Elastofibroma dorsi is a benign fibro-elastic pseudotumor that develops on the deep surface of the inferior scapular tip (infraseratus region), between the thoracic fascia and the serratus anterior/latissimus dorsi muscles. It is an important differential diagnosis of chest wall soft tissue masses. Typically occurs in women over 55 years of age (5-13 times more common in women). Autopsy series report prevalence of 11-24%, most of which are clinically silent. Ten to 66% of lesions are bilateral — bilateral subscapular location is pathognomonic and no other soft tissue tumor has such a characteristically specific location. Alternating layers of fat and fibrous tissue ('lenticular pattern') create the diagnostic finding on CT and MRI. The vast majority are detected incidentally and require no treatment; in symptomatic patients (pain with shoulder movement, clicking sensation), surgical excision is curative with rare recurrence.
Age Range
50-85
Peak Age
70
Gender
Female predominant
Prevalence
Uncommon
The pathogenesis of elastofibroma dorsi is not fully elucidated, but the most accepted theory is the repetitive mechanical trauma and friction hypothesis. The continuous sliding movement of the inferior scapular tip over the thoracic fascia (especially during arm abduction and flexion movements) causes chronic mechanical irritation. This repetitive microtrauma triggers reactive fibroproliferation in the connective tissue between the periosteum and deep fascia. Histologically, the lesion consists of degenerated elastic fibers (so-called 'elastoid' fibers, products of abnormal elastogenesis), collagen, and mature adipose tissue — fragmentation and abnormal regeneration of elastic fibers form the basis of the pathology. The alternation of fat and fibrous tissue layers directly determines the imaging findings: on CT, fat (-50 to -100 HU) and soft tissue (+30 to +50 HU) densities are seen in alternating bands; on MRI, fat components appear hyperintense on T1 while fibrous components appear hypointense — this alternating pattern is termed the 'lenticular imaging pattern.' The tendency for bilaterality (up to 66% in autopsy series) is consistent with anatomic predisposition — both scapulae are subjected to the same biomechanical stress. A genetic predisposition component has also been suggested as familial cases have been reported, though no specific genetic mutation has been identified.
The lenticular pattern, the signature finding of elastofibroma dorsi, is the characteristic imaging finding created by alternating layers of fat and fibrous tissue within the subscapular mass on CT and MRI. Fat bands show linear or globular distribution, creating a 'lens-shaped' appearance within the fibrous stroma. This pattern combined with bilateral subscapular location is pathognomonic, and no other soft tissue tumor has such a characteristic location + morphology combination.
On non-contrast CT, a well-defined or slightly irregular-margined soft tissue mass is seen on the deep surface of the inferior scapular tip, located between the thoracic wall and latissimus dorsi/serratus anterior muscles. The characteristic feature is alternating areas of fat density (-50 to -100 HU) and soft tissue density (+30 to +50 HU) — this pattern is described as the lenticular (lens-shaped) appearance. Fat streaks typically show linear or globular distribution within fibrous stroma at muscle density. Mass size is usually 5-10 cm and may fill the entire potential space between the scapula and thoracic wall. Bilateral detection rate is reported as 10-66% in clinical series; evaluation of both sides on CT is important. Calcification is absent.
Report Sentence
Bilateral subscapular masses measuring ___ x ___ cm and ___ x ___ cm on the deep surface of the inferior scapular tips, containing alternating bands of fat and soft tissue density (lenticular pattern), consistent with elastofibroma dorsi.
On contrast-enhanced CT, elastofibroma dorsi shows minimal or no enhancement. Mild enhancement may be seen in fibrous components, but this is at a similar level to surrounding muscle tissue and does not create a distinct enhancement pattern. Fat components do not enhance and maintain their negative density. The absence of significant enhancement is an important criterion for differentiation from malignant soft tissue tumors (such as soft tissue sarcomas, metastases). Although irregular mass margins may suggest malignancy, absent enhancement combined with bilateral subscapular location is sufficient for diagnosis.
Report Sentence
No significant enhancement is seen in the lesions on contrast-enhanced series, with minimal enhancement in fibrous components similar to surrounding muscle.
On T1-weighted images, elastofibroma dorsi appears heterogeneous. The main body consists of fibrous stroma showing signal isointense or slightly hypointense to muscle. Within this fibrous stroma, hyperintense linear or globular fat areas isointense to subcutaneous fat are scattered. Fat distribution is typically in linear bands, giving the lesion a lenticular (lens-shaped) appearance. This pattern is best visualized on T1 because T1 contrast maximizes the difference between fat (short T1, bright signal) and fibrous tissue (long T1, dark signal). The lesion is typically unencapsulated, in contact with surrounding structures (scapula, ribs, muscles), and while generally well-defined may sometimes show irregular margins.
Report Sentence
On T1-weighted images, the subscapular mass contains linear/globular hyperintense fat streaks isointense to subcutaneous fat within muscle-isointense fibrous stroma (lenticular pattern).
On T2-weighted images, elastofibroma dorsi shows heterogeneous signal. Fibrous stroma shows signal isointense or slightly hyperintense to muscle, while fat components show hyperintense signal. Because fibrous tissue shows more similar signal to muscle on T2, the fat-fibrous contrast is reduced compared to T1; however the alternating pattern is still discernible. On STIR sequence, significant signal suppression is seen in fat components — this is important for confirming macroscopic fat. Fibrous components remain at similar signal to muscle on STIR. Perilesional edema is typically absent — this is an important differential criterion as perilesional edema is common in malignant soft tissue tumors.
Report Sentence
The lesion shows heterogeneous signal on T2-weighted images, with significant signal suppression in fat components on STIR sequence.
On gadolinium-enhanced MRI, elastofibroma dorsi shows minimal or no enhancement. Mild enhancement at a level similar to surrounding muscle may be seen in fibrous components, but no significant or aggressive enhancement pattern is present. Fat components do not enhance. This minimal enhancement pattern reflects the benign, hypovascular nature of the lesion and is an important distinguishing feature from malignant soft tissue tumors (prominent heterogeneous enhancement, perilesional enhancement). On diffusion-weighted images (DWI), no significant diffusion restriction is expected — ADC values typically reflect the mixed signal of fat and fibrous tissue.
Report Sentence
No significant enhancement is seen in the lesions on contrast-enhanced series; this finding is consistent with benign, hypovascular character.
On ultrasound, elastofibroma dorsi typically appears heterogeneous. The main body consists of fibrous stroma isoechoic or slightly hypoechoic to muscle, with scattered echogenic (bright) fat foci within this stroma. This alternating echogenicity pattern is the ultrasonographic equivalent of the lenticular pattern on CT and MRI. The lesion is imaged on the deep surface of the inferior scapular tip, between ribs and latissimus dorsi muscle. Margins are usually indistinct with gradual transition to surrounding muscles. Dynamically, the lesion can be visualized sliding beneath the scapula during shoulder movements ('gliding sign'). On Doppler ultrasound, vascular flow is generally not detected or is at minimal level.
Report Sentence
A heterogeneous mass containing echogenic fat foci within muscle-isoechoic stroma is seen in the subscapular region, with no significant vascular flow on Doppler.
On FDG PET-CT, elastofibroma dorsi typically shows low-grade or no FDG uptake. SUVmax values are typically 1.0-2.5 — comparable to physiologic muscle activity level. In some cases, mildly increased uptake may be seen, which can cause false-positive malignancy suspicion — particularly problematic in unilateral or non-bilateral lesions. However, the combination of bilateral subscapular location, alternating fat-soft tissue density, and low SUV largely confirms the diagnosis. PET-CT is not typically used as the primary diagnostic modality for elastofibroma, but it may be incidentally detected on PET-CT performed for other indications.
Report Sentence
No significant FDG uptake is seen in bilateral subscapular masses on PET-CT (SUVmax: ___), consistent with metabolically inactive benign lesion (elastofibroma dorsi).
Criteria
Symmetric or asymmetric masses at inferior tips of both scapulae; most common form (10-66% bilateral), diagnosis is definitive and biopsy is not needed
Distinct Features
Bilateral location alone establishes the diagnosis; diagnostic confidence is higher than unilateral lesions; size asymmetry may exist but lenticular pattern is present on both sides
Criteria
Unilateral subscapular mass; lenticular pattern present but diagnosis less definitive without bilateral support; small or early lesion should be sought on contralateral side
Distinct Features
Differential diagnosis requires caution; lipoma, liposarcoma, desmoid tumor, and elastic fibrosarcoma should be considered; follow-up or biopsy may be needed; lenticular pattern should be confirmed with thin-section CT/MRI
Criteria
Pain with shoulder movement, clicking sensation, scapular crepitus; rare (symptoms in <50% of patients); more common in large lesions; indication for surgical excision
Distinct Features
Imaging findings are identical to asymptomatic form; clinical symptoms guide surgical decision-making; post-surgical recurrence is rare (<5%); symptoms typically occur in large lesions (>5 cm)
Distinguishing Feature
Lipoma forms a homogeneous fat-density mass (entirely negative HU), lacking the alternating fat-fibrous pattern of elastofibroma; lipoma is encapsulated and well-defined
Distinguishing Feature
Liposarcoma shows prominent enhancement, non-lipomatous components, and perilesional edema; well-differentiated liposarcoma may mimic elastofibroma but thick septa (>2 mm), nodular enhancing components, and diffusion restriction create differentiation
Distinguishing Feature
Desmoid tumor (aggressive fibromatosis) forms homogeneous fibrous mass — does not contain fat components; marked T2 hypointensity (fibrosis), shows prominent enhancement; not limited to scapula, may show infiltrative growth into surrounding tissue
Distinguishing Feature
Rib metastasis shows bone destruction (lytic, blastic, or mixed), may form subscapular soft tissue mass but lacks fat-fibrous alternation; malignancy history, prominent enhancement, and osteodestruction create differentiation
Urgency
routineManagement
conservativeBiopsy
Not NeededFollow-up
no-follow-upElastofibroma dorsi is a benign, non-neoplastic pseudotumor with no risk of malignant transformation. When diagnosed by bilateral subscapular location and lenticular pattern, no biopsy or follow-up is needed. Asymptomatic patients require no treatment and patient reassurance is sufficient. In symptomatic patients (pain, clicking, functional limitation), surgical marginal excision is curative with recurrence rate less than 5%. In unilateral lesions where diagnostic confidence is lower, careful evaluation of the contralateral side and short-term follow-up (6-12 months) if necessary should be recommended. When incidentally detected on PET-CT, diagnosis can be made by low FDG uptake and characteristic CT morphology, avoiding unnecessary biopsy.
Elastofibroma dorsi is a benign lesion with no risk of malignant transformation. Diagnosis can be made based on typical location and imaging findings; biopsy is generally not needed. Surgical excision may be performed in symptomatic patients (pain, restricted movement). Asymptomatic lesions require no follow-up. Due to the possibility of bilateral occurrence (10-66%), the contralateral side should also be evaluated.