Primary leiomyosarcoma of the colon with synchronous liver metastasis

Leiomyosarcomas (LMS) are mesenchymal tumors of smooth muscle origin. Approximately 20% of leiomyosarcomas are found in the GI tract, and account for 1–2% of GI malignancies. Within the gastrointestinal tract, the small intestine is the most common site of presentation followed by the colon. They are often diagnosed incidentally during abdominal pain investigation, and they usually present in the fifth decade of life. In the past, the diagnostic differentiation between leiomyosarcomas of gastrointestinal tract and gastrointestinal stromal tumors (GISTs) was very challenging as they share common microscopic appearance. Nowadays, these tumors are diagnosed by immunohistochemical methods as they are positive for smooth muscle markers actin (SMA) and desmin, negative for GIST markers such as receptor tyrosine kinase (KIT), CD34, DOG1, and negative for the schwannoma marker S100 protein. In the current literature, most cases of intestinal leiomyosarcomas are localized in the small intestine, and there are no reports of synchronous liver metastases at the time of presentation of the primary tumor. Herein, we present a patient who was admitted in our department, with the diagnosis of primary leiomyosarcoma of the colon and synchronous liver metastasis.