{"doi":"10.1001/jamadermatol.2025.4688","title":"JAK2 Fusions in Adult Patients With Mycosis Fungoides and CD30 Lymphoproliferative Disorders","abstract":"Importance: Janus kinase 2 (JAK2) gene fusions characterize cytotoxic cutaneous T-cell lymphoma (CTCL) including primary cutaneous CD8-positive aggressive epidermotropic cytotoxic T-cell lymphoma (pcAETCL). The identification of these fusions is rarely reported in indolent CTCL. Objective: To characterize patients with CTCL to better understand the diagnostic, prognostic, and therapeutic significance of this molecular alteration in CTCL. Design, Setting, and Participants: A retrospective case series of patients with CTCL with JAK2 fusions identified between the years 2000 and 2025. Fusions were identified by a custom RNA sequencing panel and by a targeted hybrid-capture-based next-generation DNA sequencing-based panel. The study included a single referral cancer center in the US. Results: Overall, 43 patients (12 female [27.9%] and 31 male individuals [72.1%]; median [range] age, 45 [16-65] years) with CTCL who were found to have JAK2 gene fusions during evaluation and follow-up were included. Thirty-eight of the 43 identified patients (88.4%) with fusions of JAK2 and 10 different gene partners (most frequently ATXN2L, CAPRIN1, and PCM1) had mycosis fungoides (MF), CD30-positive lymphoproliferative disorders (LPD), or overlap presentations, whereas 4 pcAETCL and 1 peripheral T-cell lymphoma not otherwise specified were identified. Secondary genetic events included mutations of epigenetic and transcriptional regulators. Neither mutational burden, type, or fusion partner distinguished cases with early-stage or aggressive CTCL. Conclusions and Relevance: This case series found that JAK2 fusions were seen in aggressive cytotoxic CTCL as well as in T-cell lymphomas with more indolent behavior, possibly representing a precursor lesion to aggressive evolution with age and comorbidities. The prominence of these fusions supports a potentially larger role for JAK2 targeting in patients with early-stage MF, CD30-positive LPD, or overlap presentations.","journal":"JAMA Dermatology","year":2025,"id":535551,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":2,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9668,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2025-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":658885,"name":"Viviane Liao","orcid":"0000-0001-9355-1298","position":1,"is_corresponding":false},{"id":1234959,"name":"Leore Lavin","orcid":"0000-0002-2793-5282","position":2,"is_corresponding":false},{"id":658726,"name":"Haiming Tang","orcid":"0000-0001-7058-349X","position":3,"is_corresponding":false},{"id":1419633,"name":"Mi-Sook Do","orcid":null,"position":4,"is_corresponding":false},{"id":227790,"name":"Andrea P. Moy","orcid":"0000-0001-5431-6682","position":5,"is_corresponding":false},{"id":513120,"name":"César A. Virgen","orcid":"0000-0001-5273-7360","position":6,"is_corresponding":false},{"id":1419634,"name":"Liam Donnelly","orcid":null,"position":7,"is_corresponding":false},{"id":723197,"name":"Melissa Pulitzer","orcid":"0000-0002-0606-9186","position":8,"is_corresponding":false},{"id":1063749,"name":"Shamir Geller","orcid":"0000-0003-1206-1057","position":0,"is_corresponding":true}],"reference_count":12,"raw_metadata":null,"created_at":"2026-07-19T02:51:56.297114Z","pmid":"41296329","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}