HIV/AIDS

Abdominal opportunistic infections and neoplasms resulting from HIV/AIDS-related immunodeficiency

Liver and spleen

• Small hypodense nodules may be microabscesses

• Larger hypodense lesions might be infectious, but AIDS-related lymphoma should be considered

• Pneumocystis may result in tiny calcifications

Biliary tree

• Cholangitis or acalculous cholecystitis caused by opportunistic infections

Stomach, small bowel, and large bowel

• Wall thickening raises concern for opportunistic infection, which can involve any segment of GI tract

• Mural thickening of esophagus suggests esophagitis, often due to candidiasis, CMV, or HSV

• Proctitis in homosexual men related to sexual activity may be due to Neisseria gonorrhoeae , Chlamydia , or HSV

• Focal mass-like wall thickening in GI tract should raise concern for malignancy (lymphoma, Kaposi sarcoma)

Lymph nodes

• Mild generalized lymphadenopathy (usually < 1.5 cm) is typically reactive and may be 1st clue to HIV infection

• More significant adenopathy (> 1.5 cm) suggests opportunistic infection or AIDS-related lymphoma

• AIDS-related lymphoma may be associated with discrete lesions in liver/spleen or focal mass in GI tract

Kidneys

• Bilateral large kidneys (↑ echogenicity on US) with urothelial thickening due to HIV nephropathy

Infections more common in HIV patients even with CD4 > 200, although risk ↑ substantially with lower CD4 counts

Incidence of AIDS-defining malignancies (AIDS-related non-Hodgkin lymphoma, Kaposi sarcoma) has dramatically ↓ with effective antiretroviral therapy

Acquired immune deficiency syndrome (AIDS)

Human immunodeficiency virus (HIV)

Abdominal opportunistic infections and neoplasms resulting from HIV/AIDS-related immunodeficiency

Best diagnostic clue

• Multiple focal hepatic or splenic lesions in patient with known AIDS

• Necrotic mesenteric nodes in patient with AIDS

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    Mycobacterium avium-intracellulare (MAI)

Location

• Can affect visceral organs, GI tract, genitourinary tract, and lymph nodes

• Retroperitoneal nodes and masses

Size

• Variable: Ranges from microabscesses (< 1 cm) to large masses due to lymphoma or Kaposi sarcoma

Morphology

• Bulky hepatic or GI tract masses from AIDS-related lymphoma

Best imaging tool

• CECT

Protocol advice

• IV and oral contrast

Liver

• Liver may appear nodular and cirrhotic due to strong demographic overlap of HIV and chronic viral hepatitis

• Small hypodense nodules scattered throughout liver suggests microabscesses [often due to Mycobacterium avium-intracellulare (MAI), tuberculosis, histoplasmosis, Candida , Pneumocystis , etc.]

• Liver may appear globally enlarged without focal lesions due to infiltrative infections (e.g., MAI)

• Pneumocystis (and rarely CMV or MAI) can result in multiple tiny calcifications throughout liver

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    Calcifications do not signify inactive disease

• Liver is involved in up to 1/4 of patients with AIDS-related lymphoma, with hypodense nodules of variable size

Biliary tree

• Cholangitis may be caused by opportunistic infections

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    Intrahepatic and extrahepatic biliary strictures with papillary stenosis: Bile ducts may appear thickened and enhancing

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    Bile ducts may have beaded appearance very similar to primary sclerosing cholangitis

• Acalculous cholecystitis may due to opportunistic infections (e.g., CMV, Cryptosporidium )

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    Thickened gallbladder with pericholecystic fluid and stranding

Spleen

• Splenomegaly in up to 3/4 of AIDS patients even without infection or tumor

• Small tiny hypodense foci (microabscesses) usually due to disseminated infection (e.g., Candida , MAI, tuberculosis, Pneumocystis , etc.)

• Larger hypodense lesions might still be infectious, but AIDS-related lymphoma should also be considered

• Small calcifications (similar to liver) from Pneumocystis

Stomach, small bowel, and large bowel

• Bowel wall thickening, mucosal hyperemia, and fat stranding surrounding bowel should always raise concern for infection (including opportunistic infections)

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    CMV-related ulcerations of bowel may lead to GI tract perforation (one of most common reasons for emergent abdominal surgery in AIDS patients)

• Most opportunistic infections can involve any segment of GI tract ( Cryptosporidium , CMV, MAI, tuberculosis, microsporidium, Clostridium difficile , amebiasis, etc.)

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    Difficult to predict pathogen based on distribution, but some organisms have predisposition for certain locations

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      CMV and TB tend to involve ileum

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      Giardia , microsporidium tend to involve proximal small bowel

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      Colon infections often due to CMV, C. difficile , Campylobacter , amebiasis, Salmonella , and Shigella

• Mural thickening of esophagus suggests esophagitis, often due to candidiasis, CMV, or herpes simplex

• Proctitis in homosexual men due to sexual activity may be due to Neisseria gonorrhoeae , chlamydia, or HSV

• Focal mass-like wall thickening anywhere in GI tract should raise concern for malignancy (AIDS-related lymphoma, Kaposi sarcoma)

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    Lymphoma associated with intussusceptions

Lymph nodes

• Mild generalized lymphadenopathy (< 1.5 cm) is usually reactive and may be 1st clue to HIV infection

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    May persist for years in absence of symptoms (i.e., persistent generalized lymphadenopathy)

• More significant adenopathy (> 1.5 cm) suggests opportunistic infection (MAI, tuberculosis) or AIDS-related lymphoma/Kaposi sarcoma

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    Necrotic mesenteric nodes from MAI or tuberculosis

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    Hyperenhancing lymph nodes in Kaposi sarcoma

• AIDS-related lymphoma may be associated with discrete lesions in liver/spleen or focal mass in GI tract

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    GI tract most common extranodal site of involvement (75%), most often involving colon, ileum, and stomach

Kidneys

• Bilateral large kidneys with urothelial thickening due to HIV nephropathy

• Focal hypodense lesions could reflect infection (tuberculosis, MAI, fungus) or AIDS-related lymphoma

• Calcifications may be present in setting of Pneumocystis (similar to liver and spleen) or rarely MAI/CMV

Pancreas

• Opportunistic infections can cause acute pancreatitis and pancreatic duct strictures (e.g., CMV, Cryptococcus , etc.)

Lungs: Pneumocystis pneumonia (PCP), tuberculosis