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WHO Classification of Tumours
Granular cell tumor, NOS
Gallbladder and extrahepatic biliary tract


Granular cell tumour (GCT) is an unusual, benign or malignant neoplasm characterized by the presence of neoplastic large polygonal cells with granular, eosinophilic cytoplasm which contains abundant lysosomes. This tumour was originally thought to originate from muscle cells and was named granular cell myoblastoma. Subsequent studies have suggested a derivation from Schwann cells. GCT can arise in any site of the body, including the posterior pituitary gland, skin, oral cavity, esophagus, stomach, heart, mediastinum, and breast, and usually presents as a solitary mass. A minority of patients have multiple tumours. Women are more often affected than men
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Ordonez NG (1999)
Granular cell tumor: a review and update.
Adv Anat Pathol 6: 186-203


GCT of the gallbladder and extrahepatic biliary tract
Although rare, granular cell tumour is the most commonly diagnosed benign nonepithelial tumour of the gallbladder and extrahepatic biliary tract. In the gallbladder, such tumours are usually incidental microscopic findings, whereas granular cell tumours in the bile ducts can cause symptomatic biliary obstruction that clinically mimics bile duct carcinoma

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te Boekhorst DS, Gerhards MF, van Gulik TM, Gouma DJ (2000)
Granular cell tumor at the hepatic duct confluence mimicking Klatskin tumor. A report of two cases and a review of the literature.
Dig Surg 17: 299-303

Granular cell tumours can be multicentric, involving different visceral sites as well as the skin and peripheral soft tissues. Involvement of the bile ducts often results in a concentric or eccentric mass that variably obliterates the lumen. Histologically, granular cell tumours contain clusters or sheets of polygonal cells with abundant periodic acid–Schiff (PAS)-positive granular cytoplasm and small nuclei. The cells are immunohistochemically positive for S100 protein and α-inhibin

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Murakata LA, Ishak KG (2001)
Expression of inhibin-alpha by granular cell tumors of the gallbladder and extrahepatic bile ducts.
Am J Surg Pathol 25: 1200-3