The most common current staging system is the TNM (for tumors/nodes/metastases) system, though many doctors still use the older Dukes system. The TNM system assigns a number^[31]:

• T - The degree of invasion of the intestinal wall
  • T0 - no evidence of tumor
  • Tis- cancer in situ (tumor present, but no invasion)
  • T1 - invasion through muscularis mucosa into submucosa
  • T2 - invasion through submucosa into the muscularis propria (i.e. proper muscle of the bowel wall)
  • T3 - invasion through the muscularis propria into subserosa but not to any neighbouring organs or tissues
  • T4 - invasion of surrounding structures (e.g. bladder) or with tumour cells on the free external surface of the bowel
• N - the degree of lymphatic node involvement
  • N0 - no lymph nodes involved
  • N1 - one to three nodes involved
  • N2 - four or more nodes involved
• M - the degree of metastasis
  • M0 - no metastasis
  • M1 - metastasis present

Problems

Umbilical granuloma:
Granulation tissue may persist at the base of the umbilicus after cord separation.
The tissue is composed of fibroblasts and capillaries and can grow to more than 1 cm.
Umbilical granulomas must be differentiated from umbilical polyps, which do not respond to silver nitrate cauterization.

Umbilical infections:
Patients with omphalitis may present with purulent umbilical discharge or periumbilical cellulitis.
Although infections may be associated with retained umbilical cord or ectopic tissue,
  in the past, infections were often related to poor hygiene.

Omphalomesenteric remnants:
Persistence of all or portions of the omphalomesenteric duct can result in fistulas, sinus tracts, cysts, congenital bands, and mucosal remnants. Patients with mucosal remnants can present with an umbilical polyp or within an umbilical cyst.

Urachal remnants:
The developing bladder remains connected to the allantois through the urachus. Remnants of this connection include a patent urachus, urachal sinus, and urachal cyst. Umbilical polyps can also be observed in association with a urachal remnant.

Umbilical hernia:
Umbilical hernias result when persistence of a patent umbilical ring occurs. Umbilical hernias may spontaneously close, but many require surgical repair.2

Presentation
Umbilical infections can occur because of an embryologic remnant or poor hygiene. Traditionally, gram-positive organisms, such as Staphylococcus aureus and Streptococcus pyogens, were most commonly identified. Gram-negative and polymicrobial infections are seen today, especially in rapidly progressing cellulitis and necrotizing fasciitis.

Umbilical granulomas appear as 1-mm to 1-cm, pink, friable lesions at the base of the umbilicus. They produce variable amounts of drainage that can irritate the surrounding skin. An umbilical polyp is brighter red than a granuloma and represents retained intestinal or gastric mucosa from the vitelline duct.

The presentation of omphalomesenteric remnants depends on the specific type of defect (see Media file 6). If a communication persists from the terminal ileum to the umbilicus, intestinal contents or stool can be observed leaking from the umbilicus. Prolapse of intestine through an omphalomesenteric fistula can also be observed (see Media file 7). The drainage from a fistula that does not communicate with the ileum varies; it may be clear, bloody, or purulent. Cystic remnants may become infected and manifest with pain and swelling.

The presentation of urachal remnants also varies. Clear drainage from the umbilicus is characteristic of a urachal fistula. Drainage of urine from the umbilicus may suggest bladder outlet obstruction and warrants further investigation. A urachal sinus manifests with drainage that can be clear or purulent. A urachal cyst is usually discovered as a painful mass between the umbilicus and suprapubic area when it becomes infected. Pain and retraction of the umbilicus during urination may suggest a urachal anomaly.

Patients with umbilical hernias present early in life with bulging at the umbilicus. The swelling is most prominent when the infant or child is crying or straining. Umbilical hernias are usually asymptomatic and rarely cause pain. The skin can become severely stretched, which may be alarming to parents and physicians. Parents often mention that the child plays with the redundant skin. Incarceration, strangulation, bowel obstruction, erosion of the overlying skin, and bowel perforation are rare events in infants and small children. The risk of incarceration increases significantly in adults with umbilical hernias.

Media file 1: Cartoon illustrating the developing umbilical cord. (A) Embryonic disk: At this stage, the ventral surface of the fetus is in contact with the yolk sac. (B) The yolk sac narrows as the fetus grows and folds. The intracoelomic yolk sac forms the intestine and communicates with the extracoelomic yolk sac through the vitelline duct. The vitelline duct is also referred to as the omphalomesenteric duct and the yolk stalk. The allantois has begun to grow into the body stalk. (C) The yolk and body stalks fuse to become the umbilical cord.

Media file 6: Omphalomesenteric duct remnants. (A) Meckel diverticulum. Note feeding vessel. (B) Meckel diverticulum attached to posterior surface of anterior abdominal wall by a fibrous cord. (C) Fibrous cord attaching ileum to abdominal wall. (D) Intestinal-umbilical fistula. Intestinal mucosa extends to skin surface. (E) Omphalomesenteric cyst arising in a fibrous cord. The cyst may contain intestinal or gastric mucosa. (F) Umbilical sinus ending in a fibrous cord attaching to the ileum. (G, H) Omphalomesenteric cyst and sinus without intestinal attachments.

Media file 8: Anatomic relationship between the umbilicus and its embryologic attachments.

http://emedicine.medscape.com/article/935618-media 여기서 불펌.