A Case Report of Congenital Transfascial Muscular Hernias Mimicking Skin Nodules – Dynamic Ultrasound Evaluation Uncovering the Chronicles of a Hidden Hernia

Abstract This case report describes a congenital transfascial muscular hernia in a 15-year-old girl who presented with complaints of painless subcutaneous nodules. Initial clinical evaluation revealed multiple painless, symmetrically distributed subcutaneous nodules in both lower limbs, on examination the lesions were reducible and were clinically suspected to be piezogenic nodules. However, dynamic ultrasound evaluation revealed the presence of transfascial muscular hernias, confirming the diagnosis. Muscular hernias are characterized by focal defects of the epimysium through which muscle fibrils herniate upon exertion, most of these are associated with a past trauma and very rarely can be congenital. Close to around 200 cases are reported worldwide among which congenital type is even rarer. This report highlights the importance of using dynamic ultrasound to diagnose congenital type of muscle hernia and to rule out other relevant differential diagnoses in specific subsets of the pediatric population. It also emphasizes the need for clinical suspicion of muscle hernias in patients presenting with subcutaneous nodules, particularly in the lower limbs, and raises awareness among radiologists about this rare condition, in the absence of attributable etiological factors and diagnostic dilemma.