Calcineurin inhibitor-induced pain syndrome: an uncommon side effect of immunosuppressive therapy after allogeneic hematopoietic stem cell transplant. a case report and review of the literature.

Calcineurin inhibitor-induced pain syndrome (CIPS) is a rare complication of immunosuppressive therapy, predominantly described in solid organ transplantation and only occasionally after allogeneic hematopoietic stem cell transplantation (allo-HSCT). We report an atypical early presentation of CIPS in a 57-year-old woman with adverse-risk acute myeloid leukemia undergoing matched sibling donor allo-HSCT. GVHD prophylaxis included ciclosporin, methotrexate, and antithymocyte globulin. On day + 2, the patient developed severe, stabbing back pain refractory to opioids and partially responsive to pregabalin. Extensive cardiologic, neurologic, radiologic, and laboratory workup was negative except for mild alkaline phosphatase elevation; ciclosporin levels were therapeutic. After exclusion of alternative etiologies, CIPS was suspected (Naranjo score 7). Pain resolved rapidly following ciclosporin discontinuation and steroid introduction, with no recurrence during subsequent tacrolimus therapy.