Step 3: Generate a Differential Diagnosis

Objective :

Use a Diagnostic Sieve to generate a differential diagnosis list

Diagnostic sieves are a valuable and efficient way of assessing a patient's symptoms and signs to reach a diagnosis.

Click on the categories that are relevant to this case. Correct answers are highlighted in green.


This could be a popliteal artery aneurysm, however the fact that the mass is firm and fixed counts against it. Also, it was not pulsatile.

Inflammatory / Infection

This could be an abscess or parasitic cyst.


The history of a rapidly growing mass, combined with the exam findings of a hard and fixed mass make a neoplasm a definite possibility.


A hematoma could present like this, if there was a history of trauma or he was on anti-coagulants.

Next Step

Open ended questions establish which symptoms are most important to the patient and promote good rapport.