Introduction:
Colorectal cancer is one of the most common type of cancers worldwide. Simultaneous occurrence of at least two tumours in a single patient within 6 months is defined as synchronous colorectal carcinoma (SCC). Within all large intestine tumors, the occurrence of SCC is approximately 3.5%. Patients with more than two tumours account for 1.8% to 16.7% of all SCC cases.

Aim:
We present a case of a 65-year-old female patient with triple synchronous colorectal cancer.

Case study:
65-year-old female patient reporting increasing fatigue and shortness of breath, lasting for 6 months, underwent preoperative colonoscopy and computed tomography (CT) scan. Both examinations indicated double malignant lesions in separate parts of the transverse colon. During the subtotal colectomy a third lesion has been found.

Results and discussion:
The histopathology results confirmed three adenocarcinoma type tumours (two of grade 3 and one grade 2). Our patient does not suffer from any conditions that increase the probability of SCC. In her family history there are no known ancestors suffering from colon cancers or multiple primary malignant tumor. The patient does not suffer from ulcerative colitis or familial adenomatous polyposis.

Conclusions:
The presented clinical case proves that a comprehensive pre-surgical recognition of SCC is not always possible. If a full colonoscopy is impossible, one should consider carrying out a second colonoscopy 3 months after a surgery, particularly in case of patients whose CT results are ambiguous. During a surgery, the entire length of the bowel should be palpably checked for a presence of additional tumours.