Deep venous thrombosis as the single sign of unexpected metastatic urinary tract cancer in a patient with a history of cutaneous melanoma: A case report

INTRODUCTION: Cancer is a recognized risk factor of venous thromboembolism (VTE) as it induces a prothrombotic state through various mechanisms of activation of coagulation. Recognizing occult cancer as a risk factor is equally important. In patients with no known thromboembolic risk factors, utilizing PET/CT as a screening tool may be considered in order to reveal occult malignancy associated with otherwise unexplainable VTE. METHODS: This case report has been reported in line with the SCARE criteria. PRESENTATION OF CASE: We describe a case of deep venous thrombosis of the lower leg as the single sign of metastatic urinary tract cancer. The patient had a history of cutaneous melanoma but no thromboembolic risk factors. Following treatment for deep venous thrombosis, the patient was referred directly to the plastic surgery department for further examination including PET/CT due to suspicion of metastatic melanoma. DISCUSSION: Screening for occult cancer in patients with unprovoked VTE has so far not been shown to benefit survival. As new treatments emerge, significant improvement in prognosis might be expected with early diagnosis of occult cancer and initiation of treatment. Thus an open mind should be kept towards utilizing advanced diagnostic tools such as PET/CT to screen for occult cancer in patients presenting with unprovoked VTE. CONCLUSION: This case highlights the importance of considering all possible causes and utilizing targeted diagnostic tools when assessing a patient with seemingly unprovoked deep venous thrombosis. A whole-body PET/CT scan ultimately proved significant in revealing occult metastatic cancer of a completely different origin than expected.