This lesion was clinically suggested to be as subcutaneous lipoma vs hernia by the surgeon. Asking the patient about any history of trauma, he disclosed a trivial trauma few months ago.

Sonographic findings along with the history of trauma were highly suggestive of traumatic fat necrosis.

Diagnosis was confirmed on CT images (not shown) which showed a focal area of increased fat attenuation in the subcutaneous plane of the anterior abdominal wall at the site of the palpable lump. 

Post-traumatic fat necrosis is a benign condition developing due to necrosis of the subcutaneous fat by traumatic inflammatory process followed by healing by fibrosis with formation of peripheral fibrous capsule encasing the central core of liquid fat. Fibrous capsule may show calcification.