Day #231 - Cavitary Lung Lesions

Today we discussed an immunosuppressed patient with bilateral upper lobe cavitary lung lesions. The differential diagnosis for such lesions in the immunocompetent includes:








Infection:

• TB or Atypical Mycobacterial Disease
• Cavitary Pneumonia
  
  • Gram negatives (Klebsiella, E. Coli, Pseudomonas)
  • Gram positives (Staphylococcus aureus (particularly CA-MRSA), group A streptococci)
  • Anaerobes (Lung Abscess)
• Fungal: Aspergillosis, Histoplasmosis, Coccidiomycosis, Blastomycosis, Cryptococcus
• PCP
  
• Superinfection/Colonization of an existing cavity
  
  • Aspergilloma ("fungus ball" or mycetoma)
• Septic pulmonary emboli with cavitation

Inflammatory:

• Wegner's Granulomatosis
• Rheumatoid Arthritis
• Sarcoidosis (rare)
  

Vascular

• Pulmonary Infarct

Malignancy:

• Bronchoalveolar carcinoma
• Bronchogenic carcinoma
  
• Squamous cell cancer of lung
  
• Cavitating metastases

Anotomical:

• Cystic Bronchiectasis

Day #230 - Eosinophillia and Pulmonary Infiltrates

Today we heard a case of a patient with 2 weeks of fever and cough with diffuse abnormal chest x-ray infiltrates and profound eosinophilia.

This differential diagnosis of pulmonary eosinophilia is discussed here. Another good review is available here.

Interestingly -- there are case reports of SSRI induced eosinophilic pneumonia and our patient in this case was on two different SSRIs.

Day #229 - Strep Throat plus or minus HSV Encephalitis

We heard a case today for which the diagnosis was unclear. The patient presented with a febrile illness with odynophagia and headache accompanied by hallucination which was ascribed to group A streptococcus.

A review of the neurologic sequelae of GAS infection is available here. There has been a link between GAS infections and neuropsychiatric symptoms (primarily OCD and tic disorders) in children.

He was also treated for HSV encephalitis because of fever, headache, and the development of seizures. This was despite an initially negative HSV PCR. Many experts will continue treatment and repeat the LP in 3-7 days in patients in whom they have a high index of suspicion. This would be such a case. The ID Society of America has guidelines on the management of viral encephalitis available here. This article outlines the risk factors for severe disease and poor outcome in HSV encephalitis.

Day #208 - Cryptococcal Meningitis

We resurrected an old case today. I've previously blogged about cyrptococcal meningitis here and here. There are useful links to the HIV guidelines on those pages.

Here is a link to a talk I once gave on "the basics" of HIV.