Omental caking describes a change in the omentum, a soft, fatty, apron-like layer of tissue that drapes over abdominal organs like the stomach and intestines. The term “caking” refers to this tissue becoming abnormally thick, dense, and hardened. This transformation happens when the omentum is infiltrated by abnormal cells or substances, causing it to lose its pliable texture.
This hardening and thickening is what doctors identify on medical scans. Omental caking is not a disease in itself but a sign of an underlying medical condition within the peritoneal cavity, the space that contains the abdominal organs.
The Anatomy of the Omentum
The omentum is a large sheet of fatty tissue with two main parts: the greater omentum and the lesser omentum. The greater omentum hangs down from the stomach and drapes over the intestines, while the lesser omentum connects the stomach and the first part of the small intestine to the liver. This structure is rich with blood vessels and lymphatic channels, making it a dynamic tissue.
One of the omentum’s primary functions is to store fat, providing energy and insulation for the abdominal organs. It also acts as a protective cushion, shielding the intestines from injury. The omentum is a center for immune activity in the abdomen, containing clusters of immune cells called “milky spots” that monitor the environment.
This immune function has led to the omentum being described as the “policeman of the abdomen.” It is mobile and can migrate toward an area of infection, inflammation, or injury. Upon reaching a problem site, it can adhere to the affected organ, walling it off to prevent the spread of infection or inflammation throughout the abdominal cavity.
Underlying Causes of Omental Caking
The development of omental caking is most frequently linked to the spread of cancer from another organ, a process known as metastasis. This condition is a common finding in advanced cancers of the ovary, stomach (gastric), colon and rectum (colorectal), and pancreas. The connection is particularly strong with ovarian cancer, where omental caking is a characteristic sign of the disease’s progression.
The mechanism behind this spread is often peritoneal seeding. In this process, cancer cells detach from the primary tumor and are shed into the peritoneal fluid, the lubricating fluid within the abdominal cavity. This fluid circulates throughout the abdomen, carrying the malignant cells, which can then implant and grow on the omentum’s fertile surface.
Once implanted on the omentum, the cancer cells multiply, forming new tumors or nodules. As these nodules grow and merge, they cause the omentum to become progressively thicker and more rigid. This extensive tumor growth is what transforms the soft, fatty tissue into a hard, plaque-like mass.
While cancer is the predominant cause, omental caking can occasionally arise from non-cancerous conditions, such as severe inflammatory processes and certain infections. Tuberculous (TB) peritonitis, an infection of the abdominal lining, is a well-documented non-malignant cause, though it is less common in developed countries. In these instances, the thickening is due to chronic inflammation and the formation of granulomatous tissue.
Associated Symptoms and Diagnosis
The physical changes in the omentum lead to a variety of symptoms. One of the most common signs is abdominal bloating or swelling, known as distension. This is often caused by the buildup of fluid in the abdomen (a condition called ascites) as the diseased omentum can no longer regulate fluid balance. The solid mass of the caked omentum also contributes to this fullness and increased abdominal girth.
Patients may also experience abdominal pain or a vague sense of discomfort. Another symptom is early satiety, the feeling of getting full after eating only a small amount of food. This happens because the hardened omental mass can press on the stomach and intestines, reducing their capacity and leading to unintentional weight loss. Changes in bowel habits, such as constipation, may also occur.
Diagnosing omental caking begins when a patient presents with these symptoms, prompting medical imaging. A computed tomography (CT) scan of the abdomen and pelvis is the most common imaging tool used to identify the condition. On a CT scan, omental caking appears as a dense, nodular soft-tissue mass, clearly different from normal abdominal fat.
While a CT scan can identify omental caking, a definitive diagnosis of the cause requires a biopsy. During a biopsy, a small sample of the thickened omental tissue is removed, often using a needle guided by CT or ultrasound. This tissue sample is then examined by a pathologist to confirm the presence of cancer cells or identify signs of infection, establishing the underlying cause.
Medical Management and Treatment
The discovery of omental caking directs medical attention to the underlying disease that caused it. Treatment strategies are not aimed at the omentum directly but at the primary condition, most often an advanced cancer. The management plan depends on the type of primary cancer, its extent, and the patient’s overall health.
Systemic therapies are a foundational component of treatment. These include chemotherapy, which uses drugs to kill fast-growing cancer cells, and targeted therapy, which uses medications that attack specific characteristics of cancer cells. These treatments circulate through the bloodstream to reach cancer cells in the omentum and other sites of metastasis, helping to shrink tumors and control the disease.
Surgery is another intervention, particularly for ovarian cancer. An omentectomy, the surgical removal of the omentum, is often part of a larger cytoreductive or “debulking” surgery. The goal is to remove as much visible tumor as possible from the abdominal cavity, which helps relieve symptoms like abdominal pressure and early satiety.
In situations where the disease is advanced, palliative care becomes a focus. Palliative measures are aimed at improving quality of life by managing symptoms like pain, bloating from ascites, and nausea. This can involve procedures to drain abdominal fluid (paracentesis) and medications to control pain, prioritizing patient comfort.