Sternal tumors are primary or secondary neoplasms developing in the sternum (breastbone). The most common malignant tumors of the sternum are metastases (from breast, lung, kidney, thyroid); among primary tumors, chondrosarcoma is most common, followed by myeloma/plasmacytoma, lymphoma, osteosarcoma, and Ewing sarcoma. Primary benign tumors (osteochondroma, enchondroma, hemangioma) are rare. CT typically shows a lytic or expansile sternal lesion, soft tissue mass, and retrosternal extension. Blastic pattern suggests metastasis (prostate, breast) or osteosarcoma. MRI best evaluates soft tissue extension, relationship to mediastinal structures, and bone marrow involvement. Chondroid matrix calcification (ring-and-arc) indicates chondrosarcoma; permeative destruction pattern indicates aggressive tumor. Most sternal tumors require aggressive surgery (partial/total sternectomy + reconstruction); biopsy is critical for histologic diagnosis before surgery.
Age Range
30-80
Peak Age
55
Gender
Male predominant
Prevalence
Rare
The pathogenesis of sternal tumors varies by tumor type. Primary chondrosarcoma develops from malignant chondrocyte transformation of the sternal cartilage components (especially manubrium and sternal-cartilage junction regions) — a significant portion of the sternum consists of hyaline cartilage, creating susceptibility to cartilage-origin neoplasias. Chondrosarcoma in the sternum is typically low-to-intermediate grade and produces chondroid matrix causing ring-and-arc calcification on CT — the calcification pattern is an irregular repetition of the endochondral ossification process. Multiple myeloma/plasmacytoma results from monoclonal proliferation of plasma cells in bone marrow — myeloma cells secrete osteoclast-activating factors (RANKL, MIP-1alpha, DKK1) creating lytic destruction and inhibiting new bone formation; therefore appearing as cold areas on scintigraphy (no osteoblastic activity). Metastatic sternal involvement occurs via hematogenous spread — the sternum's rich bone marrow vascular sinusoidal architecture provides suitable environment for metastatic cell adhesion. In osteosarcoma, malignant osteoid (bone matrix) production causes high-density amorphous calcification/ossification on CT — different from the organized ring-and-arc pattern of chondrosarcoma. Ewing sarcoma develops from proliferation of small round cells via EWSR1-FLI1 fusion gene and shows aggressive bone destruction characterized by 'onion-skin' periosteal reaction.
The signature imaging finding of sternal tumor is a lytic or expansile bone lesion in the sternum with presternal and/or retrosternal soft tissue mass. Retrosternal extension determines relationship to mediastinal structures and is critically important for surgical planning. This triad (bone destruction + soft tissue mass + retrosternal extension) has high sensitivity for sternal neoplasm and requires urgent further workup (biopsy, staging).
On non-contrast CT, sternal tumor typically presents as a lytic (bone-destructive) or expansile (bone-expanding) lesion in the sternum. In lytic lesions, cortical destruction, defect formation, and sternal contour irregularity are seen. In expansile lesions, the sternum expands and remaining cortex thins ('balloon' pattern — typical of chondrosarcoma and plasmacytoma). Soft tissue mass typically extends from the anterior (presternal) and/or posterior (retrosternal) surface of the bone lesion. Retrosternal extension is critical for evaluating relationship to mediastinal structures (heart, pericardium, great vessels, esophagus). Destruction pattern indicates tumor type: geographic destruction (sharp margin, sclerotic border) = slow-growing; moth-eaten = intermediate aggressive; permeative = highly aggressive. Presence and pattern of matrix calcification (ring-and-arc = chondroid, amorphous = osteoid, absent = myeloma/metastasis) guides diagnosis.
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A lytic/expansile bone lesion measuring ___ x ___ cm in the ___ (manubrium/body/xiphoid) region of the sternum with accompanying ___ x ___ cm soft tissue mass is seen, retrosternal extension ___ (present/absent).
On contrast-enhanced CT, the enhancement pattern of sternal tumors varies by tumor type. In chondrosarcoma, septa and peripheral areas enhance while chondroid matrix-containing lobules do not — 'septal enhancement' pattern is characteristic. Myeloma/plasmacytoma shows homogeneous or mildly heterogeneous enhancement. In metastases, enhancement varies depending on primary tumor (hypervascular metastasis: renal, thyroid = prominent enhancement; hypovascular metastasis: lung, breast = mild enhancement). In osteosarcoma, heterogeneous enhancement is seen — mineralized matrix areas do not enhance, viable tumor tissue shows prominent enhancement. In Ewing sarcoma, homogeneous to mildly heterogeneous enhancement is seen. Enhancement of retrosternal soft tissue extension and relationship to mediastinal structures should be evaluated.
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The sternal lesion shows ___ (homogeneous/heterogeneous/septal) enhancement pattern on contrast-enhanced series; retrosternal soft tissue extension is related to ___.
On T1-weighted images, sternal tumor is seen as a low-to-intermediate signal intensity lesion replacing normal bone marrow fat (T1 hyperintense). Normal sternal bone marrow in adults is predominantly fat tissue, showing hyperintense signal isointense to subcutaneous fat on T1. Tumor infiltration eliminates fat signal, creating hypointense (chondrosarcoma, myeloma, metastasis) or isointense (lymphoma) signal. Degree of T1 hypointensity correlates with tumor cellularity — highly cellular tumors appear darker. Retrosternal soft tissue extension is evaluated as obliteration of mediastinal fat planes on T1. Chondrosarcoma shows low signal on T1 because hyaline cartilage's high water content causes long T1. Hemorrhagic areas may show T1 hyperintensity in subacute phase (methemoglobin).
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On T1-weighted images, a lesion with ___ signal intensity replacing normal bone marrow fat signal is seen in the ___ region of the sternum.
On T2-weighted images, signal intensity of sternal tumors varies significantly by tumor type. Chondrosarcoma shows markedly hyperintense T2 signal — reflecting high water content of hyaline cartilage and pathognomonic combined with lobular morphology. Myeloma/plasmacytoma shows intermediate-to-high T2 signal. Metastases show variable signal depending on primary tumor. In osteosarcoma, mineralized areas are T2 hypointense, viable tumor areas hyperintense — heterogeneous appearance. Ewing sarcoma shows intermediate-to-high T2 signal and prominent peritumoral edema. STIR sequence best evaluates bone marrow edema and peritumoral spread — all tumor types appear hyperintense on STIR with increased contrast from normal marrow fat suppression. Retrosternal soft tissue extension is best evaluated on T2.
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The sternal lesion shows ___ (markedly hyperintense/intermediate hyperintense/heterogeneous) signal on T2-weighted images, with ___ (lobular morphology/diffuse infiltration/mineralized components).
On FDG PET-CT, malignant sternal tumors generally show high FDG uptake. Osteosarcoma and Ewing sarcoma show the highest SUVmax values (usually >10). Chondrosarcoma is grade-dependent — low-grade chondrosarcomas show low-to-intermediate SUVmax (2-5), high-grade/dedifferentiated chondrosarcomas show high SUVmax (>8). In myeloma, uptake is usually high but may be diffuse. Metastases show variable uptake depending on primary tumor. PET-CT plays a critical role in metastatic staging (distant metastasis, lymph node involvement) and biopsy planning (targeting most active area). In treatment response evaluation (post-neoadjuvant chemotherapy), metabolic activity change has prognostic significance. Benign lesions (hemangioma, enchondroma) typically show low or no FDG uptake.
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Increased metabolic activity is seen in the sternal lesion on FDG PET-CT (SUVmax: ___); ___ (systemic metastasis/lymph node involvement/additional bone lesion) ___ (detected/not detected).
On bone scintigraphy (99mTc-MDP), uptake of sternal tumors varies significantly by tumor type. Tumors showing osteoblastic activity (osteosarcoma, blastic metastasis, chondrosarcoma) show increased uptake ('hot lesion'). Myeloma/plasmacytoma shows decreased uptake ('cold lesion') or may appear normal because it inhibits osteoblastic activity — this is the most important limitation of bone scintigraphy in myeloma and whole-body MRI or PET-CT should be preferred. Lytic metastases generally show increased uptake (due to surrounding reactive bone formation) but purely aggressive lytic metastases may be cold. Bone scintigraphy is useful for whole-body screening but limited in characterizing sternal lesions.
Report Sentence
On bone scintigraphy, ___ (increased/decreased/normal) radiopharmaceutical uptake is seen in the sternum; additional bone lesion ___ (detected/not detected).
Criteria
Expansile lytic lesion + ring-and-arc calcification (chondroid matrix) + markedly hyperintense T2 signal; predilection for manubrium and sternal-cartilage junctions; usually low-to-intermediate grade
Distinct Features
Ring-and-arc calcification is pathognomonic; lobular morphology best seen on T2 MRI; chemotherapy/radiotherapy ineffective — treatment is wide surgical resection; 5-year survival >90% in low-grade
Criteria
Single (plasmacytoma) or multiple (myeloma) lytic lesions; NO matrix calcification; expansile or permeative destruction; COLD on bone scintigraphy; serum/urine protein electrophoresis abnormal
Distinct Features
Cold lesion on bone scintigraphy is characteristic of myeloma (osteoblast inhibition); 'punched-out' lytic pattern; no sclerotic border on CT; diffuse marrow infiltration on MRI T1 hypointense, T2/STIR hyperintense
Criteria
Known primary malignancy history; lytic (lung, kidney, thyroid) or blastic (prostate, breast) or mixed pattern; usually accompanied by multiple bone lesions; primary tumor type determines enhancement and destruction pattern
Distinct Features
Metastasis is the most common overall cause of sternal malignancy; primary tumor screening should be performed even for single sternal lesion; PET-CT is critical for staging and primary tumor search; biopsy needed for histologic confirmation and primary tumor typing
Criteria
Osteosarcoma: amorphous osteoid matrix calcification, permeative destruction, large soft tissue mass, young-middle age; Ewing: permeative destruction, onion-skin periosteal reaction, large soft tissue mass, pediatric/young adult
Distinct Features
Both are high-grade aggressive tumors; neoadjuvant chemotherapy + wide surgical resection is standard; PET-CT critical in treatment response evaluation; EWSR1-FLI1 fusion gene diagnostic in Ewing
Distinguishing Feature
Rib chondrosarcoma locates at costochondral junction; sternal chondrosarcoma in sternum; ring-and-arc calcification common to both — location is distinguishing
Distinguishing Feature
Multiple myeloma is accompanied by widespread lytic lesions (skull, vertebrae, pelvis, long bones); solitary sternal lesion may be plasmacytoma; serum protein electrophoresis and bone marrow biopsy establish definitive diagnosis
Distinguishing Feature
Metastasis has known primary malignancy history; usually accompanied by multiple bone lesions; PET-CT enables primary tumor detection and staging; biopsy confirms concordance with primary tumor type
Distinguishing Feature
Mediastinal lymphoma may mimic sternal invasion with retrosternal extension; in lymphoma primary mass is mediastinal with secondary bone invasion, in sternal tumor primary bone lesion exists; diffuse homogeneous enhancement and intermediate T2 signal suggest lymphoma
Urgency
urgentManagement
surgicalBiopsy
NeededFollow-up
3-monthSternal tumors require multidisciplinary approach due to their biological behavior and surgical complexity. Biopsy is mandatory for histologic diagnosis — core biopsy (thick needle) or incisional biopsy is preferred; biopsy tract must be included in surgical resection plan. For primary tumors, treatment is wide surgical resection (partial or total sternectomy + chest wall reconstruction). In chondrosarcoma, chemotherapy and radiotherapy are generally ineffective; surgery with negative margins is the most important prognostic factor. In osteosarcoma and Ewing sarcoma, neoadjuvant chemotherapy + surgery + adjuvant chemotherapy is standard. In myeloma/plasmacytoma, systemic therapy (chemotherapy, immunotherapy) is primary; surgery plays limited role. In metastases, treatment may be systemic therapy, radiotherapy, or palliative approach depending on primary tumor and stage. When retrosternal extension is present, careful surgical planning (cardiothoracic surgeon collaboration) is required for mediastinal structure preservation. Follow-up imaging is performed with CT or MRI at 3-month intervals for first 2 years, then at 6-month intervals.
The first step in evaluating sternal tumors is distinguishing primary from secondary. In patients with known malignancy, metastasis should be the primary consideration and systemic staging with PET-CT should be performed. Primary sternal tumors (chondrosarcoma, osteosarcoma, plasmacytoma) generally require wide surgical resection — with chest wall reconstruction. Radiation therapy is effective for plasmacytoma. Chemotherapy is the primary treatment for lymphoma. Biopsy is mandatory for diagnosis — can be performed under CT or US guidance. Multidisciplinary tumor board evaluation is recommended.