Case 9


Section 1

Look at images 1 and 2.

Image 1

 

1. Are the nodules diffuse or patchy?

2. What is their distribution?

Answers

vascnod

Image 2

Find nodules along the interlobar fissure in the right lung.

Find nodules at the peripheral pleura.

Find centrilobular nodules.

Note that the above nodules are not marked.

Find a nodule at the end of a vessel in the right lung of image 1 and in the left lung of image 2.

vascnod


Section 2

Gross Appearance

The lesions in this slice of lung correspond to those shown above. Compare the size of the nodules in the lower lung to that in the upper lung.

Are they larger or smaller?

Can you give a reason for your answer?

Answers

 


Section 3: Histologic Findings

Histologically, the nodular lesions in this disease are often not well-formed because of a poor host response.

 

Compare the amount of cytoplasm in the rounded collection of cells indicated by the thin arrows to the amount in the surrounding cells.

Which cells have more cytoplasm?

What types of cells are in the rounded nodule?

What type of cell is indicated by the thick arrow?

What is the histologic diagnosis?

Answers

Differential diagnosis of random nodules on HRCT: Diagnoses include miliary tuberculous, fungal, or occasionally viral infections and hematogenous metastasis (particularly from thyroid, kidney, and breast). Langerhans' cell histiocytosis, sarcoidosis, and silicosis are common causes of nodules, but in these cases the nodules are rarely diffuse and haphazard.

Histologic differential diagnosis: Diagnoses to be considered include infectious granulomas (mycobacterial and fungal), sarcoidosis, and hypersensitivity pneumonia.

Diagnosis: Miliary tuberculosis

Summary of diagnostic features of miliary tuberculosis on HRCT

See Case Study 32 for other examples of tuberculosis (several are linked to the Discussion).

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1. Diffuse

2. Random. Note how these nodules are distributed haphazardly throughout the lungs, along the pleura and fissures, at the ends of small arteries (peripheral bronchovascular), and also in a centrilobular location. Random nodules are typically uniformly distributed bilaterally. No single anatomic location predominates, as in this case.

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1. The lesions at the top of the lung are slightly larger than those at the bottom.

2. Compared to the bottom of the lung, less blood supply and poorer lymphatic clearance mechanisms at the top of the lung make host defenses less effective there.

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Nodule at the end of a vessel

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Compare the amount of cytoplasm in the rounded collection of cells indicated by the thin arrows to the amount in the surrounding cells.

Which cells have more cytoplasm?

The cells delimited by arrows

What types of cells are in the rounded nodule?

Mostly epithelioid histiocytes (with prominent cytoplasm), some lymphocytes

What type of cell is indicated by the thick arrow?

A multinucleated giant cell

What is the histologic diagnosis?

Ill-defined, non-necrotizing granuloma

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