ABSTRACT
Mycobacterium fortuitum is associated with skin and soft-tissue infections, yet isolated liver involvement is rare. A 67-year-old asymptomatic man was referred for endoscopic ultrasound (EUS) to evaluate a gastric lesion and an incidental liver mass. EUS revealed a heterogeneous liver mass that was sampled. Pathology revealed necrotic granulomatous inflammation and positive acid-fast bacilli stain with M. fortuitum deoxyribonucleic acid. Levofloxacin plus trimethoprim and sulfamethoxazole for 3 months were used for complete resolution of liver lesion. Isolated nontuberculous liver involvement is uncommon. We report the first case of a liver mass caused by M. fortuitum diagnosed by EUS-fine needle aspiration.
KEYWORDS: atypical mycobacteria, Mycobacterium fortuitum, liver mass, endoscopic ultrasound (EUS), fine needle aspiration (FNA)
INTRODUCTION
Mycobacterium fortuitum is a type of nontuberculous mycobacteria belonging to a group classified as rapidly growing mycobacteria and Mycobacterium abscessus and Mycobacterium chelonae. These nontuberculous mycobacteria can be found in soil and aquatic environments. Mycobacterium fortuitum is an opportunistic pathogen characterized by biofilm formation as attributed to known antibiotic resistance.1 M. fortuitum is predominantly associated with skin, soft-tissue, and surgical wound infections. Nosocomial infections such as catheter-related sepsis, prosthetic arthroplasty, and pacemaker infection have been fairly described. Disseminated diseases such as pneumonia, endocarditis, and meningitis can also occur.2 Isolated liver involvement by atypical mycobacterial infection is exceedingly rare. Here, we describe a case of M. fortuitum presenting as an asymptomatic liver mass.
CASE REPORT
A 67-year-old man was referred for endoscopic ultrasound (EUS) to evaluate a gastric body subepithelial lesion (SEL) and a 3 cm incidental liver mass described as a heterogenous enhancing liver lesion in the left liver lobe segment #2 and #3 (Figures 1 and 2). He was asymptomatic. Percutaneous computed tomography (CT)-guided liver biopsy was performed, but pathologic results were nondiagnostic. The patient was thus referred for EUS to evaluate the gastric SEL and determine whether the liver mass represented metastasis. A 14 by 4 mm elongated intramural hypoechoic mass arising from the muscularis propria was identified. A heterogeneous mass with cystic spaces and echogenic foci in the left liver lobe measuring 27 by 20 mm was sampled using a 22 g FNA needle (Figures 3 and 4). Pathology revealed granulomatous inflammation with necrosis. An acid fast bacilli stain was positive for acid-fast bacilli. Polymerase chain reaction analysis of the specimen detected M. fortuitum deoxyribonucleic acid. The patient was treated with levofloxacin 750 mg daily plus trimethoprim and sulfamethoxazole (Septra Double Strength) 800–160 mg twice daily. Follow-up contrast-enhanced MRI revealed complete resolution of the liver lesion after 3 months of antibiotics (Figures 5 and 6).
Figure 1.
T1-weighted imaging of the liver mass.
Figure 2.
T2-weighted imaging of the liver mass.
Figure 3.
Endoscopic ultrasound of the liver mass.
Figure 4.
Endoscopic ultrasound-fine needle aspiration of the liver mass.
Figure 5.
T1-weighted imaging of the liver posttreatment of M. fortuitum.
Figure 6.
T2-weighted imaging of the liver posttreatment of M. fortuitum.
DISCUSSION
The liver mass was initially believed to be evidence of a metastatic primary gastric tumor despite an isolated hepatic lesion found in the setting of a subepithelial lesion that is commonly found in routine examinations and usually benign in nature.3 Initial percutaneous CT-guided liver biopsy was nondiagnostic and falsely negative in retrospect, either from sampling error or from insufficient tissue acquisition. Acid-fast staining is not included in routine histopathology workup unless infectious etiology is considered in the differential diagnosis. A study revealed a diagnostic accuracy of 86% CT-guided liver biopsy of small focal liver lesions: 3 cm.4 Percutaneous liver biopsy suffers shortcomings in diagnostic accuracy because of the requirements of a large sample, operator's skill, and sampling error.5 EUS findings showed a gastric mass extending to muscularis propria highly suggestive of a gastrointestinal stromal tumor or leiomyoma,3 the latter is at low risk for malignant transformation.6 Gastrointestinal stromal tumor has the potential to metastasize, but, in our case, the lesion was in the stomach, was small in size (less than 2 cm) with an asymptomatic presentation; therefore, this SEL was a low risk for malignancy and therefore managed with annual endoscopic surveillance.7 Mycobacterium fortuitum has not been previously associated with liver involvement. By contrast, hepatic tuberculosis can emerge in a variety of presentations that include miliary tuberculosis, tuberculoma, pseudotumor, and abscess.
Abdominal MRI showed hyperintensity on T2-weighted imaging sharing similarities with radiologic findings of a hepatic tuberculoma or abscess.8 EUS showed no well-defined fluid collections but rather a hyperechoic mass in favor of a hepatic tuberculoma. Like a hepatic tuberculoma, this hepatic mass resolved with antimicrobial agents and did not require drainage. Few publications describe isolated liver involvement by an atypical mycobacterial infection,9,10 but none are associated with M. fortuitum.
Isolated liver involvement by nontuberculous mycobacteria is uncommon, usually asymptomatic, and its diagnosis can easily be missed or mistaken. We report the first case of a liver mass caused by M. fortuitum diagnosed by EUS-fine needle aspiration (FNA). Precise and accurate recognition by a minimally invasive technique such as EUS-FNA resulted in prompt treatment and resolution of the disease.
Disclosures
Author contributions: Y-S. Jao: conceptualization, investigation, writing, review & editing, and project administration. L. Martinez and VJ Carlo: conceptualization, investigation, and validation. C. Micames: conceptualization, investigation, writing, review & editing, and supervision.
Declaration of competing interest or financial support. Dr. Lemuel Martinez discloses being a speaker for Cubist Pharmaceuticals. Dr. Carlos G Micames has served as a consultant for Boston Scientific. The remaining authors have no financial interests disclosed related to this article.
Notice of prior presentation of the case report at a professional meeting: The case report was presented on October 24, 2022, at the ACG national conference meeting in Charlotte, NC.
Informed consent was obtained for this case report.
Contributor Information
Lemuel Martinez, Email: lemuelpr@yahoo.com.
Victor J. Carlo, Email: vjcarlo@prpathology.com.
Carlos G. Micames, Email: cmicames@gmail.com.
REFERENCES
- 1.Hall-Stoodley L, Lappin-Scott H. Biofilm formation by the rapidly growing mycobacterial species Mycobacterium fortuitum. FEMS Microbiol Lett 1998;168(1):77–84. [DOI] [PubMed] [Google Scholar]
- 2.Gutierrez C, Somoskovi A. Human Pathogenic Mycobacteria, Reference Module in Biomedical Sciences. Elsevier: Amsterdam, the Netherlands, 2014. [Google Scholar]
- 3.Menon L, Buscaglia JM. Endoscopic approach to subepithelial lesions. Therap Adv Gastroenterol. 2014;7(3):123–30. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4.Stattaus J, Kuehl H, Ladd S, et al. CT-guided biopsy of small liver lesions: Visibility, artifacts, and corresponding diagnostic accuracy. Cardiovasc Intervent Radiol. 2007;30(5):928–35. [DOI] [PubMed] [Google Scholar]
- 5.Sanai FM, Keeffe EB. Liver biopsy for histological assessment: The case against. Saudi J Gastroenterol. 2010;16(2):124–32. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 6.Humphris JL, Jones DB. Subepithelial mass lesions in the upper gastrointestinal tract. J Gastroenterol Hepatol. 2008;23(4):556–66. [DOI] [PubMed] [Google Scholar]
- 7.Polkowski M. Endoscopic ultrasound and endoscopic ultrasound-guided fine-needle biopsy for the diagnosis of malignant submucosal tumors. Endoscopy. 2005;37(7):635–45. [DOI] [PubMed] [Google Scholar]
- 8.Karaosmanoglu AD, Onur MR, Sahani DV, Tabari A, Karcaaltincaba M. Hepatobiliary tuberculosis: Imaging findings. Am J Roentgenol. 2016;207(4):694–704. [DOI] [PubMed] [Google Scholar]
- 9.Enweluzo C, Sharma A, Lenfest S, Aziz F. Non-tuberculous Mycobacterium: A rare cause of granulomatous hepatitis. Gastroenterol Res. 2013;6(2):71–3. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 10.Kanhere HA, Trochsler MI, Pierides J, Maddern GJ. Atypical mycobacterial infection mimicking metastatic cholangiocarcinoma. J Surg Case Rep. 2013;2013(6):rjt038. [DOI] [PMC free article] [PubMed] [Google Scholar]