Weekly blog - Liver lesions (to aspirate or not to aspirate)

Aspirations of liver lesions... it’s not just about their hopes and dreams.

Today in rounds we discussed a case of liver lesion and debated as to whether or not it should have been drained.  In the case of a cystadenocarcinoma you may want to avoid drainage to prevent disease dissemination; in contrast, drainage of a pyogenic liver abscess is a common therapeutic and diagnostic procedure. 

Here’s a review on how to differentiate cystadenocarcinoma from liver abscess: https://webvpn.mcgill.ca/http/www.sciencedirect.com/science/article/pii/S0039610910000393

The bottom line is that a cystadenocarcinoma that secretes mucin can be difficult to distinguish from a pyogenic abscess based on imaging.  

It can be helpful to identify patient risk factors for pyogenic abscess. In a susceptible patient presenting with infectious symptoms, you will likely aspirate the lesion to avoid unnecessary surgical intervention and the associated morbidity and mortality.

Host factors and susceptibilities for pyogenic liver abscess:

·     *  delayed treatment of intraabdominal processes (appendicitis, diverticulitis, cholecystitis)

·     *  biliary obstruction, stenting, or manipulation

·     * diabetes/immunosuppression/congenital immune deficiency (i.e. Chronic Granulomatous Disease)

·     * endocarditis or IVDU (leading to hematogenous spread)

The original 1946 NEJM article describing the “five ways in which pyogenic organisms invade the liver”:

https://webvpn.mcgill.ca/http/www.nejm.org/doi/pdf/10.1056/NEJM194603212341203

See previous blog on this issue here and my color rendition of the mechanisms

Microbiology (not an exhaustive list):

·         Polymicrobial, gram negatives and anaerobes

·         S. milleri /S. anginosus, S. aureus, S.pyogenes (and other gram positive cocci),

·         Klebsiella pneumonia (think of this pathogen in patients with diabetes, particularly with monomicrobial abscess with metastatic spread to other organs)

·         Other: Candida, Tuberculous, Burkholderia. Amebiasis.

Some diagnostic pearls pertaining to liver abscess:

·         Initially, an abscess may be hyperechoic and indistinct; but with maturation and pus formation, it becomes hyperechoic with a distinct margin. Thick pus or multiple small lesions might be confused with solid lesions

·     

    Peripheral enhancement on CT is VERY helpful!

·         Don’t forget to do blood cultures (non invasive, though sensitivity only about 40%)

·   

I   Infectious symptoms may only occur late. “Large infections with bacteria of modest virulence can develop with only subtle symptoms.”  To illustrate this point, here is a case of pyogenic liver abscess, caused by strep mitis:

https://webvpn.mcgill.ca/http/www.sciencedirect.com/science/article/pii/S147330991370166X

Any discussion of indolent abscess should also include a nod to S. milleri group organisms.

To learn about klebsiella pneumonia liver abscess (a 2013 review of the European literature with some illustrative case reports from the journal Infection):

https://webvpn.mcgill.ca/http/download.springer.com/static/pdf/639/art%253A10.1007%252Fs15010-013-0408-0.pdf?auth66=1405612498_f6a242bfba61dae025ccc76b7078bb4b&ext=.pdf

See the previous blog on this particular entity here. 

Finally, a “NEJM case records of the Massachusetts General Hospital”, looks at a case of liver abscess (read more to find out what interesting pathogen was involved in this case!)

https://webvpn.mcgill.ca/http/www.nejm.org/doi/full/10.1056/NEJMcpc069017

- egm and tcl