Liver Lesions, Abcesses & Hydatid Cysts

1) Review differential diagnosis/classification of liver lesions

Malignant - Metastases (majority), Primary - Hepatocellular CA, CholangioCA, Angiosarcoma
Non-Malignant

          1) Benign Growths - Hepatic Adenomas, Focal nodular hyperplasia, Cavernous Hemangiomas
          2) Cysts - Simple cysts, Cystadenomas, Biliary cysts (choledochal cysts), Hydatid cysts (echinococcus)
          3) Abscesses (see below)

2) Review microbiology and therapy of liver abscesses

- Main distinction is Pyogenic abscess vs Amebic Abscess

Pyogenic abscess - arise mainly from 1) Direct extension from biliary infection (cholangitis) into liver, 2) Spread from portal circulation of intraabdominal infection (peritonitis, diverticulitis, etc), 3) Hematogenous seeding

          - Microbiology: Polymicrobial - mostly enteric gram negatives and anaerobes, Staph and Strep (including Strep anginosus group - propensity for abscesses), Klebsiella
            pneumoniae (including hypermucoid strain), Candida (hepatosplenic candidiasis in recovered neutropenic fever patient)
          - Therapy - need drainage!! IR vs surgical (depending on size) + prolonged course of Abxs (typically 4-6 weeks)

Amebic abscess - Entamoeba histolytic - important to distinguish from pyogenic , as often do NOT need drainage and can treat with short course of Metronidazole, followed by luminal agent such as Paroromycin

3) Brief overview of Echinococcosis and Hydatid Cysts

- Tapeworm, definitive host = canines, intermediate hosts = sheep, also humans
- Eggs shed in feces from canines, transmitted by fecal-oral route to sheep (or humans), ingested --> hatch in intestine and crawl through wall, spread via blood/lymphatics into liver --> form cysts. In definitive hosts, life cycle continues until full worms mature and spread to intestine again. In intermediate hosts, stays as cysts in the liver, spread via ingestion of organs.
- Main organs affected are liver >> lungs
- Symptoms arise from cysts 1) Mass effect on nearby structures, 2) Rupture - peritonitis, anaphylaxis, 3) Bacterial Superinfection
- Treatment = Surgical vs IR (PAIR procedure = puncture, aspirate, inject, reaspirate) + Albendazole/Mebendazole as an adjunct

(Chanu Rhee MD, 7/8/10)