Editing Mesenteric disease


== '''Mesenteric cysts''' ==

* Pathophysiology
** Most commonly mesothelial cysts
** Duplication cyst - see separate topic
** 60% small bowel mesentery, 40% colon mesentery
* Presentation
** Abdominal pain, fever, vomiting
* Management
** Enucleation generally effective, as local vasculature is not adherent to cyst wall
** Internal drainage into the peritoneal cavity has been successfully used to very large cysts
** Aspiration alone has a high rate of recurrence
** Need to examine the cyst wall carefully and biopsy it if you aren't going to excise it

== '''Acute mesenteric lymphadenitis''' ==

* A syndrome of acute right lower quadrant abdominal pain associated with mesenteric lymph node enlargement and a normal appendix
* Epidemiology
** Most common in children and young adults
** Male and female equally
* Pathophysiology
** Numerous implicated causative organisms
*** Viral
*** Bacterial
**** Yersinia enterocolitica
*** Parasitic
*** Fungal
* Presentation
** Often acute periumbilical pain which shifts to RIF
** Can see RIF guarding and peritonism
** Nausea, vomiting, diarrhoea, and anorexia may be present
** WCC may be elevated
** Fever may be present
** Usually differentiated from appendicitis with ultrasound
* Management
** Self-limiting

== '''Sclerosing mesenteritis aka mesenteric panniculitis''' ==

* ''A rare, non-neoplastic inflammatory and fibrotic condition affecting the small bowel mesentery''

* Epidemiology
** Twice as common in men
** Usually 40-50yo
* Aetiologies (proposed)
** Abdominal surgery or trauma
** Autoimmunity
** Paraneoplastic syndrome
** Ischaemia and infection
* Pathophysiology
** Most often involves the root of the small bowel mesentery and frequently encompasses the mesenteric vessels
** Retracts and shortens the mesentery of the small bowel without directly involving small bowel. Can lead to mesenteric venous and lymphatic obstructions.
** Gross appearance - marked thickening of the mesentery of the small intestine with irregular areas of discolouration suggesting fat necrosis. There may be multiple discrete nodules on the mesentery or it may be a single matted mass.
** Histologically - sclerosing fibrosis, fat necrosis with lipid-laden macrophages, chronic inflammation with germinal centres, and focal calcification
*** Early - develops with a loose myxomatous appearance that progresses to chronic inflammation and dense sclerosis
* Presentation
** Mostly asymptomatic, found incidentally on imaging
** Can lead to abdominal pain or symptoms of obstruction
** Abdominal mass palpable in >50% of patients
** ESR and CRP may be elevated (80%)
* Imaging
** CT findings:
*** '''<nowiki/>'Misty mesentery''''
*** A fatty mass arising from the base of the mesentery, with well-delineated margins separating it from normal mesentery - 'tumoural pseudocapsule'
*** Normal adipose tissue surrounding mesenteric vessels - 'fat ring sign'
*** Normal mesenteric vessels coursing through the fatty mass, without evidence of vascular involvement or deviation
*** An intra-abdominal mass that displaces adjacent bowel loops without invading them
* Differential diagnosis
** Any condition that alters the density of mesenteric fat
** Inflammatory
** Neoplastic
*** NHL - look for retroperitoneal lymphadenopathy, splenomegaly, and lack of tumoural calcification. Less likely if fat ring is present.
*** Neuroendocrine tumours with desmoplastic reactions - look for focal bowel/hepatic lesions
*** Peritoneal carcinomatosis
*** Desmoid tumours - paucity of inflammation
*** Peritoneal carcinomatosis
*** Mesenteric and retroperitoneal sarcomas
** Fluid (oedema, blood, lymph)
** Fibrosis
* Diagnosis
** Surgical biopsy is generally necessary for definitive diagnosis
* Management
** Mostly improve spontaneously
** Corticosteroids and anti-inflammatories have been found to improve symptoms and radiologic findings
** Often repeat CT in 6/12 if no signs of the above underlying diseases
** Consider biopsy if there is anything to biopsy
** Operative management 
*** Diagnostic confusion
*** SBO

[[Category:Small bowel]]