Dr. Pepe’s Diploma Casebook: CASE 145 – Art of interpretation – SOLVED!

Dear Friends,

as I told you last week, my plan for September is to show interesting cases seen during this summer.

Today I have prepared an Art of Interpretation case that I saw in July. Radiographs belong to a 90-year-old man with cardiac arrhythmia.

Most likely diagnosis:
1. Aortic aneurysm
2. Duplication cyst
3. Thymic tumor
4. Any of the above

Leave your thoughts in the comments and come back on Friday to see the answer!

Click here to see the answer:

Findings: PA and lateral radiographs show a left superior middle mediastinal mass adjacent to the aortic knob (A and B, white arrows). Healed fractures of the right clavicle and second left rib are visible (A, red arrows). Pacemaker in the left hemithorax.

Analysis of relevant findings:

1. Left middle mediastinal mass adjacent to the aortic knob
2. Old fracture right clavicle
3. Old fracture second left rib

Summing up the findings: Although the appearance of the mediastinal mass is non-specific, the proximity to the aortic arch raises the possibility of an aortic aneurysm.
The bone fractures indicate previous trauma. Especially relevant is the fractured second rib. The first and second ribs are well protected by the thoracic cage and breaking either of them needs a strong impact, significant enough to shear the thoracic aorta and lead to pseudoaneurysm formation.

Therefore, our tentative diagnosis should be traumatic pseudoaneurysm of aorta, followed by a request for enhanced CT to confirm the diagnosis.


Enhanced CT confirms a partially thrombosed aneurysm with a connection to the inferior aspect of the aortic arch (A-C, red arrows). On questioning, the patient mentioned an automobile accident fifteen years earlier. Because of his age, it was decided to control the aneurysm in six months’ time.

Final diagnosis: traumatic aortic pseudoaneurysm

Rupture of the thoracic aorta is not uncommon in severe blunt trauma, usually after high impact accidents or falls from a height of more than three meters (see case 1, below). About 85% of affected patients die immediately. The remaining 15% may survive if they arrive to the hospital in time to be treated.

A small percentage of cases are overlooked and patients survive without treatment. Over time a pseudoaneurysm develops at the point of rupture, most commonly the aortic arch.
About half these cases are discovered in routine chest examinations because of the typical location of the pseudoaneurysm around the aortic arch. Another diagnostic tip is that the patients are usually younger than patients with atherosclerotic aneurysms (see Case 2).

Discovering signs of previous trauma facilitates the diagnosis, especially when the first or second ribs are affected. After a history of severe trauma is elicited, the diagnosis is confirmed with enhanced CT. The pseudoaneurysm is usually located in the inferior aspect of the aortic arch, distal to the origin of the left subclavian artery.

Traumatic aortic pseudoaneurysms are infrequent, but I have seen several cases during my professional life. I am showing two representative cases to familiarize you with their radiographic appearance.


Chest radiographs of a 75-year-old male tourist with chest pain . A peripherally calcified mediastinal mass is projected over the aortic knob in the PA radiograph (A, arrow). The lateral view shows that the mass arises from the inferior aspect of the aortic arch (B, arrow).

Coronal and sagittal enhanced CT images demonstrate a calcified aneurysm arising from the inferior aspect of the aortic arch (C and D, arrows), distal to the origin of the left subclavian artery (E, circle). On questioning, the patient mentioned surviving a helicopter crash six years earlier. A diagnosis of traumatic pseudoaneurysm was made. The patient returned to his country of origin and was lost to follow-up.


42-year-old man with vague chest symptoms. A chest radiograph from another center (unavailable) showed a mediastinal mass with peripheral calcification. CT scout view yields the same finding (A, arrow).

Enhanced CT shows a large calcified aneurysm distal to the origin of the left subclavian artery (B and C, arrows). The rest of the aorta is normal. The patient had experienced an automobile accident ten years earlier. Traumatic pseudoaneurysm was proven at surgery.

Dr. Pepe’s teaching points:

Tips to suspect a traumatic aortic pseudoaneurysm in the chest radiograph:

1. Mediastinal mass around the aortic arch

2. Signs of previous trauma, especially fractures of the first or second ribs.

Abdominal #3 – Long case

A 70-year-old male presents to the Emergency Room with abdominal pain and distention. The patient has a history stage IV non-small cell lung cancer, chronic obstructive pulmonary disease, hypertension, severe dementia and recent deep venous thrombosis. He presents secondary to 2 days of poor appetite, diffuse abdominal pain, abdominal distention, and increasing dyspnea. He reports no bowel movements in last 2 days.

The decision was made to proceed with a CT of the abdomen and pelvis with intravenous and oral contrast. The following study was obtained.

Whats is the most likely diagnosis?

Diagnosis: High-grade small bowel obstruction due to internal hernia with small bowel pneumatosis and small volume pneumoperitoneum.

In cases with bowel obstruction, the radiologist should aim to identify the cause of the obstruction as early surgical reversal may be curative for the patient. One of the uncommon causes of small bowel obstruction includes internal hernias. This is a difficult diagnosis to make, and a few signs are may be useful to help identify it. Firstly, it is important to look at the overall distribution of the bowel loops. In this case, the distended bowel loops are abnormal in position, as they are within the pelvis as well as positioned anterior to the large bowel.

In this case, the duodenojejunal junction and ligament of Treitz are seen to the right of midline and are positioned inferiorly and posteriorly deep pelvis along the peritoneal reflection. In this case, the low position of the bowel loops may be due to a defect in the sigmoid mesocolon which would make the rare diagnosis of a sigmoid mesocolon hernia.

Most importantly are the ancillary features which make this case a surgical emergency. Firstly, pneumatosis intestinalis is seen within the small bowel wall:

Using the lung window, we are also able to notice subtle pneumoperitoneum:

In cases with suspected bowel ischemia, it is important to additionally look for gas within the portal venous system, which in this case was not present.

Due to multiple comorbidities, and upon further consultation with family and the patient, the decision was made not to operate and undergo conservative management.

Cáceres’ Corner Case 209 – SOLVED

Dear Friends,

welcome to the next season of the blog!

During September I will show cases that I have seen this summer. Today’s radiograph belong to a 23-year-old woman who couldn’t elevate her left arm more than twenty degrees.

What do you see?

Come back on Friday to see the answer!

Click here to see the answer

Findings: AP radiograph of the left shoulder shows numerous rounded calcifications projected over the scapula and humeral head (A, circle). The first diagnosis that comes to mind is osteopoikilosis but, given the patient’s symptoms, chondromatosis of the shoulder should be considered.

The dilemma is easily solved by taking a comparison view of the contralateral shoulder, which shows identical findings (B and C, circles).

The patient’s mother was a physician and very anxious. She insisted in taking a radiograph of the pelvis, which again shows the typical findings of osteopoikilosis
(D, circles).

Final diagnosis: unsuspected osteopoikilosis
Congratulations to Zehra who was the first to suggest the correct diagnosis.
Teaching point: remember the usefulness of comparison films in MSK imaging

P. S. This a warm-up case to facilitate your return to the Diploma cases. Next week will be more difficult!

Musculoskeletal #3 – Long case

Axial CT abdomen bone window

Axial CT abdomen soft tissue window

Where is the lesion?

Left iliac bone

What are the radiological characteristics/findings?

Large lytic lesion with wide zone of transition, cortical destruction, and large soft tissue component.
No specific matrix.

What is the differential diagnosis of an aggressive iliac bone lesion?

* Metastasis
* Plasmacytoma: solitary plasma cell tumor expansile lytic lesion with bone destruction and soft tissue component. Usually shows low signal intensity on T2 with variable post contrast enhancement. 
* Chondrosarcoma: malignant cartilage tumor destructive lytic lesion with intralesional rings and arcs calcification (chondroid matrix). High signal intensity on T2. 

What is the most likely diagnosis?