Just another negative DVT?

A 69-year-old woman presented to the emergency department (ED) with a swollen left thigh and leg. D-dimer test was positive, a radiology department ultrasound showed no direct evidence of a deep venous thrombosis but a lack of respiratory modulation was seen. ED ultrasound showed large groin lymph nodes and this, together with low haemoglobin, prompted a CT scan which led to the diagnosis of metastatic carcinoma.