Dr. Pepe’s Diploma Casebook: CASE 125 – SOLVED

Dear Friends,

Today I am showing radiographs of an asymptomatic 57-year-old man in whom a pulmonary nodule was discovered.

Diagnosis:

1. Probably benign
2. Probably malignant
3. Indeterminate
4. It is extrapulmonary

Check the images below, leave your thoughts in the comments section, and come back on Friday for the answer.

Click here for the answer

Findings: The nodule has a hazy lateral border (A, white arrow) because it is adjacent to the chest wall. The rounded shape goes against an extrapulmonary lesion, which should be more ovoid. The most relevant finding in the plain film is the presence of coarse calcification within the nodule (A, red arrow), which is a sign of benignancy. Coronal and axial CT confirm an intrapulmonary nodule with popcorn calcification (B and C, white arrows), as well as fat within the nodule (C, red arrow).

Final diagnosis: RUL hamartoma

I am presenting this case to review the second most common presentation form of lung carcinoma, a solitary pulmonary nodule (SPN), which occurs in up to 30% of cases. SPN is defined as a well- or poorly-defined rounded opacity, measuring up to 3 cm in diameter. A lesion larger than that is considered a mass, which is very likely malignant.

SPNs are not uncommon and are usually an incidental finding in chest radiographs. The main goal is to differentiate benign from malignant nodules as accurately as possible. In this presentation, I would like to share with you a few useful tips to approach the solitary pulmonary nodule in the plain chest radiograph.

Tip #1. Be sure to exclude pseudonodules before you start the work-up. Remember that up to 20% of suspected SPNs are false nodules, which may be transient or stable. Transient nodules are due to acute pulmonary conditions that simulate a nodular lesion (Figs. 1 and 2).

Fig. 1. 59-year-old woman with fever and an RLL infiltrate with a peripheral nodule (A, arrow). After treatment, the false nodule has disappeared (B).

Fig. 2. 75-year-old man with an acute pulmonary embolism treated with anticoagulants. During his stay at the hospital, a round nodule appeared in the left lung (A and B arrows), showing high density in the CT study (C, arrow). It was interpreted as a spontaneous hematoma related to the treatment. The nodule progressively decreased in size and disappeared three months later, leaving a linear scar (D and E, arrows) (Case courtesy of Eva Castañer MD).

Stable pseudonodules are usually simulated by extrapulmonary structures, such as nipples, skin lesions, rib fractures, or bone islands (Figs. 3-5).

Fig. 3. Preoperative chest film in a 45-year-old man with inguinal hernia. A small nodule is seen in the left middle lung (A, arrow). The lateral view shows that the nodule is located in the anterior chest wall (B, arrow).

Fig. 4. False nodule due to calcified hypertrophic cartilage at the first costochondral union (A, arrow). These are fairly common in elderly persons and can be recognized by their increased opacity and proximity to the costochondral area. 3-D reconstruction confirms the diagnosis (B, arrow).

Fig. 5. Fracture of the second left rib simulating a pulmonary nodule (A, arrow). Axial CT confirms the diagnosis (B, arrow).

Tip #2. Pulmonary nodules are often missed. Be sure to look for them in the blind areas of the chest. Most are hidden in the upper lobes, where their reported miss rate is nearly 60% (Fig. 6).

Fig. 6. 52-year-old man with asthenia. There is a nodule in the left apex (A and B, arrows) that was overlooked in the chest radiograph. CT performed to exclude a thymoma discovered the nodule (C, arrow). Diagnosis: carcinoma

Pulmonary nodules may hide in the central or peripheral areas in the PA radiograph (Fig. 7). Needless to say, the lateral view is crucial to detect SPNs hidden in the PA view (Fig. 8).

Fig. 7. 76-year-old man with acute chest pain. PA film shows a nodule in the right costophrenic sinus (A, arrow) that was overlooked. The descending aorta is elongated. Enhanced coronal CT shows an aortic dissection (B, red arrow). The nodule did not enhance (B, white arrow). Needle biopsy established the diagnosis of hamartoma.

Fig. 8. Asymptomatic 65-year-old man. PA chest film (A) is unremarkable. Lateral chest film shows a small nodule in the anterior clear space (B, arrow), confirmed with CT (insert, arrow). Diagnosis: adenocarcinoma

Tip #3. The most reliable criterion in plain films to determine our management of an SPN is whether or not it is growing in size. Therefore, it is essential to compare with previous films, when available. A nodule that has grown in the interval is probably malignant and should be acted upon (Fig. 9).

Fig. 9. Indeterminate nodule in the right lung (A, arrow). Plain film one year earlier shows the nodule (B, arrow), considerably smaller and missed at that time. Diagnosis: adenocarcinoma

If no growth is evident over a period of 24 months, the nodule is likely benign and can be monitored by CT follow-up.

Fig. 10. Well-defined benign right lung nodule (A and B, arrows), unchanged in a 24-month period.

Tip #4. In plain films, visible calcium in an SPN is a reliable sign of benignancy (Fig. 11). This sign often fails because a high KV technique tends to “burn” the calcium, making it difficult to identify when present (Fig. 12).

Fig. 11. TB granulomas in two different patients. In A, central bulls-eye calcium is visible (A, arrow). In the second patient, a heavily calcified nodule is seen (B, arrow).

Fig. 12. Hamartoma with popcorn calcification (A, arrow), poorly visible in the chest radiograph and better depicted in the cone-down view (B, arrow).

As was mentioned earlier, a high kV technique tends to “burn” calcium, and even heavily calcified nodules may not be recognized in the plain radiograph. For this reason, CT should be performed when calcium is suspected and conventional radiography fails to demonstrate it (Fig. 13).

Fig. 13. 48-year-old woman with an apparently non-calcified RUL nodule (A, arrow). Coronal CT show that the nodule is heavily calcified (B, arrow).


Follow Dr. Pepe’s advice:

1. Rule out pseudonodules before you start the work-up.

2. Search for missed nodules in blind areas of the chest, especially in the apices.

3. Look at previous films to determine whether or not a nodule is growing.

4. Detecting calcium in a nodule is a reliable sign of benignancy.

16 thoughts on “Dr. Pepe’s Diploma Casebook: CASE 125 – SOLVED

  1. AP film showing typical metastatic nodule , lateral x ray shows extensive involvement of lesion possibly primary lung carcinoma.

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  2. I think it’s extrapulmonary nodule, because on lateral view the lesion shows “pregnancy sign”. Moreover, one side of the nodule is blurred, ill defined, while the other is well defined.

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  3. In my opion it’s an extrapulmonary lesion because of the “indistinct border sign”. On the lateral view it is located in the posterior mediastinum.

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  4. It is most likely extrapulmonary due its appearnce in lateral view however sometimes we can nit assessed extrapulmonary frim pleural based lesions.

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  5. intrapulmonary nodules form an acute angle with the lung edge (extrapulmonary an obtuse one) – and looking and the lateral film I’m starting to believe that this is a tricky case and it’s actually intrapulmonary;)

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