Encapsulated fat necrosis is a benign entity that has multiple possible conditions in the differential diagnosis. Because of this, the ultrasound and histological studies become highly relevant. We present a 14-year-old boy with this condition who exhibited numerous nodules that were detected after an intentional weight loss of 20kg. The ultrasound and histopathological examinations were necessary to confirm the diagnosis. Even though there is not a clear traumatic record in all cases, trauma constitutes the main hypothesis for its development, by decreasing the blood supply to the adipose tissue lobules and causing subsequent ischemic necrosis. Similar lesions have been described in the omentum and in the breast after surgical procedures or invasive diagnostic tests. In the ultrasound study, at least three presentation patterns have been described, which might match the three histological states, from early fat tissue degeneration to ultimate necrosis and even calcification. It is important to know the clinical characteristics, the ultrasound patterns, and the histological findings of this condition for an accurate diagnosis.