title: Primary gastric actinomycosis: report of a case diagnosed in a gastroscopic biopsy.
abstract: BACKGROUND
  Primary 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.
  
  
  METHODS
  An 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.
  
  
  CONCLUSIONS
  Althuogh 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.
authors.affiliation: Pathology Department, College of Medicine, University of Dammam, P.O. Box 1982, Dammam, 31441 Saudi Arabia.
authors.forename: Khaleel
authors.initials: K
authors.lastname: Al-Obaidy
authors.affiliation: Pathology Department, College of Medicine, University of Dammam, P.O. Box 1982, Dammam, 31441 Saudi Arabia.
authors.forename: Fatimah
authors.initials: F
authors.lastname: Alruwaii
authors.affiliation: Pathology Department, College of Medicine, University of Dammam, P.O. Box 1982, Dammam, 31441 Saudi Arabia.
authors.forename: Areej
authors.initials: A
authors.lastname: Al Nemer
authors.affiliation: Department of Internal Medicine, College of Medicine, University of Dammam, P.O. Box 1982, Dammam, 31441 Saudi Arabia.
authors.forename: Raed
authors.initials: R
authors.lastname: Alsulaiman
authors.affiliation: King Fahd Hospital of the University, University of Dammam, P.O. Box 2208, Al-Khobar, 31952 Saudi Arabia.
authors.forename: Zainab
authors.initials: Z
authors.lastname: Alruwaii
authors.affiliation: Pathology Department, College of Medicine, University of Dammam, P.O. Box 1982, Dammam, 31441 Saudi Arabia.
authors.forename: Mohamed A
authors.initials: MA
authors.lastname: Shawarby
keywords: Actinomycosis; Gastric; Gram; Grocott’s; PAS