In the studied patient group, we encountered a very rare case of multiple location small bowel sarcomatous carcinoma, and the immunohistochemistry was definitive in formulating the diagnosis (Figure 9, Figure 10, Figure 11 and Figure 12) by excluding a malign melanoma, an epithelioid gastrointestinal tumor, neuroendocrine tumor, or a metastasis; thus, the deficit of SMARCB1/INI1 of an undifferentiated carcinoma supported the sarcomatous carcinoma diagnosis. The gene discussed is SMARCB1; the disease is cancer.