Primary gastric actinomycosis: report of a case diagnosed in a gastroscopic biopsy

Abstract

BackgroundPrimary gastric actinomycosis is extremely rare, the appendix and ileocecal region being the most commonly involved sites in abdominopelvic actinomycosis. Herein, we report a case of primary gastric actinomycosis. The diagnosis was made on microscopic evaluation of gastroscopic biopsy specimens. To the best of our knowledge, this is the third case to be reported in the literature, in which the diagnosis was made in a gastroscopic biopsy rather than a resection specimen.Case presentationAn 87-year-old Saudi male on medication for cardiomyopathy, premature ventricular contractions, renal impairment, hypertension, and dyslipidemia, presented to the emergency department with acute diffuse abdominal pain, abdominal distension, constipation and vomiting for two days, with no history of fever, abdominal surgery or trauma. The patient was admitted to the hospital with an impression of gastric outlet obstruction. Based on radiologic and gastroscopic findings, a non-infectious etiology was suspected, possibly adenocarcinoma or lymphoma. Gastroscopic biopsies showed an actively inflamed, focally ulcerated atrophic fundic mucosa along with fragments of a fibrinopurulent exudate containing brownish, iron negative pigment and abundant filamentous bacteria, morphologically consistent with Actinomyces.ConclusionAlthuogh extremely rare, primary gastric actinomycosis should be considered in the differential diagnosis of radiologic and gastroscopic diffuse gastric wall thickening and submucosal tumor-like or infiltrative lesions, particularly in patients with history of abdominal surgery or trauma, or those receiving extensive medication. A high level of suspicion is required by the pathologist to achieve diagnosis in gastroscopic biopsies. Subtle changes such as the presence of a pigmented inflammatory exudate should alert the pathologist to perform appropriate special stains to reveal the causative organism.

Actinomycesand Alimentary Tract Diseases: A Review of Its Biological Functions and Pathology

“…Although the patient (87 years old) did not have a history of trauma or underwent abdominal surgery, the patient was prescribed medication over a long period for dyslipidemia, renal impairment, premature ventricular contractions, nonischemic cardiomyopathy, and hypertension. The author suggested that the drugs the patient took would have caused damage to the gastric mucosa and that age-related mucosal atrophy was able to induce diminished mucosal resistance [ 58 ]. Therefore, actinomycosis frequently occurs in immunodeficient or immunocompromised patients due to other infections or the prescribed medication.…”

“…Diagnosis. Any abscesses or persistent infections in the alimentary tract should be suggestive of actinomycosis, although the symptomatic diagnoses of these infectious diseases are often painless [ 65 ] and accompanied by other systemic diseases [ 58 , 61 , 62 ]. It is important for physicians to be aware that actinomycosis frequently ‘imitates' malignancy nocardiosis or tuberculosis [ 5 ] as it can spread to distant tissues and organs in the human body progressively to form abscesses, which is analogous to tumor metastasis through invasive mechanisms.…”

“…For suspected actinomycosis in the alimentary tract, endoscopic examinations and CT scans are useful to gain an overview of the lesions. A biopsy should also be used to facilitate a histological examination [ 58 , 59 , 62 ], but, in some cases, actinomycotic infections can be identified after the histological examinations of surgical specimens, as the lesions are resected after misdiagnosis [ 55 , 57 ]. In a rare case of ascending colon actinomycosis, Filippou et al applied CT imaging to identify a tumor-like mass.…”

“…For cases of esophageal actinomycosis, systemic intravenous penicillin treatment is usually needed, and the combination of penicillin G and amoxicillin has also been reported [ 60 ]. In one patient with gastric actinomycosis, the empiric antibiotic therapy of IV metronidazole and IV levofloxacin were prescribed resulting in a complete cure [ 58 ].…”

“…Some cases and studies in animals indicated that the damage of the wall of the digestive tract was one of the leading etiology causes of actinomycosis [ 93 ], but primary gastric actinomycosis was also reported [ 58 ]. Therefore, further studies on the pathogenesis of the actinomycosis in the alimentary tract are required.…”