Differential diagnosis of anorectal cancer

Anorectal cancer is a malignant tumor that occurs in the anorectal canal. Among digestive tract malignant tumors, its incidence rate is second only to gastric cancer. Rectal cancer is adenocarcinoma, which often occurs at the junction of the upper rectum and the sigmoid colon. Anal canal cancer originates from the skin of the anal canal and is mostly squamous cell carcinoma. Scar tissue, condyloma, hemorrhoids and other lesions in the anus can also induce cancer. The age of onset is mostly after 40 years old, and it is occasionally seen in young people.

1. Clinical manifestations

1. Changes in bowel habits: This is a common early symptom of rectal cancer, characterized by an increase in bowel movements, frequent urge to defecate, but no stool. Sometimes constipation, a feeling of heaviness in the anus

2. Blood in the stool: It is an early symptom of rectal cancer. The blood in the stool is bright red or dark red, not in large amounts, and often contains mucus. As the disease progresses, the stool contains pus, blood, and mucus, and has a special odor.

3. Deformed stool: In the later stage of the disease, due to the narrowing of the intestinal cavity, the stool is less and the shape becomes thinner and flatter, and obstruction signs such as abdominal distension, abdominal pain, and hyperactive bowel sounds appear.

4. Signs of metastasis: If the cancer metastasizes to the liver, there will be liver enlargement and jaundice. If anal canal cancer metastasizes, there may be swollen lymph nodes in the groin. If the sacral nerve plexus is invaded, there will be severe and persistent pain in the rectum or in the rectum, and radiate to the lower abdomen, waist or lower limbs. If the bladder and urethra are invaded, there will be difficulty and pain in urination. At the same time, the patient will have loss of appetite, general weakness, anemia, weight loss and other cachexia symptoms.

5. Examination: Digital examination may reveal hard nodular masses or ulcers in the anus or on the intestinal wall. The intestinal cavity is often narrow, and the finger cot is stained with blood, pus and mucus.

6. Staging: Staging is based on the course of the disease: Stage 1: The lesions are confined to the intestinal wall; Stage 2: The lesions invade the outside of the intestinal wall; Stage 3: Accompanied by lymph node metastasis; Stage 4: Extensive or distant metastasis has occurred.

2. Experimental Medicine

1. Microscopic examination and biopsy: A proctoscopy or sigmoidoscope can not only directly observe the lesion, but also clamp a small piece of tissue for examination to clarify the nature of the disease.

2. Barium enema, stenosis and barium shadow incompleteness can be seen

3. Differential Diagnosis

Early increase in bowel movements or blood in the stool should be differentiated from dysentery, enteritis, internal hemorrhoids, etc. Rectal digital examination is the simplest method of differentiation. When a lump is touched by digital examination, it must be differentiated from an inflammatory lump. Anal canal cancerous ulcers should be differentiated from anal fistulas, condyloma, etc. It is a relatively reliable method for biopsy of tissues.