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 ... -  《-》

Gastrointestinal Kaposi's sarcoma: CD117 expression and the potential for misdiagnosis as gastrointestinal stromal tumour.

Parfitt JR ，Rodriguez-Justo M ，Feakins R ，Novelli MR ... -  《-》

Kaposi sarcoma.

Radu O ，Pantanowitz L 《-》

Histologic Variants of Kaposi Sarcoma in the Gastrointestinal Tract: A Contemporary Multi-institutional Clinicopathologic Analysis of 46 Cases.

Kaposi sarcoma (KS) can pose diagnostic challenges in biopsy specimens. Multiple histologic variants of cutaneous KS have been described; however, the histomorphologic spectrum of gastrointestinal (GI) KS has not been systematically studied. This large series comprehensively evaluated 46 cases of KS involving the GI tract and identified 7 histomorphologic variants, some that have not been previously described. Five of them are inconspicuous but have unique morphologic patterns, including lymphangioma/lymphangiectatic-like (n=17), mucosal hemorrhage/telangiectatic-like (n=17), mucosal inflammation-like (n=15), granulation tissue-like (n=13), and mucosal prolapse-like (n=4) variants. These variants can be easily misdiagnosed or misinterpreted on routine examination if KS is not considered, and if the immunohistochemical stain for human herpesvirus-8 is not performed. The other 2 morphologic variants present as spindle cell proliferations and are the GI stromal tumor-like (n=8) and inflammatory myofibroblastic tumor-like (n=2). These variants raise a broad differential diagnosis of spindle cell tumors of the GI tract and could pose diagnostic challenges. In summary, GI KS lesions exhibit variable, often unconventional histomorphologic patterns. KS should be included in the differential diagnosis even if features of conventional KS are not seen, particularly in limited biopsies in immunocompromised patients, such as those with human immunodeficiency virus infection. Although the clinical significance of these morphologic variants is yet to be determined, they are nonetheless important from a diagnostic standpoint. Misdiagnosis and delay in appropriate management can be avoided by recognizing the morphologic diversity of GI KS and appropriately utilizing the human herpesvirus-8 immunohistochemical stain.

Zheng W ，Obeng RC ，Graham RP ，Lui S ，Cheng J ，Alexiev BA ，Quigley B ，Krasinskas A ，Yang GY ，Escobar D ，Liu X ，Navale P ，Reid MD ，Westerhoff M ，Xue Y ... -  《-》

Upper gastrointestinal Kaposi's sarcoma in HIV-infected patients: ten years of endoscopy observation at a single Brazilian center.

Kaposi's sarcoma (KS) is the most common neoplasm among HIV-infected individuals. The frequency of involvement of KS in the gastrointestinal (GI) tract and the associated epidemiological, immune, endoscopic, and histopathological features in HIV-infected patients, were evaluated in this study. A review of the medical and endoscopy reports of 1428 HIV-infected patients, who had undergone upper GI endoscopy at the Endoscopy Service, Clinical Hospital, Faculty of Medicine of Ribeirão Preto between January 1999 and June 2009, was performed. Clinical, epidemiological, immunological, endoscopic, and histological data were collected. Twenty-seven (1.9%) patients were diagnosed with GI KS. Patients were predominantly male (81.5%). Sexual activity was the main route of HIV transmission (81.5%). Cutaneous involvement was noted in 21 patients (78%). Fifteen patients (55%) received highly active antiretroviral therapy for a mean duration of 12.6 weeks (range 2-52 weeks) before endoscopy. GI lesions were mainly found in the stomach (55%). Analysis of the immunohistochemical methods HHV8 LNA-1, CD31, and CD34 for the diagnosis of gastric KS indicated high agreement (kappa=0.63, 95% confidence interval 0.32-0.94). There was no relationship between CD4 levels (p=0.34) or HIV viral load (p=0.99) and HHV8 LNA-1 positivity in gastric KS. GI KS is an infrequent finding in patients with HIV infection. Among those with GI KS, 80% had concomitant skin lesions. Immunohistochemical methods for CD31, CD34, and LNA-1 were important tools in the diagnostic assessment of lesions suggestive of KS in the GI tract. Further studies are required to confirm these data, and the need for routine endoscopic investigation of the GI tract in HIV-infected patients with cutaneous KS should be assessed.

Rezende RE ，Kahwage RL ，da Costa TV ，Machado AA ，Brunaldi MO ，Kemp R ，Módena JL ... -  《-》