Pathology of the anus
■ Inflammatory processes and non-neoplastic lesions A number of inflammatory and infectious processes may affect the anal canal; the histologic findings of anal fissures and ulcers, abscesses, and fistulas are…
Pathology of the gallbladder and extrahepatic bile ducts
■ Gallbladder Cholecystitis Clinical features Chronic cholecystitis due to gallstones most frequently results in intermittent right upper quadrant visceral pain that follows eating (so-called biliary colic). Acute cholecystitis typically presents…
Epithelial neoplasms of the colorectum
A large variety of neoplasms may occur in the colorectum, a reflection of the complexity of this organ and its cellular components. This chapter focuses primarily on those neoplasms arising…
Molecular diagnostics in gastrointestinal pathology
Molecular diagnostics is a field of medicine that applies molecular biology techniques to the diagnosis of disease. Molecular diagnostics includes traditional methods such as cytogenetics, as well as encompassing the…
Gastrointestinal lymphoma
The gastrointestinal tract is the most common site of extranodal non-Hodgkin lymphoma. Approximately 10% to 15% of all non-Hodgkin lymphoma primarily involves the gastrointestinal tract. Secondary GI tract involvement is…
Infectious diseases of the colon
When evaluating a colonic biopsy for possible infectious processes, the surgical pathologist must first attempt to differentiate histologic changes suggesting infectious colitis from other inflammatory processes, especially chronic idiopathic inflammatory…
Non-neoplastic and neoplastic disorders of the appendix
■ Fibrous obliteration of the appendiceal lumen (neural hyperplasia) Clinical features There are no specific features as this is typically an incidental finding in about one third of appendices excised…
Idiopathic inflammatory bowel disease
Idiopathic inflammatory bowel diseases include the chronic crypt destructive colitides, chronic ulcerative colitis, and Crohn’s disease. Ulcerative colitis and Crohn’s disease differ in natural history, clinical and pathologic associations, effective…
Inflammatory/descriptive/iatrogenic colitides
■ Collagenous colitis Clinical features Patients with collagenous colitis (CC) present with a history of chronic watery diarrhea. Colonoscopy typically shows normal or near normal mucosa, although there are a…
Gastrointestinal mesenchymal tumors
■ Gastrointestinal stromal tumor Gastrointestinal stromal tumors (GISTs) are soft tissue tumors that either express C-kit/CD117 protein or have C-KIT or platelet-derived growth factor receptor-α ( PDGFRA ) mutations and…
