Infections in the Gastrointestinal Tract That Can Mimic Malignancy

Infections in the gastrointestinal tract can present with the clinical impression of malignancy. These infectious mimics can take on a variety of forms from endoscopically concerning ulcers to large infiltrative masses and may be associated with lymphadenopathy and distant disease that is concerning for metastasis. In such cases, histopathology plays a key role in rendering a diagnosis of infection. In this review, we summarize the common and rare gastrointestinal infectious mimics of malignancy reported in the English medical literature. Microorganisms of all types have been implicated including bacteria, viruses, fungi, and parasites. Common bacterial causes include tuberculosis, actinomycosis, syphilis, and lymphogranuloma venereum. A small number of cases are due to other bacteria such as Helicobacter, Yersinia, α-hemolytic Streptococcus and Rhodococcus. The most common viral mimic of malignancy is cytomegalovirus; however, herpes simplex virus and Epstein-Barr virus have also been reported. Frequent fungal causes include histoplasmosis, mucormycosis and basidiobolomycosis; with a small number of cases due to candidiasis, aspergillosis and paracoccidiomycosis. Parasitic mimics of malignancy are less common. They include mostly protozoal infection such as amebiasis; however, a handful of various helminth infections (anisakiasis, strongyloidiasis, enterobiasis, trichuriasis, schistosomiasis, fascioliasis, echinococcosis) have also been reported. In summary, infectious etiology should be considered in the differential diagnosis of lesions in the gastrointestinal tract that are suspicious for malignancy.