What condition is indicated by an infiltrate in the shape of a butterfly?

The presence of a butterfly-shaped infiltrate on chest imaging is most commonly associated with pulmonary edema. This characteristic appearance arises because pulmonary edema typically leads to fluid accumulation in the perihilar regions of the lungs, creating a pattern that resembles a butterfly or bat spread across the central lung fields.

In pulmonary edema, the excess fluid in the alveoli affects gas exchange and can make presentation in imaging quite distinct, often resulting in bilateral infiltrates that are symmetric and can appear in a “bat-wing” distribution. This is particularly relevant in conditions such as congestive heart failure, where fluid overload occurs leading to the typical findings on imaging.

The other conditions mentioned can cause infiltrates but do not typically present with the butterfly pattern. For instance, pneumonia presents with localized infiltrates that are often lobar or segmental rather than the distinct bilateral pattern seen with pulmonary edema. Pleural effusion typically shows as a meniscus or blunting of the costophrenic angles on imaging, while ARDS (Acute Respiratory Distress Syndrome) or IRDS (Infant Respiratory Distress Syndrome) may show diffuse infiltrates but lack the characteristic shape associated with pulmonary edema. Thus, the butterfly-shaped infiltrate is a key indicator pointing to pulmonary edema