Gastrointestinal stromal tumors arising in the perianal and perineal region: Two case reports and literature review

INTRODUCTION AND IMPORTANCE: Gastrointestinal stromal tumor (GIST) is rare because of its variable clinical incidence reported (from 0.4 to 2/100,000 per year) in the literature, mainly occurs primarily in the stomach and small intestine. GISTs in the perianal and perineal regions have been reported in a few pieces of literature. GIST located in the perianal and perineal regions may be misdiagnosed and missed due to atypical symptoms. We report two cases of GIST in rare sites and hope to reduce the occurrence of such events through a review of the relevant literature. CASE DESCRIPTION: We reported two cases of GIST located in the perianal and perineal regions with different symptoms. One case underwent an emergency procedure to stop bleeding and resect the mass, and the other case was discovered during the physical examination and slowly grew in the follow-up. Following the completion of the relevant examination, the patient underwent surgical resection. Both cases were finally diagnosed as GIST by immunohistochemistry. CLINICAL DISCUSSION AND CONCLUSION: Due to atypical clinical symptoms of perianal and perineal GIST, definitive diagnosis depends on pathology and immunohistochemistry, which can lead to misdiagnosis and missed diagnosis. Surgical resection is the preferred option for localized masses. Surgical resection of GIST located in the perianal and perineal regions requires an appropriate surgical approach based on the patients' actual condition, taking into account the protection of anal function and complete resection of the mass. Masses located in perianal and perineal region should be taken seriously by clinicians.