TB or Not TB: An Unusual Case of Gastric Adenocarcinoma Obscured by the Diagnosis of Tuberculosis in a 34 Year Old Patient

Abstract

Purpose: The gastrointestinal tract can be involved in a multiplicity of medical conditions creating a formidable diagnostic challenge. It is one of the most common locations for extra-pulmonary tuberculosis and also where multiple malignancies occur. Gastric adenocarcinoma usually occurs in patients between their fifth and seventh decade of life. Approximately two to five percent of cases are diagnosed in patients less than 40 years of age. We present a complex case where the diagnosis of gastric adenocarcinoma in a young patient was delayed due to the concurrent diagnosis of latent tuberculosis. Our patient is a 34 year old male who presented to our department for workup of unexplained ascites and abdominal lymphadenopathy from an outside facility. Extensive workup including multiple paracentesis, imaging studies, diagnostic pan endoscopy and liver biopsy did not reveal the cause of his exudative ascites. The patient reported a diagnosis of tuberculosis in recent years but did not undergo treatment at that time. Both purified protein derivative and interferon-gamma release assay (Quantiferon®-TB Gold In-Tube®) tests were positive. Diagnostic laparoscopy showed small nodules throughout the peritoneum and the small intestines suggestive of miliary pattern. Peritoneal biopsy was performed which revealed chronic inflammation but no acid fast bacilli. The patient was started on four-drug therapy for tuberculosis for 12 weeks with no response. Worsening of his ascites and absence of improvement despite aggressive treatment prompted re evaluation of his diagnosis. Repeat cytological examination of his ascetic fluid with re evaluation of his peritoneal biopsies raised the suspicion of metastatic signet cell carcinoma. Repeat endoscopic examination with extensive biopsies of the stomach, small bowel and colon mucosa showed gastric adenocarcinoma with features suggestive of linitis plastica.