That’s Rancid

This is a case of a 45 y/o incarcerated, actively smoking gentleman with severe GERD, seizure disorder due to EtOH withdrawal who presented with cough productive of gray, foul smelling (not only to patient but innocent bystanders as well) sputum for 2 weeks. CXR on admission revealed a right upper lobe cavitary lesion which was confirmed on CT chest.  Rapid HIV negative, PPD negative,  AFB smear negative x3, Nucleic acid amplification test negative x1. Bronchoscopy and final diagnosis pending.

Differential Diagnosis of Solitary Cavitary Lung Lesion includes:  CAVITY

Cancer (Squamous cell CA vs. Lymphoma vs. Metastatic CA)

Autoimmunue (Wegener’s vs. Rheumatoid Nodule vs. Sarcoidosis

Vascular (Pulmonary Embolism with infarction)

Infection (Mycobacterial vs. Bacterial vs. Fungal vs. Parasitic vs. Septic Emboli)

Trauma (Bullous Lung Disease)

Youth (Congential pulmonary cysts)

LEARNING POINTS

-Radiographic characteristics on CT chest can be helpful in guiding diagnosis:

1) Wall thickness (<5mm almost always signifies benign process, >15mm almost always malignant)

 2) Wall contour (irregular/nodular appearance predominantly points towards malignant process vs. smooth appearance is associated with infection)

3) Surrounding Lung Parenchyma: if cavitary lesion is surrounded by infiltrate/consolidation, then infection is highly likely

4) Solitary vs. Diffuse Cavitary Lesions

-When ordering sputum AFB for smear and culture, our lab now reflexively also sends nucleic acid amplification testing (NAAT) which helps identify tuberculous mycobacteria, if present. Thus, in setting of positive AFB smear (which only identifies mycobacteria), NAAT can help distinguish between nontuberculous and tuberculous species of mycobacteria.

References:

 http://www.ncbi.nlm.nih.gov/pubmed/12934786

http://www.ncbi.nlm.nih.gov/pubmed/18400799