Diagnosis: Endogenous lipoid pneumonia
Radiologic Findings |
History Frontal chest radiograph shows prominent left hilum, and a large increased density in left lower lung zone with volume
decrease without obliteration of left cardiac border. Left lateral chest radiograph shows consolidation of left lower lobe
with mild volume decrease. Contrast-enhanced chest CT scans show 1cm sized low-density mass in left lower lobar
bronchus and consolidations of left lower lobe with mucus-bronchogram. These findings suggest endogenous lipoid
pneumonia of left lower lobe due to endobronchial mass. |
Brief Review |
Endogenous lipoid pneumonia (ELP), which is also called as postobstructive pneumonitis occurs distal to major airway obstruction. ELP results from a variety of causes including neoplasm and infection. Pathologically it is a combination of atelectasis, bronchiectasis with mucous plugging, and parenchymal inflammation and fibrosis. The lobes often have yellowish or golden hue, which is thought to be produced by the liberation of lipid material from alveolar pneumocytes secondary to the inflammatory reaction. This appearance has given rise to the term golden pneumonia; this abnormality is also known as cholesterol pneumonia. In the vast majority of the cases the inflammation is not caused by bacterial infection. In involved parenchyma that has been recently obstructed, the principal histologic finding is filling of alveolar air space by proteinaceous fluid containing scattered macrophages and cultures are usually sterile. In later stages fluid is replaced by macrophages containing foamy and vacuolated cytoplasm, which is different from the large vacuoles in exogenous lipoid pneumonia. Etiologies of ELP include malignant neoplasms, such as bronchogenic squamous or small cell carcinoma, carcinoid, mucoepidermoid carcinoma; metastatic carcinoma from kidney, colorectum, breast or melanoma; benign rare bronchial tumors such as endobronchial hamartoma, lipoma or schwanoma; other occluding lesions such as mucus plug, foreign body or bronchial fracture; infection such as endobronchial tuberculosis, endobronchial actinomycosis; inflammatory lesions such as antracofibrosis or broncholithiasis; or middle lobe syndrome. This case was due to small cell lung cancer. Small cell carcinoma is typically located in relation to proximal airways, particularly lobar and main bronchi. Centrally located tumors tend to spread in the submucosa and peribronchovascular connective tissue, and then extend into adjacent lung parenchyma to become a more circumscribed mass that obliterates underlying airways and vessels. Endobronchial growth is seen much less frequently than in squamous cell carcinoma; in fact when airway obstruction occurs, it is usually as a result of compression by the expanding tumor rather than intraluminal growth. CT can better depict the extent of the mass as well as the nature of it.
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References |
1. Burke M, Fraser R. Obstructive pneumonitis: a pathologic and pathogenetic reappraisal. Radiology
1988;166:699-704 3. Genereux GP. Lipids in the lungs: radiologic-pathologic correlation, J Canad Assoc Radiol 1970;21:2-15 4. Carter D. Small cell carcinoma of the lung. Am J Surg Pathol 1983;7:775-785 |
A Letter from Dr. Kyung Soo Lee, Editor of the Website.
Dear Dr. Kim:
Endobronchial mass in left basal trunk with atelectasis of left lower lobe in a 70-year-old man.
Corresponding bronchial wall is somewhat thickened, however, there is no definite evidence of extraluminal invasion.
We do not know attenuation value or the degree of enhancement of endobronchial mass.
DDx should include mucoepidermoid carcinoma, carcinoid (less likely in consideration of gender and age), leiomyoma,
and hamartoma or lipoma (less likely due to absence of fat attenuation).
With best wishes.
Kyung Soo Lee, MD