Background: Cystic hygromas are primarily found in the cervicofacial, thoracic, and abdominal regions, with limited occurrences in other areas. Despite existing literature on this condition, comprehensive descriptions and MRI findings of cystic hygromas in the extremities are rare. Aim: This case report aims to present a unique instance of a cystic hygroma in the left thigh. The objective is to provide detailed insights into the characteristics of this atypical presentation. Case Presentation: The case involves a 2-year-10 month-old girl with a cystic hygroma in her left thigh. The report includes a comprehensive description of the lesion's clinical features and diagnostic evaluation, emphasizing the MRI findings to enhance understanding of this rare occurrence. Conclusion: This case report highlights the rarity of cystic hygromas outside the cervicofacial, thoracic, and abdominal regions, explicitly focusing on the occurrence in the left thigh. By presenting detailed insights into the clinical features, MRI findings, histopathological findings, and the surgical approach employed, this report contributes to the existing knowledge on this condition in atypical locations and informs future treatment strategies.