The most common anal sac tumor is apocrine gland adenocarcinoma of the anal sac. This is a tumor that generally involves only one anal sac and can be quite invasive. It can also metastasize to regional lymph nodes within the abdominal cavity. One of the most dangerous features of this particular tumor is the fact that it can secrete a substance that is very structurally similar to a hormone called parathormone. This hormone causes the blood calcium to increase to dangerous levels that can ultimately be lethal.
Excision of these tumors is performed by incising the skin directly over the mass. Using a combination of sharp and blunt dissection as well as electrosurgery, the surrounding tissues are separated from the mass and the associated anal sac. The larger and more invasive the tumor is, the greater the likelihood of potential complications. Once excised, the surgical approach is then closed with multiple layers of suture material.
Potential complications associated with this procedure include but are not limited to hypocalcemia, infection leading to abscessation, fecal incontinence owing to nerve damage and recurrence of the tumor. Hypocalcemia is a potentially dangerous complication as it can lead to severe seizures and death. Hypocalcemia occurs because the secretion of normal parathormone has been suppressed by the persistently high levels of calcium. Assuming the anal sac tumor is removed completely and there is no metastatic disease, there is no longer a source of the parathormone-like hormone causing the calcium to be elevated so the calcium level can drop acutely. In most patients, the calcium level returns to the normal level within a few days. However, it is still a good idea for patients with severe hypercalcemia pre-operatively to spend at least one night in a 24-hour care facility for observation.