Numb chin syndrome as a presentation for acute myeloid leukemia relapse post-hematopoietic cell transplant: Case report and review of literature.

NCS is defined as reduced or absent sensation in the chin and lower lip within the distribution of the mental or inferior alveolar nerves. Although commonly associated with local trauma, NCS can indicate an underlying malignancy or can be the presenting symptom of cancer recurrence. We describe a 6-year-old female patient with AML and t(8,21) who underwent allogeneic HCT. Five months post-HCT, the patient presented with right-sided facial pain and numbness in her chin and lower lip consistent with NCS. Two weeks later, the patient had bone marrow relapse indicating AML recurrence. Although NCS remains a rare diagnosis especially in children, in the context of leukemia, it usually indicates an advanced disease or could be a sign of recurrence, and is commonly associated with grim prognosis. Further research is needed to study the link between NCS and specific cytogenetic abnormalities.