A 69-year-old man developed generalized muscle spasms 9 days after undergoing surgery for a strangulated intestinal obstruction. He subsequently experienced respiratory failure and required mechanical ventilation in the intensive care unit. Tonic spasms were exacerbated by external stimuli, such as sound, and trismus emerged following tracheostomy. The patient was diagnosed as having tetanus, and targeted therapy was initiated, resulting in gradual clinical improvement. Tetanus is a neurotoxic syndrome caused by tetanospasmin, an exotoxin produced by Clostridium tetani, a bacterium commonly found in soil and present in human feces. Although rare, endogenous tetanus can occur following gastrointestinal surgery, likely due to translocation of the organism from the gut. This case highlights the need for clinicians to consider the gastrointestinal tract as a potential source of tetanus in postoperative patients presenting with muscle rigidity or spasms.

Driver mutations in KMT2A-rearranged (KMT2A-r) have been identified in acute myeloid leukemia (AML); however, age-related differences in their frequency and prognostic factors remain unclear. In this study, we report age-specific mutation profiles and outcomes in pediatric patients with KMT2A-r AML. In 239 cases of KMT2A-r AML, infants (<1 year, n = 59) showed a significantly higher event-free survival (EFS) and overall survival (OS) compared with children (≥1 year, n = 180). Conversely, in 538 cases of non-KMT2A-r AML, infants exhibited a significantly lower EFS and OS than children. KMT2A::MLLT4 was only detected in children with KMT2A-r AML and was associated with a poor prognosis. In KMT2A-r AML, mutations in signaling pathway genes, such as KRAS, were frequently detected in infants and children. However, the frequency of non-signaling pathway mutations was significantly higher in children. Moreover, non-signaling pathway mutations had no significant effect on the prognosis in infants and children, whereas KRAS mutations were associated with poor prognosis in both groups. Multivariate analysis identified older age, a high white blood cell count, KMT2A::MLLT4, and KRAS mutations as independent adverse prognostic factors for both EFS and OS. These age-specific mutation profiles suggest distinct disease mechanisms across age groups and may help refine risk stratification and treatment strategies for pediatric KMT2A-r AML.