Utility of T-cell immunosequencing in distinguishing mycosis fungoides progression from treatment related cutaneous adverse events

Cutaneous adverse events of both topical and systemic drugs in patients with mycosis fungoides (MF) present a diagnostic challenge as it is often difficult to distinguish drug associated rash from disease progression in the skin. Mogamulizumab and mechlorethamine gel are approved treatments for MF, both of which can cause treatment related cutaneous adverse events. It can often be challenging to distinguish mogamulizumab associated rash (MAR) and mechlorethamine gel associated hypersensitivity dermatitis from MF progression both clinically and histologically. High-throughput sequencing (HTS) of the T-cell receptor (TCR), also known as immunosequencing, can be used to assess T-cell clonality to support a diagnosis of MF. After identification of the malignant TCR clone at baseline, immunosequencing can track the established malignant TCR sequence and its frequency over time with high sensitivity. As a result, immunosequencing clone tracking can aid in distinguishing disease progression from treatment side effects. Here, we present a case series to demonstrate how monitoring of the malignant T-cell frequency by immunosequencing can aid in diagnosis of mogamulizumab and mechlorethamine gel cutaneous adverse events

Immunosequencing Applications in Cutaneous T-Cell Lymphoma

Immunosequencing has emerged as a newer clinical test for assessment of T-cell clonality in the blood and skin of cutaneous T-cell lymphoma (CTCL) patients. Utilization of immunosequencing, also known as high-throughput sequencing of the T-cell receptor (HTS-TCR), enables identification and quantification of the precise genetic signature of dominant T-cell clones. Although immunosequencing is more sensitive than commonly used methods such as polymerase chain reaction (PCR) paired with capillary electrophoresis or flow cytometry, it remains underutilized for CTCL management. Nonetheless, incorporation of HTS-TCR in clinical practice offers distinct advantages compared to other molecular analyses that may improve diagnostic evaluation, prognostication, and disease monitoring in CTCL. The objective of this comprehensive review is to provide a thorough explanation of the application of immunosequencing in the context of CTCL. We describe the significance of T-cell clonality and the methods used to detect it, including a detailed comparison between PCR paired with capillary electrophoresis and HTS-TCR. The utilization of immunosequencing in the blood and skin of CTCL patients is discussed in depth, specifically outlining how HTS-TCR can assist in diagnosing CTCL, predicting outcomes, and tracking disease progression. Finally, we address the potential applications of immunosequencing in clinical management and research as well as the novel challenges it presents

Neutrophilic Panniculitis Associated With Myelodysplastic Syndrome/Myeloproliferative Neoplasm: A Case Report and Literature Review

INTRODUCTION: Neutrophilic panniculitis (NP) is a rare subtype of neutrophilic dermatosis, a group of neutrophil-rich inflammatory skin disorders that can present in association with myeloid neoplasms. NP is defined by the presence of a neutrophilic infiltrate in the fat lobules of the subcutis in the absence of either infection or vasculitis. We herein describe a 65-year-old woman with a recent diagnosis of myelodysplastic syndrome/myeloproliferative neoplasm overlap syndrome (MDS/MPN) who abruptly developed painful, pruritic nodules consistent with NP. CASE PRESENTATION: A 65-year-old woman with MDS/MPN presented for evaluation of painful and pruritic nodules on her upper and lower extremities. A biopsy revealed a lobular neutrophilic infiltrate in the subcutis without evidence of microorganisms or vasculitis. The patient was diagnosed with NP and treated with oral prednisone. Within 1 month of treatment, she reported complete resolution of the nodules. DISCUSSION: Similar to other neutrophilic dermatoses, NP may arise in association with hematologic malignancies of myeloid origin, such as MDS/MPN. A literature review revealed that most cases of NP associated with MDS occur after the onset of MDS and respond to systemic corticosteroids, not antibiotics. Infection should be ruled out before initiating treatment with systemic steroids. CONCLUSION: Although the mechanism is still unknown, it is important for clinicians to be aware that NP is associated with MDS; thus, hematological malignancies should be investigated upon diagnosis of NP. Once diagnosed, NP is easily treated and has an excellent response to systemic corticosteroids

Utility of T-Cell Immunosequencing in Distinguishing Mycosis Fungoides Progression From Treatment Related Cutaneous Adverse Events

Cutaneous adverse events of both topical and systemic drugs in patients with mycosis fungoides (MF) present a diagnostic challenge as it is often difficult to distinguish drug associated rash from disease progression in the skin. Mogamulizumab and mechlorethamine gel are approved treatments for MF, both of which can cause treatment related cutaneous adverse events. It can often be challenging to distinguish mogamulizumab associated rash (MAR) and mechlorethamine gel associated hypersensitivity dermatitis from MF progression both clinically and histologically. High-throughput sequencing (HTS) of the T-cell receptor (TCR), also known as immunosequencing, can be used to assess T-cell clonality to support a diagnosis of MF. After identification of the malignant TCR clone at baseline, immunosequencing can track the established malignant TCR sequence and its frequency over time with high sensitivity. As a result, immunosequencing clone tracking can aid in distinguishing disease progression from treatment side effects. Here, we present a case series to demonstrate how monitoring of the malignant T-cell frequency by immunosequencing can aid in diagnosis of mogamulizumab and mechlorethamine gel cutaneous adverse events

Recalcitrant Cutaneous Mastocytosis Treated With Genetically Informed Targeted Therapy: A Case Report

Introduction: Mastocytosis, a clonal proliferation of mast cells commonly involving the skin and bone marrow, has a varied clinical presentation ranging from cutaneous lesions to systemic disease. Cutaneous mastocytosis is managed symptomatically, but systemic mastocytosis is treated with targeted therapy against the mutated receptor tyrosine kinase c-KIT, the pathogenic driver of mastocytosis. However, there are no guidelines for the treatment of cutaneous mastocytosis refractory to symptomatic management. We herein report a method to select genetically informed therapy for symptomatic and recalcitrant cutaneous mastocytosis. Case presentation: We performed a mutational analysis of dermal mast cells after enrichment by laser capture in a 23-year-old woman with recalcitrant cutaneous mastocytosis. The analysis revealed a aspartic acid to valine substitution at codon 816 (D816V) mutation in the protein c-KIT. Based on these results, we initiated treatment with the multi-kinase/KIT inhibitor midostaurin, a treatment effective against the D816V c-KIT mutation. After 3 months of treatment, the patient exhibited a reduction in the number and size of cutaneous lesions and reported resolution of pruritus and decreased severity of other mast cell-related symptoms. Discussion: The treatment of mastocytosis relies heavily on whether the disease is limited to the skin or systemic. However, there are no guidelines for cutaneous mastocytosis that does not respond to symptomatic management. In the present report describing a patient with recalcitrant cutaneous mastocytosis, we describe a strategy in which skin mutational analysis is used to guide the selection of targeted therapy. Conclusion: Performing mast cell mutational analyses in the skin provides a means to select targeted therapy for symptomatic and refractory cutaneous mastocytosis

Recalcitrant Subcutaneous Panniculitis-Like T-Cell Lymphoma Responsive to Histone Deacetylase Inhibitor

Subcutaneous panniculitis-like T-cell lymphoma (SPTCL) is a rare subtype of cutaneous T-cell lymphoma that usually presents with tender subcutaneous nodules on the trunk and extremities. Immunosuppressive therapy is considered first-line treatment for SPTCL, while multiagent chemotherapy is used for SPTCL complicated by hemophagocytic lymphohistiocytosis (HLH). Here, we report a 42-year-old Hispanic man that presented with a 5-year history of recurrent painful subcutaneous lesions in the absence of constitutional symptoms, lymphadenopathy, and hepatosplenomegaly. A punch biopsy revealed an atypical lymphoid infiltrate in between subcutaneous adipose lobules. Lymphocytes expressed CD3, CD8, and Beta F-1 and did not express CD4 and CD56. Based on clinical and histologic findings, the patient was diagnosed with SPTCL. In addition, laboratory findings did not demonstrate any evidence of HLH. He was initially started on both prednisone and hydroxychloroquine with no improvement. A trial of cyclosporine and methotrexate yielded no clinical improvement. As the lesions failed to resolve after treatment with multiple immunosuppressive agents, romidepsin, an intravenous histone deacetylase (HDAC) inhibitor, was initiated. After two cycles of romidepsin, the patient achieved complete clinical response. He continues to be in remission 12 months later with monthly maintenance therapy. This case illustrates that romidepsin can be useful as monotherapy for refractory SPTCL without HLH