Dr. Pepe’s Diploma Casebook: CASE 121 – SOLVED!

Findings: PA radiograph shows an abnormal mediastinal contour (A, white arrows). In addition, the right lung is smaller than the left and its vasculature is diminished. The clue to the diagnosis lies in identifying a tubular shadow in the right lower lung (A, red arrow), which represents an anomalous venous return (scimitar sign). Coronal CT shows a smaller right lung and the scimitar vein (B, red arrow), typical of this malformation.

Diagnosis: congenital hypogenetic lung syndrome with scimitar vein

This week I intend to present additional signs in chest imaging. In a sense, recognizing signs is a sort of Aunt Minnie approach: once we are certain that a specific sign is present, we expedite the path to the correct diagnosis.

Today I will focus on signs of the lung compartment.
The first one is the scimitar sign.

The scimitar sign is the hallmark of hypogenetic right lung syndrome, in which there is agenesis of one or two pulmonary lobes. Partially anomalous return of the RLL veins is present in 80% of cases. The vessel is seen as a widening tubular shadow, originating the term scimitar syndrome.
The vein is not seen on plain films in half the cases.

Importance of the sign: It helps to diagnose congenital hypoplasia of the lung and avoids confusing this condition with more serious disorders.

Sometimes the scimitar vein is clearly visible (Fig. 1). On other occasions, it is partially hidden by the lung changes and we have to look carefully for the vein to suggest the correct diagnosis (Fig. 2).

QUIZ: 57-year-old man with chest pain and moderate fever.

Diagnosis:

1. Pneumonia
2. Pulmonary infarct
3. Pleural fluid
4. None of the above

Findings: PA radiograph shows a triangular pulmonary opacity at the right costophrenic angle with an indistinct convex border (A, arrow), a feature known as Hampton’s hump. In the appropriate clinical circumstances, this sign is highly suggestive of pulmonary infarction. Enhanced coronal CT confirms a thrombus in the lower pulmonary artery (B, arrow).

Diagnosis: pulmonary embolism with Hampton´s hump

HAMPTON’S HUMP
On plain radiographs, pulmonary infarcts are peripheral in location. When located in the costophrenic angle, they show an indistinct convex border (Hampton’s hump) that differentiates them from pleural fluid, which has a concave border.

Importance of the sign: In the appropriate clinical setting, Hampton’s hump is a reliable sign of pulmonary infarct and indicates enhanced CT to investigate pulmonary emboli.

It is not uncommon for infarcts to occur in the posterior costophrenic sulcus. In these cases, the Hampton’s hump may not be visible in the PA radiograph, but be very obvious in the lateral projection (Fig. 4).

Enhanced CT confirms the infarct in the posterior costophrenic sinus (C and D, white arrows). A thrombus is seen in the distal artery (D, red arrow).

In asymptomatic patients, diaphragmatic hernias may simulate a Hampton’s hump and should be ruled out (Fig. 5). Remember that the diaphragm is a frontier organ, and lesions arising from below may mimic chest lesions.

QUIZ: 56-year-old man with cough and fever.

What is the probability of malignancy?

1. Low
2. 50/50
3. High
4. Can’t tell

Findings: PA radiograph shows a segmental infiltrate in the RUL (A, arrow). The lateral view shows concavity of the minor fissure (B, white arrow), with convexity at the hilar level (B, red arrow), creating a Golden sign. Malignant disease is very likely.

CT confirms a central mass occluding the RUL bronchus (C and D, arrows). PET/CT shows marked uptake of the mass (E, arrow).

Diagnosis: carcinoma of RUL with Golden sign

The Golden sign is usually seen on posteroanterior chest radiographs. It occurs when a large central mass produces partial collapse of the right upper lobe. As the lobe collapses, the minor fissure is visible as a concave triangular opacity that represents the collapsed lobe (A and B, white arrows). The central mass forms a convex bulge at the origin of the lobe (A and B, red arrows). The combination of these findings resembles a reverse S shape.
 Although initially described in right upper lobe collapse, the Golden sign can be applicable to atelectasis involving any lobe.

Importance of this sign: In adults, it is highly suggestive of bronchial carcinoma.

The Golden sign is usually indicative of carcinoma (Fig. 6), although sometimes it results from non-malignant enlarged lymph nodes (Fig. 7).

Although the Golden sign is usually found in the RUL, it may also occur in other lobes (Fig. 8).

The Golden sign was overlooked and the patient was treated for pneumonia. Five months later the proximal mass was larger (C, arrow). Unenhanced CT shows the mass (D, arrow), confirmed to be malignant at bronchoscopy.

Follow Dr. Pepe’s advice:

1. Discovering a scimitar sign helps to diagnose congenital hypogenetic lung and exclude other significant disease.

2. Hampton’s hump is a reliable sign of pulmonary infarction in the adequate clinical setting.

3. The Golden sign is a good indicator of malignancy.