Pictorial essay.

ZATTAR-RAMOS, L.C.1*

LEÃO, R.V.1

CAVALCANTI, C.F.A.1

BORDALO-RODRIGUES, M.1

LEITE, C.C.1

CERRI, G.G.1

HOSPITAL SÍRIO-LIBANÊS,

São Paulo – SP, Brazil. *luzattar@gmail.com

1Department of Radiology

ER_024 EDUCATIONAL REVIEW

▶ DISCLOSURE PARAGRAPHS:

- The authors of this educational review declare no relationships with any companies, whose products or services may be related to the subject matter of the article. - The authors state that this work has not received any funding.

▶ INTRODUCTION:

- Sternal abnormalities are commonly seen in clinical practice.

- In addition to the numerous anatomical variations and congenital anomalies, the sternum and sternoclavicular joints can be affected by various pathological conditions such as trauma, infection, tumors, degenerative and inflammatory changes.

- This study aims to demonstrate and illustrate such conditions, as the knowledge of its characteristics and imaging findings are essential for correct diagnosis and patient management.

▶ DISCUSSION:

- Sternum injuries are common and should be properly recognized and characterized; using different imaging methods we will illustrate the variations of normality, congenital abnormalities and characteristic radiographic findings of sternal lesions highlighting: psoriatic arthritis, inflammatory osteitis, SAPHO syndrome, neoplastic, traumatic and degenerative lesions.

▶ ANATOMY: STERNUM:

*MANUBRIUM: superior central (jugular) notch and 2 lateral fossae that articulate with the clavicles. Also articulates with the 1o and 2o ribs and the body of the sternum. - Atachments: sternohyoideus, sternothyroideus, subclavius, pectoralis major, transversus thoracis and sternocleidomastoideus muscles.

*BODY OF THE STERNUM: articulates with the manubrium, xiphoid process and with the 2o through 7o ribs. - Attachments: transversus thoracis and pectoralis major.

*XIPHOID PROCESS: cartilaginous or ossified / fused to the sternal body. - Attachments: rectus abdominis, diaphragm and transversis thoracis.

MANUBRIUM

BODY OF THE

STERNUM

XIPHOID PROCESS

Flat bone, with 3 parts:

Convex anteriorly and concave posteriorly

▶ ANATOMY: STERNUM: *STERNOCLAVICULAR JOINT: synovial joint, connects the axial skeleton to upper extremity. - Components: anterior sternoclavicular, interclavicular and costoclavicular ligaments, articular disk and articular cavities.

*MANUBRIOSTERNAL JOINT: synchondrosis covered with hyaline cartilage and separated by a disk of fibrocartilage (dorsal and ventral ligaments), forming the sternal angle. - Conversion to synovial joint in 30% (disk absorption) / Ossification of the disk in 10% (synostosis).

*XIPHISTERNAL JOINT: synchondrosis, usually ossifies to form a synostosis.

STERNOCLAVICULAR JOINT

MANUBRIOSTERNAL JOINT

XIPHISTERNAL JOINT

1. SUBCLAVIUS

2. STERNOCLEIDOMASTOIDEUS

3. PECTORALIS MAJOR

4. RECTUS ABDOMINIS

5. STERNOHYOIDEUS

6. STERNOTHYROIDEUS

7. TRANSVERSUS THORACIS

8. DIAPHRAGM and TRANSVERSIS THORACIS

▶ ANATOMY: STERNUM: JUGULAR NOTCH

CLAVICULAR NOTCH

1st RIB ARTICULATION

2st RIB ARTICULATION 2nd

3nd

4nd

5nd 6nd 7nd

COSTAL NOTCHES

TRANSVERSE RIDGES

STERNAL ANGLE

1 2

3

3

3

5

6

7

4 8

*ATACHMENTS:

I. CONGENITAL ABNORMALITIES / ANATOMICAL VARIANTS

III. TRAUMA

II. DEGENERATIVE CHANGES

V. INFLAMMATORY CHANGES

VI. INFECTION

VII. OTHERS

IV. TUMORS

*SPECTRUM OF THE STERNAL LESIONS:

- Sternum is displaced posteriorly and, as a consequence, the ribs protrude anteriorly. - Genetic component (45% familial) - May result in decreased cardiac stroke volume and decreased total lung capacity.

*TILTED STERNUM: sternum that is oriented obliquely, determining unilateral irregularity / asymmetry of the chest wall

I. CONGENITAL ABNORMALITIES / ANATOMICAL VARIANTS: *CASE 1: PECTUS EXCAVATUM: most common congenital deformity of the sternum.

15-years-old male patient: (A) Lateral chest radiograph; (B) Sagittal CT image; (C) Axial CT image: showing

vertical orientation of the anterior aspect of the ribs and the depressed (red arrows) and tilted sternum

(white arrow).

A B C

- PECTUS INDEX: axial CT/MR: dividing the transverse diameter of the chest by the anteroposterior diameter. Normal: 2.56 (+-0.35). Surgical > 3.25.

*CASE 2: PECTUS EXCAVATUM TREATMENT:

15-years-old male patient: Axial CT image before (A) and after (B) 5 minutes of vacuum; (C) Posteroanterior chest radiograph image; (D) CT reconstruction:

showing the depressed sternum (with a pectus index of 5.1 before and 3.9 after the vacuum) and the vacuum bell system where a suction cup is used to create a vacuum

at the chest wall.

A

B

C D

I. CONGENITAL ABNORMALITIES / ANATOMICAL VARIANTS:

- The sternum in pectus carinatum is displaced anteriorly. - More than 30% are associated with scoliosis; 25% familial. - Clinical manifestations include exercise intolerance / shortness of breath.

*PECTUS INDEX : 1.42-1.98.

*CASE 3: PECTUS CARINATUM:

16-years-old male patient: (A) Axial CT image and (B) Lateral chest radiograph;;

showing manubrial and upper sternal protrusion

(red arrows).

I. CONGENITAL ABNORMALITIES / ANATOMICAL VARIANTS:

A B

*CASE 4: STERNALIS MUSCLE: - Uncommom anatomic variant. - Superficially and perpendicular to the pectoralis major muscle, paralel to the sternum. - Runs from the infraclavicular region inferiorly to the caudal aspect oh the sternum. *Reports of the sternalis muscle simulating breast nodules in mammography.

I. CONGENITAL ABNORMALITIES / ANATOMICAL VARIANTS:

56-years-old male patient: (A) Axial CT image, (B) Coronal CT reconstruction and (C) Sagittal CT image: showing bilateral sternalis muscle

(red arrows).

A

B C

II. DEGENERATIVE CHANGES:

95-years-old female patient. (A) Sagittal; (B) Coronal and (C) Axial CT images: showing degenerative changes in

right sternoclavicular joints with bone sclerosis, narrowing of the joint space and gas within the joint space

(red arrows).

C

A B

*CASE 5: OSTEOARTHRITIS: STERNOCLAVICULAR JOINT: - Most common abnormality affecting the sternoclavicular joint. - Also occur in the manubriosternal joint.

II. DEGENERATIVE CHANGES: *CASE 6: OSTEOARTHRITIS: COSTOSTERNAL JOINT:

81-years-old male patient. (A) Axial MRI T1-WI; (B) Axial MRI STIR WI; (C) Coronal CT

image; (D) Axial CT image: showing degenerative changes in the right costosternal

joint with osteophytes and sclerosis in CT images (white arrows), and soft-tissue swelling of the joint and intra-articular

effusion in MRI (red arrows).

A

B

A

B C

D

II. DEGENERATIVE CHANGES: *CASE 7: OSTEOARTHRITIS: MANUBRIOSTERNAL JOINT:

71-years-old male patient. (A) Sagittal CT image and (B) Coronal CT image: showing degenerative changes in the manubriosternal joint with sclerosis of both articular surfaces and a subchondral cyst on the body of the sternum (red arrows).

A B

III. TRAUMA: *CASE 8: STERNAL FRACTURE:

- High-energy trauma – most commonly on the sternal body. - IMPORTANT: high frequency of associated injuries: pulmonary and cardiac trauma, craniocerebral injuries, ribs, thoracic and lumbar spinal fractures.

52-years-old female patient after a motor vehicle accident. (A and C) Coronal and (B) Sagittal

reconstruction CT images: showing manubrium fracture with soft tissue swelling (red arrows).

A B C

IV. TUMORS: *CASE 9: METASTASIS:

- Most common neoplasms of the sternum: METASTASIS. - Direct infiltration or hematogenous spread. - Common sources: lung, breast, thyroid, kidney, colon and hematologic malignancies.

62-years-old male patient with multiple myeloma. (A) Axial, (B) Coronal and (C) Sagittal CT images: showing a large ill-defined lytic lesion in the manubrium (red arrows). Another lesion with the same characteristics is seen in the 6th left lateral costal arch (white arrow), with cortical

destruction.

A B C

IV. TUMORS: *CASE 10: METASTASIS:

69-years-old male patient with thymic carcinoma and myeloproliferative disease. (A) Axial, (B) Sagittal and (C) Coronal CT images: showing a multiple blastic lesions in the sternum (red arrows).

A B C

- Apperance may be lytic (multiple myeloma) or blastic / sclerotic (prostate or breast cancer).

IV. TUMORS: *CASE 11: OSTEOSARCOMA:

22-years-old female patient who previously underwent radiation therapy . MRI images: (A) Axial T2-WI; (B) Axial T1-WI; (C) Coronal T1-WI; (D) Coronal T2-WI; (E) Coronal enhanced

T1-WI; (F) Sagital T1-WI; (G) Sagittal T2-WI; (H) Sagittal enhanced T1-WI: showing an osseous lesion with mixed signal /predominantly hyoerintense on T2-WI with heterogeneous

enhancement after intravenous contrast administration (red arrows).

- More commonly in older patients. - Secondary malignancy following radiotherapy.

A

B C D E

F G H

IV. TUMORS: *CASE 12: PLASMOCYTOMA:

- Localized proliferation / solitary mass of neoplastic monoclonal plasma cells. - Diffuse proliferetion: MULTIPLE MYELOMA

70-years-old female patient with multiple myeloma. CT images: (A and B) Axial, (C and D) Coronal and (E and F) Sagittal reconstructions: showing an intramedullary expansile lesion of the sternum with cortical bone erosion (red arrows).

A B

C D E F

V. INFLAMMATORY CHANGES: *CASE 13: CRYSTAL INDUCED ARTHROPATHY:

- GOUT: rare: typically well marginated paraarticular erosions, and appositional bone deposition with expansion of bone ends - PSEUDOGOUT: CALCIUM PYROPHOSPHATE DIHYDRATE CRYSTAL DEPOSITION: occasional: typically chondrocalcinosis and tophaceous pseudogout formation.

93-years-old female patient.

(A and B) Axial CT images: showing

crystal deposition in the

sternoclavicular joint (red arrows).

A B

V. INFLAMMATORY CHANGES: *CASE 14: SERONEGATIVE ARTHRITIS: PSORIATIC ARTHRITIS:

- Seronegative arthritides may affect the manubriosternal and sternoclavicular joints. - Common radiographic fidings: Erosions or fusion of the manubriosternal joint and sternoclavicular joint hyperostosis.

35-years-old female patient with psoriatic arthritis. MRI

Sagittal (A) T1-WI, (B) T2-WI and (C) enhanced T1-WI:

showing cortical erosion of the manubriumsternal joint with cortical bone sclerosis (low

signal intensity on both T1 and T2 images: white arrows) and

joint enhancement after intravenous contrast

administration (red arrow).

A B C

V. INFLAMMATORY CHANGES: *CASE 15: SAPHO SYNDROME:

- SAPHO: synovitis, acne, palmoplantar pustulosis, hyperostosis, and osteitis - Wide spectrum of aseptic neutrophilic dermatoses with aseptic osteoarticular lesions. - The sternoclavicular joint is most frequently affected (65%-90%).

52-years-old female patient with psoriatic arthritis. MRI Coronal (A) T1-WI, (B) T2-WI and (C) enhanced T1-WI: showing joint erosion and bone marrow edema of the sternoclavicular joint (red arrows) and an arthrosynovial cyst (white arrow).

A B C

V. INFLAMMATORY CHANGES: *CASE 16: TIETZE SYNDROME:

- Painful costochondritis of unknown cause – mainly in young women. - Characterized by mineralized and swollen costal cartilage.

A B C

30-years-old female patient with left sternoclavicular joint pain. CT (A) Sagittal, (B) Coronal and (C) Axial images: showing mineralized and sclerotic bone of the left sternoclavicular joint (red arrows).

V. INFECTION: IATROGENIC *CASE 17: POST STERNOTOMY:

- Primary osteomyelitis of the sternum is uncommon. - Related to intravenous drug abuse, immune deficiency states, hemoglobinopathy.

A B

C

78-years-old female patient with secondary osteomyelitis after median sternotomy and myocardial revascularization. CT (A-B) Sagittal and (C-D) Axial images: showing erosive changes of the sternum (white arrows), soft tissue edema and fluid collection (red arrows).

D

- Complications after sternotomy is rare. - Include: dehiscence, nonunion, secondary osteomyelitis /mediastinitis.

V. OTHERS: POST OPERATORY *CASE 18: STERNOTOMY DEHISCENCE:

A B

C

78-years-old female patient with 20 days history of sternotomy and myocardial revascularization. CT (A and B) Coronal and (C) Axial

images: showing sternal dehiscence with displacement of

the wires (red arrows).

V. OTHERS: *CASE 19: MYONECROSIS:

24-years-old male patient with sternal pain after excercise. MRI (A and B) Axial T1-WI ,(C) Coronal T-WI and (D) Coronal enhanced T1-WI: showing heterogeneous peripheral enhencement with central necrosis of the pectoralis major sternal insertion (red arrows).

A

B C D

- Myopathy involving infarcted muscle. - Causes: idiopathic, diabetic, post-traumatic, crush, ischaemia, rhabdomyolisis.

V. OTHERS: *CASE 20: PAGET DISEASE:

A B

75-years-old male patient with Paget disease. (A) Coronal and

(B) Sagittal CT images: showing mixed lytic and

sclerotic changes involving the stenum. Classic findings

include: osteolysis, trabecular coarsening, cortical thickening,

and osseous expansion (red arrows).

- Chronic skeletal disorder characterized by abnormal and excessive remodeling of bone. - Abnormal osseous resorption /apposition: variable clinical and imaging manifestations.

▶ CONCLUSION:

*To achieve accurate and timely diagnoses that facilitate the management and appropriate treatment, radiologists should be

familiar with the appearances of the diseases that may affect the sternum.

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