BI16 Double trouble: accelerated and aggressive skin cancer risk in solid organ transplant recipients with haematological (pre)malignancies

Abstract

Both solid organ transplant recipients (SOTRs) and patients with haematological malignancies such as chronic lymphocytic leukaemia and myeloma have a well-recognized increased risk of skin cancer. However, skin cancer risk in SOTRs with haematological (pre)malignancies remains unexplored. We describe two SOTRs with smouldering multiple myeloma (SMM) and aggressive skin cancers. A 74-year-old White man had a kidney transplant in 1985 and was diagnosed with SMM in 2013. His first squamous cell carcinoma (SCC) developed within 2 years, and by 2025, 11 had been excised with increasingly high-risk histology. Azathioprine was switched to mycophenolate mofetil, acitretin was started and intensive topical chemoprevention treatments were deployed. In October 2025 a rapidly growing, asymptomatic, purple nodule on the right forehead was excised within 14 days of appearance and confirmed as Merkel cell carcinoma. Sentinel node biopsy was positive and positron emission tomography–computed tomography demonstrated metastases to parotid and cervical lymph nodes. He is currently undergoing postoperative radiotherapy, but his prognosis is poor and avelumab immunotherapy is being considered. A 63-year-old White man with two previous kidney transplants (2010 and 2018) was diagnosed with SMM in 2020. He developed multiple SCCs from 2020, which became increasingly high risk, despite modification of immunosuppression and systemic and topical chemoprevention. In September 2025 two simultaneous high-risk PT3 SCCs were excised. He is undergoing postoperative adjuvant radiotherapy. In both cases, the onset of SMM was followed by accelerated development of increasingly aggressive skin cancers. SMM is a myeloma premalignancy not usually requiring myeloma-directed therapy. Nonetheless, abnormal plasma-cell clones are associated with altered immune surveillance. As SOTRs are increasingly transplanted at older ages and live longer, the coexistence of post-transplant (and pretransplant) haematological malignancy is rising. Our cases highlight the potentially increased risk of aggressive skin malignancy in this specific SOTR cohort and the need for heightened awareness and intensive surveillance. The extent of this risk requires further evaluation currently underway at our centre.