to better focus resources for diagnostic, prognostic, and therapeutic efforts.

[Successful cord blood transplantation for refractory gamma-delta hepatosplenic T-cell lymphoma developed during treatment of Crohn's disease].

The patient was a 21-year-old man who had been diagnosed with Crohn's disease and received infliximab and azathioprine six years earlier. He was admitted with fever and fatigue. Peripheral blood examination showed LDH 2,473 U/l and thrombocytopenia, and contrast-enhanced computed tomography (CT) showed hepatosplenomegaly. Bone marrow biopsy and liver biopsy showed CD4+CD56+TCRγδ＋CD8- atypical cells, leading to a diagnosis of hepatosplenic T-cell lymphoma (HSTCL). The patient was refractory to CHOP and DA-EPOCH, and therefore received cord blood transplantation with myeloablative conditioning. CT showed reduced in hepatosplenomegaly and peripheral blood examination showed LDH 165 U/l and plt 180,000/µl, so the patient was discharged on day117. HSTCL is a tumor of immature γδT cells with a Vδ1 mutation in the spleen, and immunodeficiency has been implicated in its pathogenesis. Patients with inflammatory bowel disease treated with azathioprine are known to have an increased risk of lymphoproliferative disease. In this case, use of immunosuppressive drugs for Crohn's disease may have caused malignant transformation of γδ cells in the intestinal epithelium. Although the patient was refractory to chemotherapy, he was able to achieve remission with early cord blood transplantation and long-term survival is expected.

KLRG1 Cell Depletion as a Novel Therapeutic Strategy in Patients with Mature T-Cell Lymphoma Subtypes.

PURPOSE: Develop a novel therapeutic strategy for patients with subtypes of mature T-cell and NK-cell neoplasms. EXPERIMENTAL DESIGN: Primary specimens, cell lines, patient-derived xenograft models, commercially available, and proprietary anti-KLRG1 antibodies were used for screening, target, and functional validation. RESULTS: Here we demonstrate that surface KLRG1 is highly expressed on tumor cells in subsets of patients with extranodal NK/T-cell lymphoma (ENKTCL), T-prolymphocytic leukemia (T-PLL), and gamma/delta T-cell lymphoma (G/D TCL). The majority of the CD8+/CD57+ or CD3-/CD56+ leukemic cells derived from patients with T- and NK-large granular lymphocytic leukemia (T-LGLL and NK-LGLL), respectively, expressed surface KLRG1. The humanized afucosylated anti-KLRG1 monoclonal antibody (mAb208) optimized for mouse in vivo use depleted KLRG1+ TCL cells by mechanisms of ADCC, ADCP, and CDC rather than apoptosis. mAb208 induced ADCC and ADCP of T-LGLL patient-derived CD8+/CD57+ cells ex vivo. mAb208 effected ADCC of subsets of healthy donor-derived KLRG1+ NK, CD4+, CD8+ Tem, and TemRA cells while sparing KLRG1- naïve and CD8+ Tcm cells. Treatment of cell line and TCL patient-derived xenografts with mAb208 or anti-CD47 mAb alone and in combination with the PI3K-δ/γ inhibitor duvelisib extended survival. The depletion of macrophages in vivo antagonized mAb208 efficacy. CONCLUSIONS: Our findings suggest the potential benefit of a broader treatment strategy combining therapeutic antibodies with PI3Ki for the treatment of patients with mature T-cell and NK-cell neoplasms. See related commentary by Varma and Diefenbach, p. 2300.

Hepatosplenic T-cell lymphoma and inflammatory bowel disease.

A 48-year-old man with a diagnosis of ulcerative colitis 18 years ago, under immunosuppressive treatment with azathioprine in the last 6 years due to corticosteroid dependence, was admitted to the Emergency Department due to fever of one week's evolution. Blood tests showed thrombocytopenia, CRP 96.9mg/L, ferritin 3021ng/mL and hypertriglyceridemia. Blood and urine cultures were negative. Viral serologies (hepatitis B and C, HIV, parvovirus, CMV, HSV), atypical bacteria (Borrelia, Chlamydia, Coxiella) and screening for latent tuberculosis were also negative. Thoracoabdominal CT scan only showed splenomegaly. The bone marrow aspirate revealed immature lymphoid cells and a hemophagocyte figure, fulfilling the criteria for hemophagocytic syndrome, starting corticosteroid therapy at a dose of 1mg/Kg. Subsequently, the existence of an intrasinusoidal CD3 + CD5- lymphoid infiltrate and a FISH study with isochromosome 7q was reported, a characteristic pattern of hepatosplenic T-cell lymphoma (HSTCL). The study was completed with liver biopsy appreciating a 70% infiltration of T lymphocytes (50% gamma-delta) therefore the diagnosis was confirmed. Chemotherapy (cyclophosphamide, doxorubicin, vincristine, etoposide) was started with the aim of considering hematopoietic stem cell transplantation. Unfortunately, the patient died 6 months later.

Recommendations on prevention of infections in patients with T-cell lymphomas: a narrative review and synthesis.

T/Natural killer (NK) cell lymphomas (TCL) represent a heterogenous subgroup of non-Hodgkin lymphoma, associated with poorer prognosis and higher treatment toxicity. A cohesive synthesis of infection outcomes among TCL patients is lacking. International guidelines offer no specific recommendations regarding prophylaxis or supportive infection care for TCL patients. This systematic narrative review highlights infection outcomes in TCL patients treated with conventional, and novel therapies. Recommendations for infection screening, antimicrobial prophylaxis and vaccination strategies are outined.

Subcutaneous panniculitis-like T-cell lymphoma in two unrelated individuals with BENTA disease.

Subcutaneous panniculitis-like T-cell lymphoma (SPTCL) is a rare primary cutaneous non-Hodgkin lymphoma involving CD8+ T cells, the genetic underpinnings of which remain incompletely understood. Here we report two unrelated patients with B cell Expansion with NF-κB and T cell Anergy (BENTA) disease and a novel presentation of SPTCL. Patient 1 presented early in life with recurrent infections and B cell lymphocytosis, linked to a novel gain-of-function (GOF) CARD11 mutation (p.Lys238del). He developed SPTCL-like lesions and membranoproliferative glomerulonephritis by age 2, treated successfully with cyclosporine. Patient 2 presented at 13 months with splenomegaly, lymphadenopathy, and SPTCL with evidence of hemophagocytic lymphohistiocytosis. Genetic analysis revealed two in cis germline GOF CARD11 variants (p.Glu121Asp/p.Gly126Ser). Autologous bone marrow transplant resulted in SPTCL remission despite persistent B cell lymphocytosis. These cases illuminate an unusual pathological manifestation for BENTA disease, suggesting that CARD11 GOF mutations can manifest in cutaneous CD4+and CD8+ T cell malignancies.

Hepatosplenic T-cell lymphoma presented with massive splenomegaly and pancytopenia - a case report.

BACKGROUND: Hepatosplenic T-cell lymphoma (HSTCL) is a rare subtype of peripheral T-cell lymphoma. Patients usually present with splenomegaly and pancytopenia but without lymphadenopathy. Immunohistochemistry (IHC) staining of bone marrow biopsy shows intra-sinusoidal infiltration of CD3 and CD56 T-lymphocytes. Current treatment strategy of HSTCL includes a CHOP regimen (cyclophosphamide, adriamycine, vincristine, prednisone) followed by autologous transplantation. CASE: A 28-year-old male presented with abdominal fullness, weight loss, and massive splenomegaly. Laboratory findings revealed pancytopenia. A CT scan of the abdomen displayed hepatomegaly and massive splenomegaly. The bone marrow pathology examination showed monotonous medium-sized lymphocytes with some cluster of atypical lymphocytes with loosely condensed chromatin and pale cytoplasm. The intra-sinusoidal location was more prominent after using IHC staining of CD3 and CD56, which are characteristics of HSTCL. We administered CHOP-based regiment every 3 weeks for 3 cycles; however, the response was a stable disease. Since the splenomegaly was still massive and compromised the patient, the multidisciplinary team decided to perform splenectomy. Unfortunately, the patient did not survive the surgery. CONCLUSION: Hepatosplenic T-cell lymphoma is a rare aggressive disease, which is part of peripheral T-cell lymphoma. CHOP-based chemotherapy appeared to be ineffective, and we need further studies to find the optimal treatment of HSTCL.

[Efficiency and safety analysis of Plerixafor combined with granulocyte colony-stimulating factor on autologous hematopoietic stem cell mobilization in lymphoma].

Objective: To evaluate the advantages and safety of Plerixafor in combination with granulocyte colony-stimulating factor (G-CSF) in autologous hematopoietic stem cell mobilization of lymphoma. Methods: Lymphoma patients who received autologous hematopoietic stem cell mobilization with Plerixafor in combination with G-CSF or G-CSF alone were obtained. The clinical data, the success rate of stem cell collection, hematopoietic reconstitution, and treatment-related adverse reactions between the two groups were evaluated retrospectively. Results: A total of 184 lymphoma patients were included in this analysis, including 115 cases of diffuse large B-cell lymphoma (62.5%) , 16 cases of classical Hodgkin's lymphoma (8.7%) , 11 cases of follicular non-Hodgkin's lymphoma (6.0%) , 10 cases of angioimmunoblastic T-cell lymphoma (5.4%) , 6 cases of mantle cell lymphoma (3.3%) , and 6 cases of anaplastic large cell lymphoma (3.3%) , 6 cases of NK/T-cell lymphoma (3.3%) , 4 cases of Burkitt's lymphoma (2.2%) , 8 cases of other types of B-cell lymphoma (4.3%) , and 2 cases of other types of T-cell lymphoma (1.1%) ; 31 patients had received radiotherapy (16.8%) . The patients in the two groups were recruited with Plerixafor in combination with G-CSF or G-CSF alone. The baseline clinical characteristics of the two groups were basically similar. The patients in the Plerixafor in combination with the G-CSF mobilization group were older, and the number of recurrences and third-line chemotherapy was higher. 100 patients were mobilized with G-CSF alone. The success rate of the collection was 74.0% for one day and 89.0% for two days. 84 patients in the group of Plerixafor combined with G-CSF were recruited successfully with 85.7% for one day and 97.6% for two days. The success rate of mobilization in the group of Plerixafor combined with G-CSF was substantially higher than that in the group of G-CSF alone (P=0.023) . The median number of CD34(+) cells obtained in the mobilization group of Plerixafor combined with G-CSF was 3.9×10(6)/kg. The median number of CD34(+) cells obtained in the G-CSF Mobilization group alone was 3.2×10(6)/kg. The number of CD34(+) cells collected by Plerixafor combined with G-CSF was considerably higher than that in G-CSF alone (P=0.001) . The prevalent adverse reactions in the group of Plerixafor combined with G-CSF were grade 1-2 gastrointestinal reactions (31.2%) and local skin redness (2.4%) . Conclusion: The success rate of autologous hematopoietic stem cell mobilization in lymphoma patients treated with Plerixafor combined with G-CSF is significantly high. The success rate of collection and the absolute count of CD34(+) stem cells were substantially higher than those in the group treated with G-CSF alone. Even in older patients, second-line collection, recurrence, or multiple chemotherapies, the combined mobilization method also has a high success rate of mobilization.

NK/T-cell Lymphoma With Orbital Involvement: A Case Report and Systematic Review of the Literature.

PURPOSE: To present the clinical course of a patient with recurrent NK/T-cell lymphoma (NKTL) involving the orbit and to review the literature on patients with NKTL involving the orbit. METHODS: The PubMed database was searched for all cases of NKTL involving orbital, intraocular, or adnexal ocular structures. RESULTS: Ninety-six patients were included in the final analysis. The mean age of diagnosis was 48.1 ± 16.8 years. The patients were 53/96 (55.2%) male and 43/96 (44.8%) female. Tumor location varied and included the orbit in 80/96 (83.3%), nasosinus in 56/96 (58.3%), uvea in 11/96 (11.5%), lacrimal gland in 9/96 (9.4%), lacrimal drainage system in 11/96 (11.5%), and conjunctiva in 7/96 (7.3%) cases. Management included surgical debulking in 29/96 (30.2%) cases, radiotherapy in 52/96 (54.2%) cases, and chemotherapy in 82/96 (85.4%) cases. Median survival was 6 months (95% CI: 5-9). Chemotherapy (hazard ratio = 0.80, 95% CI: 0.67-0.95, p = 0.013), radiotherapy (hazard ratio = 0.75, 95% CI: 0.64-0.87, p < 0.001), and orbital involvement being a recurrence of disease (hazard ratio = 0.79, 95% CI: 0.67-0.95, p = 0.009) were associated with improved survival. Advanced Ann Arbor stage (III-IV) at diagnosis (hazard ratio = 1.22, 95% CI: 1.08-1.38, p = 0.001), vision loss (hazard ratio = 1.18, 95% CI: 1.04-1.34, p = 0.009), proptosis (hazard ratio = 1.15, 95% CI: 1.01-1.30, p = 0.035) and periorbital swelling (hazard ratio = 1.15, 95% CI: 1.00-1.33, p = 0.048) were associated with poor survival. CONCLUSIONS: NK/T-cell lymphoma involving the orbit, globe, or ocular adnexa heralds a poor prognosis where early diagnosis and therapy are critical. The use of radiotherapy and chemotherapy is associated with improved survival.

Refractory hepatosplenic T-cell lymphoma was successfully treated with salvage allogeneic hematopoietic stem cell transplantation combined with enhanced myeloablative preconditioning.

This study aims to evaluate the clinical benefit of salvage allogeneic hematopoietic stem cell transplantation (allo-HSCT) in combination with enhanced myeloablative preconditioning in the treatment of refractory liver and spleen T-cell lymphomas. A retrospective analysis was performed on three patients (with refractory liver and spleen T-cell lymphomas) who have been treated with salvage allo-HSCT combined with enhanced myeloablative preconditioning. One of three patients had a liver biopsy; the other two underwent bone marrow analysis using morphology, immunology, cytogenetics, and molecular biology. All three patients were resistant to chemotherapy and with a high tumor load, so a new total body irradiation/splenic region irradiation/GEM/CLAG/ATG preconditioning regimen was conducted and followed with salvage HSCT. Two patients received haploidentical-donor hematopoietic stem cell transplants, and one received an unrelated full-donor hematopoietic stem cell transplant. The three patients survived disease-free until May 2021. Clinically, hepatosplenic T-cell lymphoma (HSTCL) is rare, with a poor prognosis and chemotherapy response. Based on the present study's encouraging clinical results, salvage allo-HSCT in conjunction with an enhanced myeloablative preconditioning regiment may be an effective and safe treatment for HSTCL.

Diagnosis and Treatment of Subcutaneous Panniculitis-like T-cell Lymphoma: A Systematic Literature Review.

OBJECTIVES: The aim of this systematic review is to investigate different diagnostic methods and the available treatment options for subcutaneous panniculitis-like T-cell lymphoma (SPTCL). METHODS: We searched PubMed, Web of Science, SCOPUS, EBSCO, and CINAHL Plus for published case reports of SPTCL. From each record, we extracted data of the diagnostic methods, immunohistochemical profile, clinical characteristics, and the treatment approaches provided. Data were summarized and narratively synthesized to highlight the various diagnostic methods and treatment options of SPTCL. RESULTS: Our literature search yielded 1293 unique citations. Following screening, nine articles reporting a total of 15 cases were included in this systematic review. All patients presented with subcutaneous nodules. Three of the 15 cases were initially misdiagnosed. The atypical lymphoid cells were positive for CD2, CD3, granzyme B, and TIA-1 and negative for CD1a, EBER, and CD20 in all the reported cases. The atypical lymphoid cells were positive for CD45RO in four out of seven cases, positive for CD56 in three out of 12 cases tested, while positive for CD5 and CD8 in the majority of cases. Therapy ranged from topical agents to immunosuppressive agents all the way to multiagent chemotherapy. CONCLUSION: SPTCL is a rare lymphoma. Diagnosis is highly dependent on the immunohistochemical stains added to histopathologic and radiologic findings. Therapy is dependent on the pace of the disease, with encouraging results obtained with single-agent cyclosporine.

Efficiency and safety analysis of Plerixafor combined with granulocyte colony-stimulating factor on autologous hematopoietic stem cell mobilization in lymphoma / 中华血液学杂志

Objective: To evaluate the advantages and safety of Plerixafor in combination with granulocyte colony-stimulating factor (G-CSF) in autologous hematopoietic stem cell mobilization of lymphoma. Methods: Lymphoma patients who received autologous hematopoietic stem cell mobilization with Plerixafor in combination with G-CSF or G-CSF alone were obtained. The clinical data, the success rate of stem cell collection, hematopoietic reconstitution, and treatment-related adverse reactions between the two groups were evaluated retrospectively. Results: A total of 184 lymphoma patients were included in this analysis, including 115 cases of diffuse large B-cell lymphoma (62.5%) , 16 cases of classical Hodgkin's lymphoma (8.7%) , 11 cases of follicular non-Hodgkin's lymphoma (6.0%) , 10 cases of angioimmunoblastic T-cell lymphoma (5.4%) , 6 cases of mantle cell lymphoma (3.3%) , and 6 cases of anaplastic large cell lymphoma (3.3%) , 6 cases of NK/T-cell lymphoma (3.3%) , 4 cases of Burkitt's lymphoma (2.2%) , 8 cases of other types of B-cell lymphoma (4.3%) , and 2 cases of other types of T-cell lymphoma (1.1%) ; 31 patients had received radiotherapy (16.8%) . The patients in the two groups were recruited with Plerixafor in combination with G-CSF or G-CSF alone. The baseline clinical characteristics of the two groups were basically similar. The patients in the Plerixafor in combination with the G-CSF mobilization group were older, and the number of recurrences and third-line chemotherapy was higher. 100 patients were mobilized with G-CSF alone. The success rate of the collection was 74.0% for one day and 89.0% for two days. 84 patients in the group of Plerixafor combined with G-CSF were recruited successfully with 85.7% for one day and 97.6% for two days. The success rate of mobilization in the group of Plerixafor combined with G-CSF was substantially higher than that in the group of G-CSF alone (P=0.023) . The median number of CD34(+) cells obtained in the mobilization group of Plerixafor combined with G-CSF was 3.9×10(6)/kg. The median number of CD34(+) cells obtained in the G-CSF Mobilization group alone was 3.2×10(6)/kg. The number of CD34(+) cells collected by Plerixafor combined with G-CSF was considerably higher than that in G-CSF alone (P=0.001) . The prevalent adverse reactions in the group of Plerixafor combined with G-CSF were grade 1-2 gastrointestinal reactions (31.2%) and local skin redness (2.4%) . Conclusion: The success rate of autologous hematopoietic stem cell mobilization in lymphoma patients treated with Plerixafor combined with G-CSF is significantly high. The success rate of collection and the absolute count of CD34(+) stem cells were substantially higher than those in the group treated with G-CSF alone. Even in older patients, second-line collection, recurrence, or multiple chemotherapies, the combined mobilization method also has a high success rate of mobilization.

[Primary testicular NK/T cell lymphoma. Case report and review of literature]. / Linfoma de células T/NK primario de testículo. Caso clínico y revisión de la literatura.

Natural killer/T cell lymphomas chiefly involving the midline facial structures including the nasal cavity or nasopharyns are a relatively rare type of non-Hodgkin's lymphoma. Apart from the upper respiratory tract, the disease occasionally presents in certain extranodal sites, such as the central nervous system, skin, gastrointestinal tract, or testes. We report a case of natural killer NK/T cell lymphoma as a testicular tumor in a 36-year-old man with a history of progressive swelling of his right testicle. Histologically, the testicular mass showed a diffuse infiltrate of medium-sized and atypical large lymphoid cells with angiocentric infiltration and areas of coagulative necrosis. Immunohistochemical studies demonstrated tumor cells staining positively with CD3, TIA-1, and Granzyme B. The Epstein-Barr virus genoma was detected by in situ hybridization. There were no abnormal findings in the nasal and nasopharyngeal regions. Classified as stage IEA, the patient received involved-field irradiation to contralateral testis (45 Gy), followed by systemic chemotherapy with a combination regimen ofL-asparaginase, methotrexate and dexamethasone. Relevant literature is reviewed, and the clinicopathologic features, natural history, and treatment options for primary testicular NK/T cell lymphoma are discussed.

Clinical and Pathological Characteristics and Outcomes Among Patients With Subcutaneous Panniculitis-like T-Cell Lymphoma and Related Adipotropic Lymphoproliferative Disorders.

Importance: There is a knowledge gap about subcutaneous panniculitis-like T-cell lymphoma (SPTCL) owing to its rarity and diagnostic difficulty, resulting in an absence of well-documented large case series published to date. Objective: To generate consensus knowledge by a joint multi-institutional review of SPTCL and related conditions. Design, Setting, and Participants: This retrospective clinical and pathological review included cases initially diagnosed as SPTCL at 6 large US academic centers. All cases were reviewed by a group of pathologists, dermatologists, and oncologists with expertise in cutaneous lymphomas. Through a process of group consensus applying defined clinical and pathological diagnostic criteria, the cohort was classified as (1) SPTCL or (2) adipotropic lymphoproliferative disorder (ALPD) for similar cases with incomplete histopathological criteria for SPTCL designation. Exposures: Cases of SPTCL diagnosed between 1998 and 2018. Main Outcomes and Measures: The main outcome was disease presentation and evolution, including response to therapy, disease progression, and development of hemophagocytic lymphohistiocytosis. Results: The cohort of 95 patients (median [range] age, 38 [2-81] years; female-to-male ratio, 2.7) included 75 cases of SPTCL and 20 cases of ALPD. The clinical presentation was similar for both groups with multiple (61 of 72 [85%]) or single (11 of 72 [15%]) tender nodules mostly involving extremities, occasionally resulting in lipoatrophy. Hemophagocytic lymphohistiocytosis (HLH) was only observed in SPTCL cases. With a mean follow-up of 56 months, 60 of 90 patients (67%) achieved complete remission with a median (range) of 3 (1-7) cumulative therapies. Relapse was common. None of the patients died of disease progression or HLH. Two patients with ALPD eventually progressed to SPTCL without associated systemic symptoms or HLH. Conclusions and Relevance: In this case series of patients initially diagnosed as having SPTCL, results showed no evidence of systemic tumoral progression beyond the adipose tissue. The SPTCL experience in this study confirmed an indolent course and favorable response to a variety of treatments ranging from immune modulation to chemotherapy followed by hematopoietic stem cell transplantation. Morbidity was primarily associated with HLH.