Treatment outcomes between cyclosporin and chemotherapy in adult subcutaneous panniculitis-like T-cell lymphoma: a report from nation-wide Thai lymphoma study group registry.

Subcutaneous panniculitis-like T-cell lymphoma (SPTCL) is a rare subtype of T-cell lymphomas with a characteristic feature of subcutaneous nodules associated with hemophagocytic lymphohistiocytosis (HLH). Treatment options for SPTCL are mainly chemotherapy (CMT) or immunosuppressive agents with selection currently dependent on physician decisions. Outcomes between the 2 treatment remedies have not yet been comprehensively compared. This study aimed to compare complete remission (CR) rates between SPTCL patients receiving cyclosporin (CSA)-based regimen (CSA +/- steroid) and CMT. The 5-year overall survival (OS) and 5-year progression free survival (PFS) were also analyzed. Clinical data from patients with SPTCL were drawn from the Thai Lymphoma Study Group registry who were newly diagnosed between 2007 and 2023. A total of 93 patients were selected with 45 cases having received CSA-based regimen and 48 cases having received CMT. There were more patients with limited stage at skin in the CSA group (63.8% vs. 36.2%, p = 0.003), while more patients with hepato- and/or splenomegaly were found in the CMT group (56.2% vs. 24.5%; p = 0.002). Germline HAVCR2 mutations were detected in 26/33 (78.8%) cases. The CR rate was significantly higher in patients treated with CSA (87% vs. 58.3%; OR = 6.5 [95%CI, 2.7-15.3]; p = 0.002). At a median follow-up of 87.8 months (range 0-185), the 5-year OS (98% vs. 87%, p = 0.19) and PFS (72.4% vs. 69.2%, p = 0.19) showed a trend favoring patients treated with CSA. Based on our study, CSA-based regimens are the preferred first-line treatment remedy for newly diagnosed SPTCL, especially in patients with limited cutaneous involvement.

Clinical analysis of 10 cases with subcutaneous panniculitis-like T-cell lymphoma and tissue AURKA expression.

BACKGROUND: Due to its rarity, subcutaneous panniculitis-like T-cell lymphoma (SPTCL) is often misdiagnosed as benign panniculitis, and there are no standardized treatment guidelines for SPTCL. Aurora kinase A (AURKA) plays a regulatory role in both mitosis and meiosis. Cells treated with an AURKA inhibitor showed severe mitotic delay, which triggered apoptosis. MATERIALS AND METHODS: Ten cases of SPTCL were collected in this study, and immunohistochemistry was performed to detect AURKA expression in the skin tissues of these cases. Control groups were set as follows: 1) 10 cases of inflammatory panniculitis; 2) 9 healthy individuals. Fisher's exact test was used to compare the positive rates of AURKA among various groups. RESULTS: An average onset age of 27.3 years was found in 10 SPTCL cases. Clinically, these patients primarily presented with multiple subcutaneous nodules on the trunk and lower extremities, accompanied by intermittent high fever. One case showed lymph node metastasis, while no other distant organ metastasis being observed in any case. Pathologically, there was an infiltration of a large number of atypical lymphocytes within the fat lobules, characterized as a cytotoxic type. AURKA stanning was positive in 6 out of 10 SPTCL cases, while no positive cases were found in the control groups. CONCLUSION: 1) SPTCL predominantly affects young individuals and can be identified by nodular erythema on the trunk, intermittent high fever, and infiltration of atypical cytotoxic lymphocytes within fat lobules. 2) For early-stage cases without metastasis, monotherapy with glucocorticoids or immunosuppressants such as cyclosporine can be considered. 3) High expression of AURKA in SPTCL tissues suggests that AURKA could be a potential biomarker for disease diagnosis, providing a theoretical basis for further targeted therapy.

Hemophagocytic Lymphohistiocytosis in the Context of Hematological Malignancies and Solid Tumors.

Hemophagocytic lymphohistiocytosis (HLH) has been described for decades in association with malignancies (M-HLH). While its mechanism is unknown, M-HLH has a poor prognosis, ranging from 10% to 30% overall survival. Mature T-cell lymphomas, diffuse large B-cell lymphoma, and Hodgkin lymphoma, with or without viral co-triggers such as Epstein-Barr virus, are among the most frequent underlying entities. Most M-HLH cases occur at the presentation of malignancy, but they may also occur during therapy as a result of immune compromise from chemotherapy (HLH in the context of immune compromise, IC-HLH) and (typically) disordered response to infection or after immune-activating therapies (Rx-HLH, also known as cytokine release syndrome, CRS). IC-HLH typically occurs months after diagnosis in the context of fungal, bacterial, or viral infection, though it may occur without an apparent trigger. Rx-HLH can be associated with checkpoint blockade, chimeric antigen receptor T-cell therapy, or bispecific T-cell engaging therapy. Until recently, M-HLH diagnosis and treatment strategies were extrapolated from familial HLH (F-HLH), though optimized diagnostic and therapeutic treatment strategies are emerging.

Different mutational profiles of subcutaneous panniculitis-like T-cell lymphoma and lupus panniculitis: an additional case series.

BACKGROUND AND OBJECTIVE: subcutaneous panniculitis-like T-cell lymphoma (SPTCL) is a rare cytotoxic T-cell lymphoma with indolent behavior, mostly present in women and associated with immunological diseases whose pathogenic background is still poorly understood. SPTCL is associated with lupus erythematosus panniculitis (LEP) and histologically misdiagnosed. OBJECTIVES: the aim of our study was to identify mutations affecting the pathogenesis of both SPTCL and LEP. MATERIALS AND METHODS: we studied a total of 10 SPTCL and 10 LEP patients using targeted Next Generation Sequencing and pyrosequencing. Differences in gene expression between molecular subgroups were investigated using NanoString technology. Clinical data were collected, and correlations sought with the molecular data obtained. RESULTS: the mutational profile of SPTCL and LEP is different. We identified fewer pathogenic mutations than previously reported in SPTCL, noting a single HAVCR2-mutated SPTCL case. Interestingly, 40% of our SPTCL cases showed the pathogenic TP53 (p.Pro72Arg) (P72R) variant. Although cases showing HAVCR2 mutations or the TP53 (P72R) variant had more severe symptomatic disease, none developed hemophagocytic syndrome (HPS). Furthermore, TP53 (P72R)-positive cases were characterized by a lower metabolic signaling pathway and higher levels of CD28 expression and Treg signaling genes. In addition, 30% of our cases featured the same mutation (T735C) of the epigenetic modificatory gene DNMT3A. None of the LEP cases showed mutations in any of the studied genes. CONCLUSIONS: the mutational landscape of SPTCL is broader than previously anticipated. We describe, for the first time, the involvement of the TP53 (P72R) pathogenic variant in this subgroup of tumors, consider the possible role of different genetic backgrounds in the development of SPTCL, and conclude that LEP does not follow the same pathogenic pathway as SPTCL.

Primary cutaneous gamma-delta T-cell lymphoma masquerading as leukemia cutis in a patient recently diagnosed with small lymphocytic lymphoma: Clues to the diagnosis.

A 54-year-old man recently diagnosed with small lymphocytic lymphoma (SLL) had waxing and waning, indurated, erythematous plaques on his legs, with leukopenia and anemia disproportionate to the SLL burden in his marrow and pelvic lymph nodes. Punch biopsy of a plaque performed to evaluate for leukemia cutis revealed a lymphocytic lobular-panniculitis-like infiltrate resembling lupus panniculitis, but a preponderance of CD8+/Ki-67+ T-cells surrounding adipocytes raised concern for subcutaneous panniculitis-like T-cell lymphoma (SPTCL). Additional immunohistochemistry (IHC) studies showed that the adipotropic T-cells expressed TCR-gamma, supporting the rare, unexpected diagnosis of Primary cutaneous gamma-delta T-cell lymphoma (PCGDTCL). The patient subsequently met diagnostic criteria for hemophagocytic lymphohistiocytosis (HLH). PCGDTCL is an aggressive, HLH-associated lymphoma requiring different management than SPTCL and SLL. This case illustrates how PCGDTCL can co-exist with B-cell lymphoma and resemble panniculitis on biopsies. PCGDTCL and SPTCL should enter the differential diagnosis whenever patients present with the constellation of lobular panniculitis and unexplained cytopenias. In the present case, close clinicopathologic correlation and judicious use of IHC on a small sample allowed for a prompt diagnosis.

Ruxolitinib as adjunctive therapy for secondary hemophagocytic lymphohistiocytosis: A case series.

INTRODUCTION: Hemophagocytic lymphohistiocytosis (HLH) is a cytokine storm syndrome associated with mortality rates of up to 88%. Standard therapy with high-dose glucocorticoids and etoposide used in adults is extrapolated from pediatric trials, with significant toxicity in older patients and those with poor performance status. The JAK1/2 inhibitor ruxolitinib has recently gained attention as a treatment option for HLH due to its broad cytokine-modulating abilities and safety profile. Herein we report our center's experience using ruxolitinib in the treatment of adult-onset secondary HLH. CASE SERIES: We report four patients with profound secondary HLH provoked by diverse triggers, including invasive pulmonary aspergillosis on background systemic lupus erythematosus, disseminated tuberculosis, and T-cell lymphoma treated with ruxolitinib as monotherapy or combination therapy in upfront and salvage settings. RESULTS: All four patients had rapid, sustained improvement in clinical status, inflammatory markers, and hematological cell counts followed by durable remission. Three patients developed manageable infectious complications postruxolitinib. CONCLUSIONS: This series demonstrates the effective use of JAK inhibition with ruxolitinib to control pathological immune activation in critically ill patients with secondary HLH and otherwise limited therapeutic options. JAK inhibition is also an area of urgent investigation for the treatment of cytokine storm associated with COVID-19.

Primary cutaneous T-cell lymphomas other than mycosis fungoides and Sézary syndrome. Part I: Clinical and histologic features and diagnosis.

Primary cutaneous T-cell lymphomas (CTCLs) are defined as lymphomas with a T-cell phenotype that present in the skin without evidence of systemic or extracutaneous disease at initial presentation. CTCLs other than mycosis fungoides and Sézary syndrome (SS) account for approximately one third of CTCLs and encompass a heterogenous group of non-Hodgkin lymphomas, ranging from indolent lymphoproliferative disorders to aggressive malignancies with a poor prognosis. The spectrum of CTCLs continues to broaden as new provisional entities are classified. Given the morphologic and histologic overlap among CTCLs and other diagnoses, a thorough clinical history, physical evaluation, and clinicopathologic correlation are essential in the work up and diagnosis of these rare entities. This article will summarize the epidemiologic, clinical, pathologic, and diagnostic features of CTCLs other than mycosis fungoides and SS.

Primary cutaneous T-cell lymphomas other than mycosis fungoides and Sézary syndrome. Part II: Prognosis and management.

Primary cutaneous T-cell lymphomas (CTCLs) other than mycosis fungoides (MF) and Sézary syndrome (SS) encompass a heterogenous group of non-Hodgkin lymphomas with variable clinical courses, prognoses, and management approaches. Given the morphologic and histologic overlap among the CTCL subtypes and other T-cell lymphomas with cutaneous manifestations, thorough evaluation with clinicopathologic correlation and exclusion of systemic involvement are essential prior to initiating therapy. Staging and treatment recommendations vary, depending on the subtype, clinical behavior, and treatment response. Generally, for subtypes in which staging is recommended, Ann Arbor or tumor, node, metastasis staging specific to CTCL other than MF or SS are used. For many subtypes, there is no standard treatment to date. Available recommended treatments range widely, from no active or minimal intervention with skin-directed therapy to aggressive systemic therapies that include multi-agent chemotherapy with consideration for hematopoietic stem cell transplant. Emerging targeted therapies, such as brentuximab, a chimeric antibody targeting CD30, show promise in altering the disease course of non-MF/SS CTCLs.

Unraveling subcutaneous panniculitis-like T-cell lymphoma: An association between subcutaneous panniculitis-like T-cell lymphoma, autoimmune lymphoproliferative syndrome, and familial hemophagocytic lymphohistiocytosis.

Germline HAVCR2 mutations, recently identified in a large subset of patients with subcutaneous panniculitis-like T-cell lymphoma (SPTCL), are associated with an increased risk of hemophagocytic lymphohistiocytosis (HLH). Discovery of this heritable HLH/SPTCL diathesis has expanded our understanding of a rare and molecularly heterogeneous lymphoma. Furthermore, patients with SPTCL have excellent survival unless they develop HLH. Therefore, through compiling data on SPTCL-related conditions that predispose patients to HLH, we are better able to predict which patients with SPTCL have the greatest risk of mortality. We present the first case of SPTCL with concomitant HLH and autoimmune lymphoproliferative syndrome (ALPS) in a patient who was subsequently diagnosed with familial HLH (F-HLH) attributable to a germline STXBP2 splice-site mutation. She had wild-type HAVCR2. Reports including ours show how SPTCL can evolve in the setting of an exaggerated host inflammatory response attributable to a variety of unusual underlying etiologies.

Subcutaneous panniculitis-like T cell lymphoma presented as erythema nodosum: A case report.

Subcutaneous panniculitis-like T cell lymphoma (SPTCL) is an extremely rare subtype of primary cutaneous T cell lymphomas mimicking panniculitis. Clinically, patients are usually presented with subcutaneous nodules, which usually leads to initial misdiagnosis as a benign cutaneous condition. Here, we report a 40-year-old female who presented with subcutaneous erythematous nodules on her extremities with fever. On the basis of the clinical presentations, histopathological features and immunohistochemical findings, a diagnosis of SPTCL was made. The patient was treated with the injection of recombinant human interferon α-1b (30 µg) every other day for 3 months. The lesions gradually regressed. No new erythema nodules reappeared during the 10-month follow-up.

Subcutaneous panniculitis-like T-cell lymphoma in a 14-year-old female homozygous for HAVCR2 mutation.

Subcutaneous panniculitis-like T-cell lymphoma (SPTCL) is a rare cytotoxic T-cell lymphoma preferentially involving subcutis. A link between patients with SPTCL and HAVCR2 mutations has recently been discovered. We present a 14-year-old girl of Chinese heritage who was diagnosed with SPTCL in the context of homozygous HAVCR2 status for c.245A>G p. (Tyr82Cys) and achieved complete remission after treatment with cyclosporin and steroids. Dermatologists should be aware of the diagnostic, management and familial genetic counselling utility of HAVCR2 for investigating and managing patients with SPTCL.

TIM-3 deficiency presenting with two clonally unrelated episodes of mesenteric and subcutaneous panniculitis-like T-cell lymphoma and hemophagocytic lymphohistiocytosis.

This report offers novel clinical and diagnostic aspects of the association between germline mutations in HAVCR2 and subcutaneous panniculitis-like T-cell lymphoma (SPTCL). The patient presented with panniculitis-like T-cell lymphoma involving mesenteric fatty tissue associated with hemophagocytic lymphohistiocytosis (HLH). Five years later, he developed a clonally unrelated SPTCL and underwent hematopoietic stem cell transplantation. Retrospectively, he was found to carry germline mutations in HAVCR2 associated with reduced T-cell immunoglobulin mucin-3 (TIM-3) expression. We show that mesenteric fatty tissue localization of SPTCL can be the presenting manifestation of TIM-3 deficiency, that this condition predisposes to recurrent lymphoma, and that flow cytometry is a possible screening tool.

Utility of CD123 immunohistochemistry in differentiating lupus erythematosus from cutaneous T cell lymphoma.

AIMS: Histopathological overlap between lupus erythematosus and certain types of cutaneous T cell lymphoma (CTCL) is well documented. CD123+ plasmacytoid dendritic cells (PDCs) are typically increased in lupus erythematosus, but have not been well studied in CTCL. We aimed to compare CD123 immunostaining and histopathological features in these conditions. METHODS AND RESULTS: Skin biopsies of cutaneous lupus erythematosus (CLE, n = 18), lupus erythematosus panniculitis (LEP, n = 17), mycosis fungoides (MF, n = 25) and subcutaneous panniculitis-like T cell lymphoma (SPTCL, n = 9) were retrospectively reviewed and immunostained with CD123. Percentage, distribution and clustering of CD123+ cells were compared between CLE and MF and between LEP and SPTCL using χ2 and two-tailed t-tests. A higher percentage of CD123+ cells was observed in CLE than MF (P < 0.01), more frequently comprising ≥20% of the entire infiltrate (P < 0.01) and forming clusters (P < 0.01). Similarly, LEP showed a higher percentage of CD123+ cells than SPTCL (P = 0.01), more frequently comprising ≥20% of the infiltrate (P = 0.04) and forming clusters (P = 0.01). Basal vacuolar change or dyskeratosis was observed in all CLE cases and in 48% cases of MF cases (P = 0.05). Plasma cells were readily identified in 76% cases of LEP but in none of the SPTCL cases (P = 0.01). Adipocyte rimming by lymphocytes, hyaline fat necrosis and fibrinoid/grungy necrosis did not significantly differ between LEP and SPTCL. Dermal mucin also failed to distinguish between groups. CONCLUSIONS: CD123 immunostaining is helpful in differentiating CLE from MF and LEP from SPTCL, but should be interpreted in conjunction with clinicopathological features and other ancillary studies to ensure accurate diagnosis.

Rare T-Cell Subtypes.

There are a number of rare T-cell lymphoma subtypes that may be encountered in clinical practice. In recent years, improved immunohistochemical techniques and molecular tumor profiling have permitted refinement of some of the diagnostic categories in this group, as well as the recognition of distinct conditions not previously well elucidated. In this chapter, we cover the diagnostic and clinical features of some of the more common of these conditions, including subcutaneous panniculitis-like T-cell lymphoma, cutaneous gamma-delta T-cell lymphoma, enteropathy-associated T-cell lymphoma, monomorphic epitheliotropic intestinal T-cell lymphoma, primary cutaneous CD8-positive aggressive epidermotropic cytotoxic T-cell lymphoma, CD4-positive small/medium T-cell lymphoproliferative disorder, and acral CD8-positive T-cell lymphoma. Given the rarity of these conditions, optimal treatments approaches are not always well established, not least as data from large-scale clinical trials are lacking. In this chapter, we aim to provide a summation of current thinking around best treatment, as well as highlighting some controversies in the management of these diagnoses.

Clinicopathologic, immunophenotypic, and molecular analysis of subcutaneous panniculitis-like T-cell lymphoma: A retrospective study in a tertiary care center.

BACKGROUND: Subcutaneous panniculitis-like T-cell lymphoma (SPTL) as strictly defined by World Health Organization-European Organization for Research and Treatment of Cancer classification is a rare cytotoxic α/ß T-cell lymphoma, characterized by primary involvement of subcutaneous tissue mimicking panniculitis. OBJECTIVES: To describe the clinicopathologic, immunophenotypic, and molecular features of SPTL. METHODS: A 10-year retrospective study of 18 patients diagnosed with SPTL was thoroughly reviewed according to clinicopathology, immunophenotype, and T-cell receptor (TCR) gene rearrangement. RESULTS: Of the 18 patients, 16 patients were definitely diagnosed with SPTL. The median age was 26 years (ranged 14-53 years) with female predominance. Most patients presented with prolonged fever and subcutaneous nodules and/or plaques, usually located on lower extremities. 37.5% of patients had hemophagocytic syndrome. The main histopathology was lobular panniculitis with rimming of atypical lymphocytes highlighted by CD3+, CD8+, Beta-F1+, granzyme B+, and Ki-67 (50%-90%). Monoclonal TCR gene rearrangement was found in 50% of patients and upper extremities involvement indicated a poor prognosis. CONCLUSION: The correlation between clinicopathologic and immunophenotypic study is the most helpful method to give a precise diagnosis of SPTL. Rimming of CD8+ atypical lymphocytes highlighted by high Ki-67 index is highly specific for the diagnosis of SPTL.

[Concurrent subcutaneous panniculitis-like T-cell lymphoma and myelodysplastic syndrome with fibrosis].

A 66-year-old male presented with fever and erythema at our hospital, and leukoerythroblastosis, anemia, thrombocytopenia, and multiple low-density lesions in the moderately enlarged spleen were detected. Skin tissue revealed CD8+ T cells with the expression of cytotoxic molecule markers involving fat lobules, and subcutaneous panniculitis T-cell lymphoma (SPTCL) was diagnosed. The bone marrow displayed no infiltration of lymphoid tumor cells, but hyperplasia of granulocytes and megakaryocytes with grade 2 stromal fibrosis. In addition, the bone marrow exhibited diffuse 18F-fluorodeoxyglucose (FDG) accumulation on FDG positron-emission tomography/computed tomography (FDG-PET/CT). Although chemotherapy improved SPTCL, the patient died from leukocytosis with leukoerythroblastosis. We obtained negative results for the JAK2 V617F mutation, and CD34+ cells were elevated in the bone marrow compared with the levels at initial examination. The final diagnosis was concurrent myelodysplastic syndrome (MDS) with fibrosis and SPTCL. This report highlights that it is essential to consider MDS or other myeloproliferative neoplasms (MPN) as possible complications when malignant lymphoma complicates myelofibrosis in the absence of bone marrow infiltration of lymphoma cells. Perhaps, the assessment of clonal markers of MPN and FDG accumulation patterns in the bone marrow by FDG-PET/CT could enable differentiation.

[Clinical Comparative Analysis of Lupus Panniculitis and Subcutaneous Panniculitis-like T-cell Lymphoma].

OBJECTIVE: To explore the similarities and differences in clinical pathological features and gene rearrangement of lupus erythematosus profundus(LEP) and subcutaneous panniculitis-like T-cell lymphoma(SPTL). METHODS: We compared the clinical presentations, histopathology, immunophenotypical features and T-cell receptor (TCR) gene rearrangement findings of 9 cases of LEP and SPTL. RESULTS: For clinical features, most patients of LEP occurred on head and face without systemic symptoms. LEP patients responded well to hydroxycholorquine treatment with good prognosis. Most patients of SPTL tended to lower extremities involvement and accompanied with systemic symptoms, the patients with disseminated lesions or hemophagocytic syndrome(HPS) showed poorer prognosis. For histopathology, LEP patients showed dense inflammatory infiltrate in the dermis consisting predominantly of lymphocytes with less numbers of plasma cells. However, the dermis was spared in SPTL, and rimming of adipocytes and erythrophagocytosis was observed in SPTL. Lymphocytes of LEP expressing CD4+/CD8+, as well as clusters of CD20+. CD138-positive cells and scatter of CD123-positive cells were also observed in LEP. Tumor cells of SPTL were CD4-/CD8+, ßF1+, CD138- and CD123-. The expression of TIA-1 or GrB was more favor in SPTL. Monoclonal T-cell receptor-γ gene rearrangement was found in 89% of SPTL patients while negative for LEP. CONCLUSION: Base on different clinical and pathological features, it is easy to distinguish LEP from SPTL. However, a minority of lesions in LEP localize at subcutaneous tissue, which may turn to immunophenotypical and TCR gene rearrangement test for diagnosis.

Subcutaneous panniculitis-like T-cell lymphoma: Clinical features, therapeutic approach, and outcome in a case series of 16 patients.

BACKGROUND: Subcutaneous panniculitis-like T-cell lymphoma (SPTCL) is a rare primary cutaneous lymphoma of mature cytotoxic T cells. Initially, patients with SPTCL were treated with doxorubicin-based polychemotherapy. OBJECTIVE: To analyze clinical, biologic, immunophenotypical, molecular, imaging, treatment, and outcome data reflecting the current state of knowledge. METHODS: A retrospective multicenter study of 16 patients with SPTCL that was diagnosed between 1996 and 2016. RESULTS: The female-to-male ratio was 1.7. The median age at diagnosis was 46.5 years. Patients presented with multiple nodular or plaque-like lesions preferentially affecting the legs and/or trunk. Histopathology typically showed a lobular panniculitis with individual adipocytes surrounded by atypical lymphocytes, usually with a CD3+, CD4-, CD8+, CD56-, TIA1 cytotoxic granule associated RNA binding protein 1-positive phenotype and high proliferation rate. SPTCL was associated with autoimmune diseases in 25% of patients, and with the development of hemophagocytic syndrome in 18% of patients. Oral steroids alone or in combination with low-dose methotrexate or cyclosporine A were the most common initial treatment, achieving a complete response in 85% of the treated patients. The median follow-up time was 14 months. The 5-year disease-specific survival rate was 85.7%. LIMITATIONS: This was a retrospective study. CONCLUSIONS: SPTCL has an excellent prognosis. Immunosuppressive agents can be considered for first-line treatment.

Composite cutaneous lymphoma of diffuse large B-cell lymphoma-leg type and subcutaneous panniculitis-like T-cell lymphoma.

Composite lymphoma (CL) is a rare disease defined by the occurrence of two distinct lymphomas within a single tissue at the same time. We present the case of an 89-year-old male with a clinical history of immunoglobulin M monoclonal gammopathy of undetermined significance. The patient presented cutaneous eruption of nodules on the right bottom and arm. An excisional biopsy revealed cutaneous infiltration composed of two components. The first one consisted of large B-cells with CD20+/MUM1+/BCL2+ phenotype whereas the second one involved the subcutaneous fat in a panniculitic manner, and was CD3+/CD8+/granzyme B+/TCRßF1+. The final diagnosis was CL of primary cutaneous large B-cell lymphoma-leg type (PCLBCL-leg type) and subcutaneous panniculitis-like T-cell lymphoma (SPTCL). We report and characterize for the first time coexistent PCLBCL-leg type and SPTCL in a patient.

Immunohistochemistry reveals an increased proportion of MYC-positive cells in subcutaneous panniculitis-like T-cell lymphoma compared with lupus panniculitis.

BACKGROUND: Subcutaneous panniculitis-like T-cell lymphoma (SPTCL) is a malignant primary cutaneous T-cell lymphoma that shares significant clinical, histopathologic and immunophenotypic overlap with lupus erythematosus panniculitis (LEP). METHODS: We performed immunohistochemistry for the MYC oncoprotein on 23 cases of SPTCL (1 CD8 negative) and 12 cases of LEP to evaluate if there are quantitative or qualitative differences in protein expression of this marker in these entities. RESULTS: In SPTCL cases, the percentage of all cells that were c-Myc positive ranged from 0.8% to 16%, with a mean of 5.0% and a median of 4.4%. In contrast, in the LEP cases, the percentage of c-Myc-positive cells in the cases ranged from 0.34% to 3.7%, averaged 1.4% and the median was 0.8%. The difference between the means of these 2 diagnostic categories was statistically significant. Fluorescence in situ hybridization performed on 4 cases of SPTCL with a relatively high level of MYC immunohistochemical staining, however, failed to demonstrate evidence of MYC rearrangement or amplification. CONCLUSIONS: Our work demonstrates that MYC expression levels differ between these 2 histologic mimics and suggests that this important oncoprotein may play a role in the pathogenesis of SPTCL.