Musculoskeletal #19

54-year-old man with dorsolumbar irradiated left leg pain and paresthesias

What are the imaging findings?

CT: Slightly insufflating lytic lesion in the left pedicle, with thickened vertical trabeculae (“polka dot sign”) 
MRI: The lesions show high signal on T2 and STIR sequences, with small foci of T1 hyperintensity within the lesions suggesting fatty component. Soft tissue component with the same characteristics and avidly enhancing. Note the spinal canal secondary stenosis, cord displacement and compression

What is the most likely diagnosis

Aggressive vertebral hemangioma with soft tissue component

Dr. Pepe’s Diploma Casebook 169 – SOLVED

Dear Friends,

Presenting a new case of “Big little findings”. Preoperative chest radiograph for meniscus surgery in a 56-year-old woman.

What do you see?

Click here to see the answer

Findings: PA view shows a small right hemithorax. There is elevation of the right hemidiaphragm and a small hilum (A, red arrow). The findings are very suggestive of RLL lobectomy. The oblique fissure in the RLL represents the displaced minor fissure (A, white arrow). Previous CT shows a normal-size right lung with a ground-glass opacity in the RLL (B, arrow).

Final diagnosis: RLL lobectomy for adenocarcinoma of the lung

I am showing this case to discuss displacement of the lung fissures, an important finding that can indicate partial collapse of the underlying lobe. Usually, lobar collapse is detected because of the increased opacity of the lobe. Occasionally, the collapsed lobe retains much of its air, so a shift of the fissure may be the only sign of collapse.

A potential pitfall of fissure displacement is previous surgery, as seen in the case presented. In my experience, excluding previous surgery, aerated lobar collapse occurs mainly in the following conditions:

1. Inflammatory peripheral lung disease
2. Central lobar bronchial obstruction
3. Rounded atelectasis

NORMAL ANATOMY
The right minor fissure is visible in about 50% of chest radiographs as a straight horizontal line at the level of the right hilum (Fig. 1, A and B) The right and left major fissures are not visible in the PA film because their course is not tangential to the x-ray beam. (A, curved dotted lines). They are both visible as oblique lines in the lateral view (B).

Fig. 1
Fig. 2. PA radiograph showing the minor fissure (A, arrow). The lateral view shows both the right minor and major fissures (B, white arrows) and the upper portion of the left major fissure (B, red arrow)

Inflammatory lesions can cause scarring which diminishes the size of the affected lobe. TB is the most common cause in upper lobes. Bronchiectasis is the predominant cause in lower lobes. Both conditions can show an aerated lobe with loss of volume (Figs. 3-5).

Fig. 3. 68-year-old woman with previous history of TB. There is aerated partial collapse of RUL as evidenced by the elevated minor fissure (A and B, white arrows). Fibrotic changes are seen in the apex (A and B, red arrows). An incidental finding is calcification of breast prostheses.
Fig. 4. RLL collapse secondary to bronchiectasis. There is an oblique line at the right base (A, white arrow) that simulates an inferior accessory fissure. However, the right hilum is markedly low (A, red arrow), indicating loss of volume of RLL. Coronal CT shows marked RLL collapse with bronchiectasis, outlined by the displaced major fissure (B, arrow).
Fig. 5. 56-year-old man with previous TB. Lateral view shows forward displacement of the left major fissure (A, arrows), indicating partial collapse of LUL. PA radiograph depicts marked elevation of left hilum (B, arrow), secondary to fibrotic TB.

Central lobar bronchial obstruction is occasionally associated with aerated lobar collapse. It is thought to be due to collateral air ventilation through incomplete fissures (Figs. 6-7).

Fig. 6. Routine follow-up of an 82 y.o. man who underwent surgery for laryngeal carcinoma 10 years ago. PA view shows abnormal left hilum and blurring of the left cardiac contour (A, arrow). Lateral view shows marked forward displacement of the left major fissure (B, arrows) indicating severe LUL collapse.

Unenhanced axial CT confirms the marked LUL collapse (C, white arrow) secondary to endobronchial obstruction (C, red arrow). CT taken one year earlier shows an endobronchial lesion (D, red arrow) and discrete forward displacement of the major fissure (D,E, white arrows). These changes were overlooked. Surgical diagnosis: bronchogenic carcinoma

Fig. 8. Aerated RLL collapse in central carcinoma. PA radiographs shows a very low right major fissure (A, red arrow), better depicted in the cone down view (B, arrow). The left hilum is descended (A, white arrow). Bronchoscopy discovered a carcinoma of the RLL bronchus. The oblique line in the RUL corresponds to a scar.

Rounded atelectasis is a common cause of fissure displacement. It occurs secondary to spiral folding of the lung parenchyma when fixed by thickened pleura. The consequence is a peripheral rounded opacity in an aerated collapsed lobe. The volume loss, detected by the displaced fissure, avoids possible confusion with a true nodule in the plain film.

Fig. 9. Asymptomatic 49-year-old man with rounded atelectasis. Notice the visibility of the left major fissure, indicating LLL volume loss (A, arrows). Lateral view shows an ill-defined posterior opacity which corresponds to the rounded atelectasis (B, arrow).

Axial and sagittal CT confirm displacement of the left major fissure (C and D, white arrows), the small LLL, and the posterior rounded atelectasis (C, red arrow).

As a final thought, occasionally you may find fissure displacement without an apparent cause (Fig. 10).

Fig. 10. 92-year-old man, asymptomatic. PA radiograph shows downward displacement of the minor fissure (A, white arrow), major fissure (A, yellow arrow) and right hilum (A, red arrow). In a previous film four years earlier, the minor fissure (B, yellow arrow) and the right hilum (B, red arrow) were moderately descended. Since the patient was 92 y.o. and had no symptoms, his physician decided not to do a CT scan. My impression is that he has fibrotic changes in the RLL, which is not unusual in advanced age.


Follow Dr. Pepe’s advice:
1. A displaced fissure may be the only manifestation of aerated lobar collapse (always exclude previous surgery).

2. Most common causes:

a) Peripheral lobar inflammatory disease

b) Central bronchial obstruction

c) Rounded atelectasis

Musculoskeletal #13 – Flashcard

17-year-old patient with leg pain, worsening at night and improving with acetylsalicylic acid intake.

What are the imaging findings?

IMAGING FINDINGS:

Cortical bone reaction of the tibia mainly characterized by thickening with small lytic zone with central punctate calcification in the epicenter (nidus)

What is the most likely diagnosis?

Osteoid osteoma. Characteristic location, imaging and clinical presentation

Musculoskeletal #10 – Flashcard

29-year-old long-distance athlete presenting with 3 weeks of sciatica associated with an increase of running training loads

What do you see?

Click here to see the answer

IMAGING FINDINGS:

Unilateral sacral bone edema T2W, STIR hyperintensity associated with hypointense fracture line

DIAGNOSIS:

Fatigue stress fracture

TEACHING POINTS:

The sacrum is a frequent site for stress fractures
They can be related to overload occurring in a healthy bone as in this case, or related to osteoporosis (insufficiency stress fractures) in which cases they tend to be bilateral and “h- shaped”

Musculoskeletal #4 – Long case

Regarding the following X-Ray:

Frontal x-ray of the right hand

Where is the lesion?

Metaphysis of the base of the fourth middle phalanx.

What are the radiological characteristics/findings?

Expansile lytic lesion (bubbly appearance) with narrow zone of transition, no cortical break through, and no soft-tissue component.

What is the differential diagnosis?

Enchondroma: Enchondromas have variable imaging appearances but are typically lytic lesions with non-aggressive features. They could show chondroid calcifications (rings and arcs calcification). But in the hands and feet they are typically purely lytic with no matrix.
Eosinophilic granuloma: It mainly involves the diaphysis and does not cross the growth plates. It appears as punched out lytic lesions without sclerotic rim.  Imaging appearance in the long bones depends on the phase of the disease which is imaged. It can look aggressive in the initial phase. In the healing phase it can show solid benign periosteal reaction.
Fibrous dysplasia.Usually shows ground-glass matrix but may be completely lucent or sclerotic. Well-circumscribed lesions with no periosteal reaction may lead to premature fusion of growth plates leading to short stature in the lower limbs and bowing deformities (Shepherd’s Crook deformity of the femoral neck)

What is the most likely diagnosis?

Diagnosis: Enchondroma

Regarding the diagnosis…

What are the associated syndromes with multiple enchondromas?

Ollier disease: multiple enchondromas are usually  confined to one side of the body and limited to the limbs. There is increased risk of chondrosarcoma 

Maffucci syndrome: multiple enchondromas with soft-tissue haemangiomas

Emergency #14 – Flashcard

18-years-old male:
* Rigid abdomen and generalised tenderness
* Pain lower abdomen
* CRP 250

What do you see? Perforated appendicitis? What is your diagnosis?

Diagnosis Perforated sigmoid diverticulitis (Hinchey 3 or 4, peritonitis)

> Mesenterial fatty infiltration, free air bubbled outside bowel lumen.
> Also subdiaphragmal free air and free fluid.
> Notice enlarged reactive lymph nodes and peritoneal thickening and enhancement, indicative of peritonitis.
> Patient was operated, free faeces was found in the abdomen.

Hinchey classification of acute diverticulitis:
* Stage 1a: phlegmon
* Stage 1b: diverticulitis with pericolic or mesenteric abscess
* Stage 2: diverticulitis with walled off pelvic abscess
* Stage 3: diverticulitis with generalised purulent peritonitis
* Stage 4: diverticulitis with generalised faecal peritonitis