Definitions of Densities
A mass is a large, rounded opacity generally greater than 3 cm in diameter.
Conglomerate masses have irregular shapes due to confluence of nodules or masses.
Nodules are less than 3 cm in diameter.
Case 8
Section 1
The next two images show densities of varying shapes and sizes in adjacent HRCT slices.
Image 1
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Definitions of Densities A mass is a large, rounded opacity generally greater than 3 cm in diameter. Conglomerate masses have irregular shapes due to confluence of nodules or masses. Nodules are less than 3 cm in diameter. | ||||||||||||||||||
Image 2
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Cavities within a mass, nodule, or region of consolidation are air-filled spaces that do not correspond to preformed structures. | ||||||
Section 2
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Find and outline a group of coarse centrilobular nodules in the right lung. Find a single coarse centrilobular nodule in the left lung. Find a conglomerate mass that causes deviation of the major fissure in the right lung. This deviation signifies fibrotic architectural distortion. | ||||||||||||||||||
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Find a group of fine centrilobular nodules (rosette) in the left lung. Find a fine tree-in-bud pattern in the left lung and a coarse one in the right lung. Find a conglomerate mass in the right lung. Find a conglomerate mass containing a cavity (not marked). | ||||||
Section 3: Gross Appearance
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Slice of Lung with a Necrotizing, Cavitating Mass This slice of lung has a mass of conglomerate nodules in the posterior segment of the upper lobe. The opaque white regions in the mass represent necrosis, and the pinkish areas, viable inflammatory infiltrates. The irregularly-shaped slits represent cavitation. Find two slits. Note the satellite centrilobular nodules, indicating in this case an endobronchial spread of disease. Find 2 centrilobular nodules in a lobule outlined by edematous, grey, interlobular septa. Note also the centrilobular nodules in another lobule just below this one. | ||||||
Section 4
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Histology of a Representative Lesion Outline and describe (name) the type of tissue at the lower right. How would you describe the inflammatory response in the rest of the picture? Find and name 4 of the large, multinucleated cells in the inflammatory infiltrate. What types of cells compose the rest of the infiltrate? | ||||||
Differential diagnosis of centrilobular nodules and cavitating masses on HRCT: The findings are characteristic of tuberculosis but other infections--fungal, nontuberculous mycobacterial, and chronic bacterial--can have a similar appearance. Centrilobular nodules and cavitating masses can also be seen with Langerhans' cell histiocytosis, sarcoidosis, silicosis, coal workers' pneumoconiosis, Wegener's granulomatosis, and rheumatoid arthritis.
Histologic differential diagnosis: Diagnoses to be considered include infectious granulomas (mycobacterial and fungal) as well as Wegener's granulomatosis, rheumatoid nodules, and nodular, necrotizing sarcoidosis.
Diagnosis: Tuberculosis
Summary of diagnostic features of endobronchial tuberculosis on HRCT
See Case Study 32 for other examples of tuberculosis (several are linked to the Discussion).
Coarse centrilobular nodule(s)
Fine centrilobular nodules (rosette)
Slit representing early cavitation
Langhans' giant cell (with peripheral nuclei)
Foreign body giant cell (with central nuclei)
The cells other than the multinucleated giant cells are mainly lymphocytes, macrophages, and fibroblasts.
Granulomatous inflammation. No discrete, rounded granulomas are present.
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