Abdominal Sebaceous Cysts are noncancerous lumps that can develop in the abdominal area due to a blocked sebaceous gland. They are usually soft, yellowish lumps that can range in size from a few centimeters to several inches in diameter. Symptoms of abdominal sebaceous cyst may include pain, swelling, redness, or tenderness around the lump. In some cases, the cyst may become infected and cause further complications.