Polypoid Kaposi Sarcoma Involving the Lower Gastrointestinal Tract: Clinicopathologic Study of 15 Cases.

Gastrointestinal manifestations of Kaposi sarcoma are rare but may cause morbidity. Lower gastrointestinal involvement is particularly rare and lesions may resemble conventional bowel polyps. To study 15 patients who presented with lower gastrointestinal tract Kaposi sarcoma with polypoid architecture. The surgical pathology files of the departments of pathology at multiple institutions were searched for cases of Kaposi sarcoma forming polyps in the lower gastrointestinal tract (jejunum, colon, rectum); 15 cases with such features were identified. Clinicopathologic information was extracted from the medical record and documented by reviewing individual hematoxylin-eosin stained slides. The patients were 13 men and 2 women aged 26-80 years (median = 44 years). Gastrointestinal tract involvement was multifocal in 11 cases and unifocal in 4. The tumors involved the rectum, recto-sigmoid junction, cecum, ascending colon, transverse colon, and descending colon and presented as polypoid lesions measuring 0.2-2.1 cm. Six patients had upper gastrointestinal tract involvement in addition to lower gastrointestinal lesions. Histologically the tumors were characterized in 6 cases by a dense spindle cell proliferation in the lamina propria; however, the remaining cases showed only a subtle fascicular spindle cell proliferation in the lamina propria that did not form an expansile mass. Biopsies of gastrointestinal polyps showing absence of the common features of hyperplastic or adenomatous polyps, particularly in immunocompromised patients, should be carefully examined for the presence of a stromal spindle cell proliferation. Use of immunohistochemical stains, particularly human herpesvirus-8, can help in establishing the correct diagnosis.

Suster DI ，Rastegar S ，Salviato T ，Wang W ，Collins K ，González IA ，Choi WT ，Chen HH ，Gonzalez RS ，McHugh K ，Salomao M ，Charville GW ... -  《-》

Gastrointestinal Kaposi Sarcoma Involving Stomach and Colon: Diagnostic Pitfall for Pathologists with Expression of CD117.

Kaposi sarcoma (KS) is a low-grade vascular tumor caused by human herpes virus type 8 (HHV8). Gastrointestinal involvement of KS is rare and most commonly clinically silent. Gastrointestinal KS may mimic gastrointestinal stromal tumors (GISTs) histologically as the tumor formed by morphologically spindle-shaped cells, which is mostly located in the mucosa and submucosa. In the present study, we describe a case of Kaposi sarcoma that was first diagnosed in the gastrointestinal tract of a 73-year-old female patient who presented to the clinic with nausea and diarrhea. Immunohistochemical staining showed cytoplasmic CD117 expression both in stomach and colon biopsies. Although involvement of KS is rarely seen in the gastrointestinal tract (GIT), the differential diagnosis of low-grade spindle cell lesions without significant pleomorphism, KS should definitely be considered, and it should be known that CD117 positivity is also present in these neoplasms.

Bozdag Z ，Toprak S ，Karadag N ，Akbulut S ... -  《-》

Intestinal perineuriomas: clinicopathologic definition of a new anatomic subset in a series of 10 cases.

Hornick JL ，Fletcher CD 《AMERICAN JOURNAL OF SURGICAL PATHOLOGY》

A clinicopathologic study of 24 cases of systemic mastocytosis involving the gastrointestinal tract and assessment of mucosal mast cell density in irritable bowel syndrome and asymptomatic patients.

Doyle LA ，Sepehr GJ ，Hamilton MJ ，Akin C ，Castells MC ，Hornick JL ... -  《-》

Malakoplakia of the gastrointestinal tract: clinicopathologic analysis of 23 cases.

Lee M ，Ko HM ，Rubino A ，Lee H ，Gill R ，Lagana SM ... -  《Diagnostic Pathology》