Inearlyacuteappendicitis,subserosalvesselsarecongested,and alllayersofthewall.Theinflammatoryreactiontransforms http://ebooksmedicine.net thenormalglisteningserosaintoadull,granular-appearing,erythematoussurface.Althoughmucosalneutrophilsandfocalsuperficialulcerationoftenarepresent,thesefindingsarenotspecific,anddiagnosisofacuteappendicitisrequiresneutrophilicinfiltrationofthemuscularispropria.Inmoreseverecases,focalabscessesmayformwithinthewall(acute suppurative appendicitis), andthesemayevenprogresstolargeareasofhemorrhagiculcerationandgangrenousnecrosisthatextendtotheserosa,creatingacute gangrenous appendicitis, whichoftenisfollowedbyruptureandsuppurativeperitonitis.
Typically, early acute appendicitis produces periumbilical pain that ultimately localizes to the right lower quadrant, followed by nausea, vomiting, low-grade fever, and a mildly elevated peripheral white blood cell count. A classic physical finding is McBurney’s sign, deep tenderness noted at a location two-thirds of the distance from the umbilicus to the right anterior superior iliac spine (McBurney’s point). These signs and symptoms however, are often absent, creating difficulty in clinical diagnosis.
The most common tumor of the appendix is the carcinoid, or well-differentiated neuroendocrine tumor. It usually is discovered incidentally at the time of surgery or on examination of a resected appendix. This neoplasm most frequently involves the distal tip of the appendix, where it produces a solid bulbous swelling up to 2 to 3 cm in diameter. Although intramural and transmural extension may be evident, nodal metastases are very infrequent, and distant spread is exceptionally rare. Conventional adenomas or non–mucin-producing adenocarcinomas also occur in the appendix and may cause obstruction and enlargement that mimics the changes of acute appendicitis. Mucocele, a dilated appendix filled with mucin, may simply stem from an obstructed appendix containing inspissated mucin or may be a consequence of mucinous cystadenoma or mucinous cystadenocarcinoma. In the latter instance invasion through the appendiceal wall can lead to intraperitoneal seeding and spread. In women, the resulting peritoneal implants may be mistaken for mucinous ovarian tumors. In the most advanced cases, the abdomen fills with tenacious, semisolid mucin, a condition called pseudomyxoma peritonei. This disseminated intraperitoneal disease may be held in check for years by repeated debulking, but ultimately is fatal in most instances.
•Acuteappendicitisismostcommoninchildrenandadolescents.Itisthoughttobeinitiatedbyincreasedintraluminalpressureconsequenttoobstructionoftheappendiceallumen,whichcompromisesvenousoutflow.
Themostcommontumoroftheappendix,thecarcinoid, orwell-differentiated neuroendocrine tumor, ismostoftendiscoveredincidentallyandisalmostalwaysbenign
Theclinicalpresentationofappendicealadenocarcinomacanbeindistinguishablefromthatofacuteappendicitis,althoughtheformertendstopresentinolderpatients.
Hennessey PT, Westra WH, Califano JA: Human papillomavirus and head and neck squamous cell carcinoma: recent evidence and clinical implications, J Dent Res 88:300, 2009. [A discussion of head and neck cancers associated with HPV.]
Leemans CR, Braakhuis BJ, Brakenhoff RH: The molecular biology of head and neck cancer, Nat Rev Cancer 11:9, 2011. [A discussion of the molecular biology of head and neck cancer.]