Health

What are the cells of origin and the immunohistochemical profile of Paget disease?  The Paget cells (intraepithelial large cells with pale pink cytoplasm and large nuclei) are believed to be of apocrine lineage and show immunoreactivity with low-molecular-weight keratins Cam 5.2, CK7, and carcinoembryonic antigen. Mucin stain may be positive. The differential diagnosis includes pagetoid …

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How is anal intraepithelial neoplasia (AIN) graded and what is the risk of progression to squamous cell carcinoma (SCC)?  AIN is graded as low grade (AIN I or mild dysplasia) and high grade (encompasses AIN II and AIN III or moderate and severe dysplasia or carcinoma in situ, respectively). The term Bowen disease is used for lesions …

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The typical findings of Hirschsprung’s disease include absence of ganglion cells. What other stain can help support the diagnosis, and what is the ideal site of biopsy?  Acetylcholinesterase stain highlights the proliferation of thickened nerve fibers in the lamina propria and muscularis mucosae. This stain is done on the frozen tissue. So, ideally, two biopsy …

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What are the histologic types of mixed endocrine exocrine neoplasms?  These include goblet cell carcinoid, tubular carcinoid, and mixed carcinoid-adenocarcinoma. Mixed carcinoid-adenocarcinoma carries the worst prognosis.

What is the incidence of carcinoid tumors in appendectomy specimens (performed for appendicitis)?  Appendiceal carcinoid has been reported in 0.3% to 0.9% of appendectomy specimens. It is the most common appendiceal neoplasm. The functioning tumors are commonly serotonin-producing neoplasms. The risk factors for malignancy include size greater than 2 cm and invasion of mesoappendix.

Mucinous lesions of the appendix Mucocele is a cystically dilated appendiceal lumen containing mucus. It can be nonneoplastic or neoplastic. Any obstruction of the lumen can give rise to mucocele. In low-grade mucinous adenocarcinomas, with pseudomyxoma peritonei, the mucin/tumor cells dissect through the wall of the appendix into the peritoneum. Most cases of synchronous tumors in the ovary …

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Differential diagnosis of stromal tumors in colon Gastrointestinal stromal tumors (GISTs) in the GI tract most commonly occur in the stomach (50%), followed by the small bowel (25%), colon and rectum (10%), and, least commonly, esophagus (5%). Histologically, these can be spindled or epitheloid and show strong reactivity with CD117 (95%), and 60% to 70% show …

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