EDUCATIONAL REVIEW ER_024

Pictorial essay.

ZATTAR-RAMOS, L.C.1* LEÃO, R.V. 1 CAVALCANTI, C.F.A.1 BORDALO-RODRIGUES, M.1

1 LEITE, C.C. HOSPITAL SÍRIO-LIBANÊS, 1 São Paulo – SP, Brazil. CERRI, G.G. *[email protected]

1Department of Radiology

▶ 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 and sternoclavicular 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: Flat , with 3 parts:

*MANUBRIUM: superior central (jugular) notch and 2 lateral fossae that articulate with the MANUBRIUM clavicles. Also articulates with the 1o and 2o and the body of the sternum. - Atachments: sternohyoideus, sternothyroideus, subclavius, pectoralis major, transversus thoracis and sternocleidomastoideus muscles. BODY OF *BODY OF THE STERNUM: articulates with the THE manubrium, and with the 2o STERNUM through 7o ribs. - Attachments: transversus thoracis and pectoralis major.

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

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

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

*XIPHISTERNAL JOINT: synchondrosis, XIPHISTERNAL JOINT usually ossifies to form a synostosis. ▶ ANATOMY: STERNUM: JUGULAR NOTCH

*ATACHMENTS: CLAVICULAR NOTCH 2 5 1 1. SUBCLAVIUS 1st 6 3 ARTICULATION

2. STERNOCLEIDOMASTOIDEUS nd st 2 2 RIB ARTICULATION

3. PECTORALIS MAJOR STERNAL 3 ANGLE 3nd 4. RECTUS ABDOMINIS COSTAL NOTCHES 4nd TRANSVERSE 5. STERNOHYOIDEUS 3 RIDGES 7 6. STERNOTHYROIDEUS 5nd 6nd 7. TRANSVERSUS THORACIS 7nd

4 8 8. DIAPHRAGM and TRANSVERSIS THORACIS *SPECTRUM OF THE STERNAL LESIONS: I. CONGENITAL ABNORMALITIES / ANATOMICAL VARIANTS

II. DEGENERATIVE CHANGES

III. TRAUMA

IV. TUMORS

V. INFLAMMATORY CHANGES

VI. INFECTION

VII. OTHERS I. CONGENITAL ABNORMALITIES / ANATOMICAL VARIANTS: *CASE 1: PECTUS EXCAVATUM: most common congenital deformity of the sternum. - 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 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 I. CONGENITAL ABNORMALITIES / ANATOMICAL VARIANTS: *CASE 2: PECTUS EXCAVATUM TREATMENT: - PECTUS INDEX: axial CT/MR: dividing the transverse diameter of the chest by the anteroposterior diameter. Normal: 2.56 (+-0.35). Surgical > 3.25.

A

C D

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. B I. CONGENITAL ABNORMALITIES / ANATOMICAL VARIANTS: *CASE 3: PECTUS CARINATUM: - 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.

16-years-old male patient: (A) Axial CT image and (B) Lateral chest radiograph;; showing manubrial and upper sternal protrusion (red arrows).

A B I. CONGENITAL ABNORMALITIES / ANATOMICAL VARIANTS: *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.

A

56-years-old male patient: (A) Axial CT image, (B) Coronal CT reconstruction and (C) Sagittal CT image: showing bilateral sternalis muscle (red arrows). B C II. DEGENERATIVE CHANGES: *CASE 5: OSTEOARTHRITIS: STERNOCLAVICULAR JOINT: - Most common abnormality affecting the sternoclavicular joint. - Also occur in the manubriosternal joint.

C

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). A B II. DEGENERATIVE CHANGES: *CASE 6: OSTEOARTHRITIS: COSTOSTERNAL JOINT:

A D B A 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). B C II. DEGENERATIVE CHANGES: *CASE 7: OSTEOARTHRITIS: MANUBRIOSTERNAL JOINT:

A B

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). 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).

C A B 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.

A B C 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. IV. TUMORS: *CASE 10: METASTASIS: - Apperance may be lytic (multiple myeloma) or blastic / sclerotic (prostate or breast cancer).

A B C

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). IV. TUMORS: *CASE 11: OSTEOSARCOMA: - More commonly in older patients. - Secondary malignancy following radiotherapy.

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).

F G H

A

B C D E IV. TUMORS: *CASE 12: PLASMOCYTOMA: - Localized proliferation / solitary mass of neoplastic monoclonal plasma cells. - Diffuse proliferetion: MULTIPLE MYELOMA

A B

C D E F 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). 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%).

A B C 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). V. INFLAMMATORY CHANGES: *CASE 16: TIETZE SYNDROME: - Painful costochondritis of unknown cause – mainly in young women. - Characterized by mineralized and swollen .

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.

C

A B D 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). V. OTHERS: POST OPERATORY *CASE 18: STERNOTOMY DEHISCENCE: - Complications after sternotomy is rare. - Include: dehiscence, nonunion, secondary osteomyelitis /mediastinitis.

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). A B V. OTHERS: *CASE 19: MYONECROSIS: - Myopathy involving infarcted muscle. - Causes: idiopathic, diabetic, post-traumatic, crush, ischaemia, rhabdomyolisis.

A

B C D

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). V. OTHERS: *CASE 20: PAGET DISEASE: - Chronic skeletal disorder characterized by abnormal and excessive remodeling of bone. - Abnormal osseous resorption /apposition: variable clinical and imaging manifestations.

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).

A B ▶ 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. ▶ BIBLIOGRAPHY: 1. Aslam M, Rajesh A, Entwisle J, Jeyapalan K. MRI of the sternum and sternoclavicular joints. Br J Radiol. 2002;75(895):627- 634. 2. Becker NJ, Arthur A. Psoriatic arthritis affecting the manubriosternal joint. Arthritis Rheum. 1986;29(8):1029-1031. 3. Ehara S. Manubriosternal joint: Imaging features of normal anatomy and arthritis. Jpn J Radiol. 2010;28(5):329-334. doi:10.1007/s11604-010-0438-9. 4. Franquet T, Giménez A, Alegret X, Sanchis E, Rivas A. Imaging findings of sternal abnormalities. Eur Radiol. 1997;7(4):492-497. doi:10.1007/s003300050190. 5. Goodman LR, Teplick SK, Kay H. Computed the Normal Tomography oh the Normal Sternum. AJR Am J Roentgenol. 1983;141(August):219-223. 6. Haecker FM, Mayr J. The vacuum bell for treatment of pectus excavatum: An alternative to surgical correction? Eur J Cardio-thoracic Surg. 2006;29(4):557-561. doi:10.1016/j.ejcts.2006.01.025. 7. Hatfield MK, Gross BH, Glazer GM, Martel W. Computed tomography of the sternum and its articulations. Skeletal Radiol. 1984;11(3):197-203. doi:10.1007/BF00349494. 8. Restrepo CS, Martinez S, Lemos DF, et al. Imaging appearances of the sternum and sternoclavicular joints. Radiographics. 2009;29(3):839-859. doi:10.1148/rg.293055136. 9. Stark P, Jaramillo D. CT of the Sternum. AJR Am J Roentgenol. 1990;147(July):72-77. 10. Yekeler E, Tunaci M, Tunaci A, Dursun M, Acunas G. Frequency of sternal variations and anomalies evaluated by MDCT. Am J Roentgenol. 2006;186(4):956-960. doi:10.2214/AJR.04.1779. 11. Theodorou DJ, Theodorou SJ, Kakitsubata Y. Imaging of Paget Disease of Bone and Its Musculoskeletal Complications : Review. Am J Roentgenol. 2011;(June):64-75. doi:10.2214/AJR.10.7222.