benign mesenchymal polyps with focus on the colon...2016/05/18 · •benign gastrointestinal...
TRANSCRIPT
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Benign Mesenchymal Polyps with Focus on the Colon
...including the BUMP
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General Remarks
• Usually asymptomatic lesions
• Incidental finding in (screening) coloscopy
• Usually solitary and small
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Perineurioma
• Initially named ‚benign fibroblastic polyp‘
• Mucosa, sometimes involving submucosa
• Rectosigmoid colon
• Positive for perineurial markers
– EMA, GLUT-1 and claudin-1
• Negative for
– Vimentin, CK, SMA, Desmin, CD34, S100
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Am J Surg Pathol 2010
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Schwann Cell Hamartoma
• Initially called ‚mucosal neuroma‘
• ‚Schwannoma‘ and ‚Schwann Cell Hamartoma‘ considered synonymous according to WHO
• No association to genetic syndromes!
– i.e. NF1 and MEN2B
• S100 diffusely positive
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S100
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Ganglioneuroma
• Usually sporadic and solitary
– Syndromic association unlikely
• Located in mucosa
• Can occur in genetic polyposis syndrome
– MEN2B, NF1 and FAP
– Diffusely involves the bowel wall
• S100 diffusely positive
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Granular Cell Tumor
• Mostly esophagus and right colon
– Colon: sumucosa, rarely extending into base of mucosa
– Esophagus: subepithelial, pseudoepithelial hyperplasia
• PAS positive, diastase resistant
• S100 positive (also inhibin and calretinin)
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Leiomyoma
• Usually rectum and sigmoid colon
• Lamina muscularis mucosae
– esophagus: Tunica muscularis propria!
• Rarely symblastic
• Positive for SMA and desmin
• Negative for EMA, S100, CK and CD34
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Finally...the BUMP
• Benign unclassified mesenchymal polyp
• ‚wastebasket‘
• ‘In our institution*, we diagnose these unnamed mesenchymal polyps simply as benign unclassified mucosal polyps or BUMPs’
*Department of Pathology, University of Michigan Hospital, Ann Arbor
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‚Characteristics‘
• Spindled cells , adipocytes, blood vessels of all shapes and sizes
• Any type of stroma, including collagenous, elastic, and myxoid
• IHC specific for types of cells that make up their composition
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Histopathology, 2015
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• Benign Gastrointestinal Mesenchymal BUMPS Arch Pathol Lab Med. 2011;135:1311–1319
• Polypoid stromal lesions of the intestines Histopathology 2015, 66, 88–101
• Benign Serrated Colorectal Fibroblastic Polyps/Intramucosal Perineuriomas Are True Mixed Epithelial-stromal Polyps (Hybrid Hyperplastic Polyp/Mucosal Perineurioma) With Frequent BRAF Mutations
Am J Surg Pathol 2010;34:1663–1671
References