A 46-year-old man comes to the physician complaining of intermittent, bloody diarrhea and abdominal pain for the past month. He has lost 12 lbs (5.5 kg) during this period. He was diagnosed with HIV five years ago, but has been noncompliant with his antiretroviral medications. Laboratory results show a CD4 count of 50 cells/µL and viral load of 650,000 copies/mL. Colonoscopy reveals multiple hemorrhagic polypoidal lesions. Biopsy of these lesions reveals spindle cells with surrounding blood vessel proliferation. Which of the following is the most likely cause of this patient's diarrhea?

Question

A 46-year-old man comes to the physician complaining of intermittent, bloody diarrhea and abdominal pain for the past month.  He has lost 12 lbs (5.5 kg) during this period.  He was diagnosed with HIV five years ago, but has been noncompliant with his antiretroviral medications.  Laboratory results show a CD4 count of 50 cells/µL and viral load of 650,000 copies/mL.  Colonoscopy reveals multiple hemorrhagic polypoidal lesions.  Biopsy of these lesions reveals spindle cells with surrounding blood vessel proliferation.  Which of the following is the most likely cause of this patient's diarrhea?

Quizplus · Accepted Answer

11ec160b_3954_9abb_9249_07005fdbdcfb_MD0001_00 Causes of diarrhea in HIV patients include opportunistic and non-opportunistic infections as well as noninfectious causes such as Kaposi's sarcoma (KS). KS is a vascular malignancy caused by human herpesvirus 8 (HHV-8). HIV co-infection substantially increases the risk for developing KS. Skin involvement is characteristic, but extracutaneous spread of KS to the lungs and gastrointestinal tract is also common. KS lesions are easily distinguished endoscopically. They vary from reddish/violet flat maculopapular lesions to raised hemorrhagic nodules or polypoid masses. On biopsy, KS lesions will typically show spindle cells with cytologic atypia, blood vessel proliferation, and extravasated red blood cells with hemosiderin deposition. (Choice A) Adenocarcinoma typically would show dysplastic mucosal cells with a variable degree of gland formation, depending on the differentiation of the tumor. (Choice B) Colonoscopy in cytomegalovirus colitis would show multiple ulcers and mucosal erosions. Biopsy shows characteristic cytomegalic cells with inclusion bodies. (Choice C) Cryptosporidiosis can cause profuse, watery, nonbloody diarrhea, particularly in patients with advanced AIDS (CD4 counts < 180 cells/mm³). Endoscopy shows inflammation but no ulcers. Biopsy shows basophilic clusters on the surface of intestinal mucosal cells. (Choice D) Entamoeba histolytica can cause bloody diarrhea and liver abscess formation. Colonoscopy would show the presence of flask-shaped colonic ulcers. (Choice F) Colonoscopy in ulcerative colitis would show erythematous, friable, granular mucosa and possibly pseudopolyps (isolated areas of regenerative mucosa). An inflammatory infiltrate involving the mucosa and submucosa with crypt abscesses would be seen histologically. Educational objective: Kaposi's sarcoma usually involves the skin and GI tract and is common in HIV patients not on antiretroviral therapy. Endoscopy reveals characteristic lesions, which range from reddish/violet flat maculopapular lesions to raised hemorrhagic nodules or polypoid masses. Biopsy can show spindle cells, neovascularization, and extravasated red blood cells. __________ References: Gastrointestinal malignancies in HIV-infected or immunosuppressed patients: pathologic features and review of the literature. (http://www.ncbi.nlm.nih.gov/pubmed/18163148)

A 46-Year-Old Man Comes to the Physician Complaining of Intermittent