MedGen

A rare histiocytic tumor characterized by a malignant proliferation of cells showing morphological and immunophenotypic features of mature tissue histiocytes. Most cases occur in extranodal sites, most commonly the intestinal tract, skin, and soft tissue. Patients may present with a solitary mass, lymphadenopathy, a skin rash or numerous tumors on the trunk and extremities, lytic bone lesions, hepatosplenomegaly with pancytopenia, intestinal obstruction, and/or systemic symptoms. The neoplasm is aggressive with typically poor therapy response. [from ORDO]

A sporadic or less frequently familial neoplasm that arises from the glandular epithelium of the gastrointestinal tract and liver. In the gastrointestinal tract, it manifests as a polypoid or flat circumscribed lesion. Morphologically, it is characterized by a proliferation of neoplastic glandular cells and is associated with dysplasia. Based on the growth pattern, it may be classified as tubular, villous, or tubulovillous. The dysplasia is classified as mild, moderate, or severe. The frequency of malignant transformation depends on the size of the lesion and the degree of dysplasia. Larger gastrointestinal tract adenomas with severe dysplastic changes carry a higher risk of progression to invasive adenocarcinoma. Gastrointestinal adenomas may present as solitary or multifocal lesions. In the liver, it arises from the hepatocytes. Grossly, it appears as a soft, round mass. Morphologically, the neoplastic cells resemble normal hepatocytes. [from NCI]

A mantle cell lymphoma that affects the stomach. It may arise as a solitary mass or it may be a component of multifocal lymphomatous polyposis of the gastrointestinal tract. It usually has an aggressive clinical course. [from NCI]

Juvenile xanthogranuloma is the most common type of non-Langerhans cell histiocytosis (see this term) characterized by the occurrence of one or more reddish or yellowish self-limiting and benign papules or nodules of several millimeters in diameter, usually appearing on the head and neck (but sometimes on the extremities and trunk) during the first year of life (or rarely in adulthood) and usually regressing spontaneously. Extracutaneous involvement has also been reported, involving most commonly the eye (uveal tract) but with other locations including the central nervous system, lung, liver, bones and endocrine glands, and may be associated with considerable morbidity. [from ORDO]