Friday, May 11, 2012

Bilateral Lower Lung Disease: Differential Diagnosis #11

The Daily Diff for today is bilateral lower lung disease. Like the previous post on bilateral upper lung disease, several entities commonly cause disease in this pattern. A rough rule of thumb with diseases in the lung is that air rises (ie, endobronchial spread will disproportionately affect the upper lung zones - think TB) and that blood falls (ie, hematogenous spread goes toward the lower lobes). As you'll see below, the rule is quite rough, but is worth keeping in mind. Anyway, keep in mind the phrase BAD LASS when you see bilateral lower lung disease. Not sure what naughty schoolgirls have to do with the lower lung zones, but if it helps you remember...

Desquamative interstital pneumonia
Ex. amiodarone, bleomycin, cyclophosphamide, carmustine
LLymphangitic spread of carcinoma

Clearly, the clinical context will make a big difference in narrowing down the differential to a top diagnosis.

Bleomycin Toxicity
Source: Postgraduate Medical Journal