Colon
Mesenchymal tumors
Kaposi sarcoma
Author: Raul S. Gonzalez, M.D.
Last author update: 4 March 2021
Last staff update: 3 May 2022
Copyright: 2003-2024, PathologyOutlines.com, Inc.
PubMed Search: Kaposi sarcoma[TIAB] colon
Table of Contents
Definition / general | Essential features | Epidemiology | Etiology | Clinical features | Prognostic factors | Case reports | Treatment | Clinical images | Gross description | Microscopic (histologic) description | Microscopic (histologic) images | Positive stains | Negative stains | Sample pathology report | Differential diagnosis | Board review style question #1 | Board review style answer #1Cite this page: Gonzalez RS. Kaposi sarcoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/colontumorkaposi.html. Accessed April 16th, 2024.
Definition / general
- Vascular malignancy caused by human herpes virus 8 (see topic in Soft tissue chapter)
Essential features
- Vascular malignancy most often seen in AIDS patients with HHV8 infection
- Rare in gastrointestinal tract
Epidemiology
- Most common gastrointestinal malignancy attributable to AIDS (Am J Gastroenterol 1991;86:715)
- Currently rare; incidence decreased from use of HAART for AIDS treatment
Etiology
- HHV8 infection
Clinical features
- Usually no clinical sequelae (Gastroenterology 1985;89:102)
- Rarely causes diarrhea, protein losing enteropathy or abdominal pain
Prognostic factors
- Degree of immunosuppression influences prognosis (Scand J Gastroenterol 1991;26:1007)
Case reports
- 77 year old woman with extensive colonic disease that resolved after chemotherapy (J Cancer Res Ther 2012;8:112)
- 87 year old man with coexisting colon cancer (Acta Dermatovenerol Alp Panonica Adriat 2011;20:83)
Treatment
- Chemotherapy and radiation preferred over surgery
Clinical images
Images hosted on other servers:
Kaposi sarcoma
Gross description
- Reddish brown to purple macules or polyps, typically 0.5 - 1.5 cm
Microscopic (histologic) description
- Lamina propria based lesion composed of spindle cells with mild to moderate atypia, arranged in vague fascicles and separated by slit-like vessels
- Extravasated red blood cells common
- PAS positive, diastase resistant hyaline globules sometimes seen
Microscopic (histologic) images
Contributed by Raul S. Gonzalez, M.D.
H&E, intermediate power
H&E, high power
Images hosted on other servers:
Low power
High power
CD34
Negative stains
Sample pathology report
- Rectum, mass, biopsy:
- Vascular proliferation most consistent with Kaposi sarcoma (see comment)
- Comment: An immunostain for HHV8 is positive in the lesional cells.
Differential diagnosis
- Angiosarcoma:
- Negative for HHV8; often epithelioid in gastrointestinal tract
- Gastrointestinal stromal tumor:
- Melanoma:
- Positive for S100
Board review style question #1
Which of the following is considered a risk factor for developing Kaposi sarcoma?
- Female sex
- HIV / AIDS
- Prior bariatric surgery
- Young age
Board review style answer #1
