Deltoid muscle hernia: An unusual site of myofascial hernia

Muscle hernias are relatively uncommon, with most cases reported in the leg involving the tibialis anterior muscle. However, hernias can affect other muscles in both the upper and lower limbs. Here, we present the first documented case of nontraumatic deltoid muscle hernia. An 80-year-old woman presented to the outpatient department with soft tissue masses on the lateral aspect of her left shoulder, accompanied by mild activity-related pain. Dynamic ultrasonography was done and revealed two discrete transfascial defects through which herniation of outer fibres of deltoid muscle into the subcutaneous plane was noted which was prominent on abduction, features characteristic of muscle hernia. No further investigations were pursued, and the patient was reassured and advised to limit activities involving the affected muscle. This article underscores the importance of considering muscle hernias in the differential diagnosis of soft tissue masses, even when occurring in atypical locations such as the deltoid muscle, and the importance of ultrasound examination in such cases.