To describe an association between probable germline variants in genes associated with immune dysfunction and cancer predisposition, and recurrent Parsonage-Turner syndrome (PTS) in a patient with three histologically distinct lymphomas. 

PTS is an autoimmune-mediated brachial plexopathy which typically presents with acute shoulder pain, weakness, sensory changes, and muscle atrophy. Multiple relapses have been seen with hereditary forms, half of which are associated with germline SEPTIN9 alterations.  

Informed consent was obtained from the patient for the publication of this case report.

A  65-year-old man with a past medical history of mantle cell lymphoma diagnosed in 2018 in complete remission (CR), diffuse large B cell lymphoma in 2023 in CR, and peripheral T cell lymphoma (PTCL) status post autologous stem cell transplant (ASCT) 12/2025 with four episodes of PTS. The first episode occurred following orthopedic surgery at age 21. The latter two occurred in his late 20s and 40s triggered by upper respiratory infections. He developed another episode of PTS five weeks following his ASCT for PTCL. Magnetic resonance imaging and electrodiagnostic testing were consistent with PTS rather than neurolymphomatosis. SEPTIN9 genetic testing was negative. Serum paraneoplastic panel was negative. Family history was notable for lymphoma, breast cancer, and rheumatoid arthritis. There may be an underlying genetic susceptibility for recurrent PTS given pertinent personal and family history of cancer and autoimmune disorders. A blood-based next generation sequencing assay identified several germline variants that could be involved in immune dysregulation including ATM (p.L1420F) and TET2 (p.G355D). Additional genetic testing with Invitae evaluating gene variants associated with genetic disorders identified BLM c.934T>G (p.Ser312Ala). 

This case raises the possibility of a shared genetic susceptibility underlying the patient’s lymphomas and PTS, especially given then initial episodes of PTS predated the cancer diagnosis. Probable germline origins in ATM and TET2 are under evaluation with dedicated germline testing.