A rare case of synchronous leiomyosarcoma in the jejunum and sigmoid colon

Leiomyosarcomas (LMSs) of the gastrointestinal tract are rare malignant tumors arising from smooth muscle cells. It is known for its aggressive nature and poor prognosis. Among gastrointestinal sites LMS, colonic involvement is exceptionally uncommon and often misdiagnosed as other more common colorectal malignancies such as adenocarcinoma or gastrointestinal stromal tumors (GIST). We report a case of a 37-year-old woman who presented with fever, vomiting, occasional abdominal pain, and constipation. Imaging revealed a left-sided abdominal mass likely of malignant nature. Histopathological examination following surgical resection confirmed the diagnosis of LMS, with immunohistochemistry showing positivity for smooth muscle actin, desmin, and negativity for CD117, DOG1, and CD34, excluding GIST. She thereafter received adjuvant chemotherapy with six cycles of doxorubicin and dacarbazine. There has been no recurrence until 9 months of follow-up postchemotherapy. Primary LMS of the colon is an extremely rare entity with nonspecific clinical features. A high index of suspicion, supported by immunohistochemical analysis, is crucial for accurate diagnosis. Early surgical intervention remains the mainstay of treatment, although prognosis remains guarded due to tumor's aggressive nature.