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Am Fam Physician. 2022;105(6):602-612

Related Letter: Case Report: Delayed Diagnosis of a High-Grade Spindle Cell Sarcoma Presenting as a Thigh Mass

This clinical content conforms to AAFP criteria for CME.

Author disclosure: No relevant financial relationships.

Soft tissue masses are a common presentation in family physician offices. Although most lesions, including lipomas, fibromas, and epidermal and ganglion cysts, are benign, rare lesions such as soft tissue sarcomas may have serious consequences. Masses that are deep to the fascia, are 5 cm in diameter or larger, grow rapidly, or present suddenly without explanation should prompt further workup. Imaging for concerning lesions may include ultrasonography, radiography, and sometimes magnetic resonance imaging with contrast. Ultrasonography can be used to assess size, depth, solid or cystic nature, and associated vasculature. Magnetic resonance imaging with contrast provides spatial orientation and delineation of soft tissue sarcomas from surrounding tissues such as muscles. Although less commonly used, computed tomography is an alternative in the initial evaluation of concerning masses and can assist with staging of retroperitoneal and visceral sarcomas. Incisional biopsy of a concerning soft tissue mass can also be useful for establishing a diagnosis. Lipomas and epidermal cysts may be excised if they are painful or if there is concern for malignancy. Because of the high mortality rate of soft tissue sarcomas, evaluation of high-risk masses with magnetic resonance imaging with contrast should be expedited with a referral to orthopedic oncology.

Most soft tissue masses in adults are benign.1,2 Because benign lipomas and epidermal cysts are less common in children, a greater percentage of these masses in children are malignant and account for nearly 20% of solid malignancies in this population.3
Clinical evaluation of soft tissue masses can be challenging because of nonspecific characteristics. The World Health Organization classifies most soft tissue neoplasms according to the tissue of origin. Common neoplasms include angiosarcoma, fibrosarcoma, leiomyosarcoma, liposarcoma, rhabdomyosarcoma, and synoviosarcoma.4 Other non-neoplastic masses may include ganglion cysts, hematomas, plantar fibromas, and vascular lesions. Cross-sectional imaging with magnetic resonance imaging (MRI), computed tomography (CT), or ultrasonography may be required to differentiate benign and malignant lesions.5 Table 11,642 and Table 216,23,34,35,4352 summarize the most common benign and malignant masses, respectively.
AbscessProgressive, subcutaneous, erythematous swelling with possible drainage6 Erythematous massUltrasonography showing focal collection vs. “cobblestoning” with cellulitis7 Incision and drainage with ultrasound guidance7
Consider antibiotics if recurrent or patient is immunocompromised810
Epidermal inclusion cystNodule under the skin11 Arise in areas with hair follicles
Pain and erythema if inflamed11
Mobile subcutaneous masses
Hallmark feature is central punctate1,12
MRI: well-defined T2 hyperintense lesions, may depend on presence of internal debris; ruptured cysts have a more varied appearance12 For mildly inflamed epidermal inclusion cysts, incision and drainage with culture12
Can consider excision if recurrent11
Ganglion cystArises from joint, ligament, or tendon injuries13 Most often on hands, wrists, feet, or ankles13,14 Ultrasonography to distinguish between cystic and solid masses, locate adjacent blood vessels, and distinguish between other diagnoses, including a ruptured Baker cyst and deep venous thrombosisObservation if no functional impairment15
Consider aspiration, steroid injection, or surgical excision if functional impairment or recurrent14,15
Hemangiomas/arteriovenous malformationsCapillary hemangiomas are the most common type12,16 Soft, compressible masses; diffuse blue or purple skin discoloration17 Radiography and ultrasonography may reveal lesions containing phleboliths and mixed echogenicity
MRI can demonstrate depth of the lesion16
Conservative treatment can include observation or intravascular sclerotherapy17
Surgical referral reserved for patients with symptomatic tumors17*
HematomaRapid onset
Should have an explanation (e.g., anticoagulation, trauma)
Fluctuant mass, sometimes with overlying ecchymosis18 Ultrasonography and MRI can show extent of the hematoma19 Mainly conservative treatment; evaluate if persisting or enlarging for more than one month20
Consider embolization if progressively expanding21
Intramuscular myxomaRare (0.12% of soft tissue tumors)
Typically occurs in large skeletal muscles
Most common between 40 and 70 years of age; slightly more common in women
Palpable mass, most common on the thigh and lower limb girdle22 MRI: T1 hypointense to muscle, high signal intensity on T2-weighted or fluid-sensitive sequencesSurgical excision in most cases22
LipomaMost common between 40 and 70 years of age and in patients who are obese16,23
Slightly more common in men24
Some genetic syndromes cause multiple lipomas
Superficial mass that is freely mobile with a doughy consistency24
Deep masses may involve muscle and move with muscle contraction24
Radiographs may appear normal24
Ultrasonography: often isoechoic to adjacent subcutaneous fat24
MRI is required for any deep mass or subcutaneous lesion ≥ 5 cm24
MRI demonstrates fat signal intensity 24
Monitoring for asymptomatic lipomas
Consider excision for symptomatic or painful masses, or for cosmetic reasons24
Lymphangioma: capillary, cavernous, or cysticAppears at birth or by 2 years of age
Pain is uncommon unless infection is present
Disfigurement can be significant25
Seen on the neck and axilla
Soft on palpation
Respiratory compromise is the most serious complication25
Chest radiography may be useful in identifying mediastinal extension or pleural effusions
Ultrasonography: hypoechoic, multilocular cystic masses25
CT: cystic lymphangioma; thicker septations are delineated
Observation only in the absence of symptoms
Excision is the standard treatment
Recurrence can be 27% and mortality about 2%25
Intralesional sclerotherapy is first-line treatment for macrocystic lymphangiomas26
Morton neuroma (peripheral nerve sheath tumor)27 Sensation of a “pebble in the shoe” or burning in toes distal to the neuroma27 No visual clues to neuroma
Mulder click test (dorsiflexing the foot and squeezing the metatarsals produces a clicking sound)
Radiography to rule out other sources of foot pain
Ultrasonography can be used to identify a neuroma and guide injection
MRI: neuroma seen on T1 axial slice28
Wide toe box shoes
Cortisone injections
Surgical excision
Mucous cystFinger swelling, pain, tenderness, decreased range of motion
80% occur between 50 and 70 years of age29
Twice as likely in women than men29
Approximate prevalence: thumb 18%, second finger 26%, third finger 38%, fourth finger 9%, fifth finger 8%29
Nail changes
Translucent mass adjacent to the nail bed30
Dermoscopic examination has reduced need for ultrasonography and radiography 30 Surgical excision yielded the highest cure rate (mean of 95%)
Second-line: sclerotherapy and cryotherapy
Third-line: corticosteroid injections, expression of cyst content31
Pilar cyst90% occur on the scalp32
Most common after 15 years of age
Slightly more common in women32
Swelling over the scalp
Area of alopecia
Well-defined, oval mass
Occurs in areas with dense hair follicles32
Imaging not usually warranted
Ultrasonography: internal echogenic foci with demonstrated calcification, cholesterol crystals, or both; no blood flow in the lesion33
MRI: homogeneous, isointense signal on T1-weighted images; homogeneous, hyperintense signal on T2-weighted images32
CT: well-defined, hypodense masses with occasional calcification34
If benign, treat with simple local excision
If malignant, refer for wide local excision and possible Mohs surgery32
Plantar fibromaMild pain that worsens after walking or standing for longer periods
Bilateral in 20% to 50% of cases
May have had trauma to the area or family history35
Palpable nodule or focal thickening along the plantar fasciaUltrasonography: fusiform nodules that are hypoechoic to isoechoic without intrinsic vascularity (comb sign)36
MRI: well-defined mass, isointense to muscle on T1-weighted images; well-defined, broad base at the superficial fascia demonstrates a fascial tail from extension of the tumor along the fascial plane
Can locally recur35
Intralesional corticosteroid injection
Consider subtotal fasciectomy with wide excision if conservative therapies are ineffective36
Myositis ossificansCommon after trauma37 Painful, rock-like mass
Commonly affects quadriceps femoris and brachialis muscles
Organized calcification within the muscle38
MRI: classic hyperintense mass, calcifications may appear on T2-weighted images
Radiography or CT: early detection with typical peripheral zonal ossification37
Self-limiting with prolonged resolution common
Consider referral for debilitating cases
Schwannoma in the footSwelling along the flexor surface
Most common between 30 and 40 years of age
Men and women affected equally39
Account for 5% of benign soft tissue tumors40
May present similarly to Morton neuroma
Clinical presentation depends on tumor size and location41
Motor or sensory disturbances along the flexor surface
Radiograph findings are often negative
MRI shows lesions along a neurovascular bundle; a nerve may enter or exit a mass
Small asymptomatic tumors may be followed clinically
If symptomatic, patient should be referred for biopsy with histologic examination and surgical excision41
Tenosynovial giant cell tumorSwelling most often in hands or feet
Common between 30 and 50 years of age
Slightly more common in women
Second finger is most often affected42
Rounded or lobulated mass appears to encase the surface of a tendonRadiography: bony erosions
Ultrasonography: small tumor with blood flow that does not attach to tendon
MRI: lesion has low signal compared with muscle on T1-weighted images; hemosiderin deposition on T2-weighted images41
Surgical resection
Recurrence rate as high as 15%40
Dermatofibrosarcoma protuberansMedian age of presentation is 20 to 59 years
Equally common in men and women43
Lesion is slow-growing and present for years
Account for 1% of all soft tissue sarcomas
Pink plaque44
Approximate prevalence of nodules: trunk 50% to 60%, upper limbs 25%, head and neck 10% to 15%44
Untreated lesions may ulcerate or bleed
Ultrasonography shows tentacle-like projections, hypervascularity45
MRI or CT is useful for recurrent disease or large and atypical primary lesions45
Referral to orthopedic oncology for core needle biopsy and excision
Wide excision with negative margins
Mohs surgery for lesions that have wide margins or for cosmetic reasons43,44
Leiomyosarcoma46,47 Patients may report abdominal or back pain
More common in adults older than 55 years
In younger age groups, leiomyosarcoma is more common than liposarcoma
Enlarging mass on the limbs but can also occur on the head, neck, and retroperitoneum
Palpable abdominal mass or symptoms of bowel obstruction46
CT with contrast shows heterogeneous mass
MRI can be used for patients with contrast allergies or for further investigation of muscle or bone involvement if equivocal on CT
Referral to orthopedic oncology for core needle biopsy and surgery46
LiposarcomaAccounts for about 17% of all soft tissue sarcomas48
Painless, rapidly enlarging soft tissue mass
Most common between 50 and 60 years of age
Equally common in men and women49
Rare in children; in young children, more likely to be lipoblastoma50
Fullness or asymmetry, mobile unless attached to bone, nontender
Lymph node examination is required
Radiography shows fat-attenuation or soft-tissue masses; calcifications or ossification in 10% to 32% of cases23
MRI findings can vary significantly depending on subtype and grade50,51
Large tumor size with thick septa and nodular or patchy nonadipose components are indicative of well-differentiated liposacromas51
Referral to orthopedic oncology for core needle biopsy and resection
RhabdomyosarcomaPainful cervical mass
Commonly seen in children younger than 10 years
Rare in adults52
Approximate prevalence: head and neck region near orbit 40%, urinary or reproductive organs 30%, extremities 15%, other locations 15%47 Ultrasonography is the first-line imaging study for investigating soft tissue masses in children34
Imaging findings vary depending on location
Referral to orthopedic oncology
SynoviosarcomaSlow growing
Most common in adults 30 to 40 years of age16,47
Mass size typically between 3 cm and 10 cm
May be painful
Radiography shows calcification in 33% of cases35
Ultrasonography: heterogeneous mass with areas of necrosis and eccentric calcifications with variable vascularity47
MRI: well-demarcated mass, isointense to muscle on T1-weighted images47
Extrinsic bone erosion in 11% to 20% of cases
Diagnosis can be delayed because of slow growth
Referral to orthopedic oncology for core needle biopsy and resection

History and Physical Examination

Malignant masses may grow over weeks to years depending on the aggressiveness of the tumor.5 Both benign and malignant masses can be painless, but those that present suddenly without explanation or are firm, deep, and adhere to surrounding structures are more concerning for malignancy.5 Sarcomas do not fluctuate in size, whereas masses such as hemangiomas and ganglion cysts often do. 

Based on strong evidence, lesions that are 5 cm in diameter or larger should be evaluated with advanced imaging or the patient referred because of a higher risk of malignancy.5,52 However, smaller size does not exclude malignancy because approximately 10% of malignant soft tissue masses are smaller than 5 cm when diagnosed.53 Because of the high mortality rate of soft tissue sarcomas and the potential to miss a small sarcoma, any mass that is not definitively diagnosed should be closely monitored or the patient referred to orthopedic oncology.5 

Examination includes inspection of the skin and palpation of the mass to assess its depth, mobility, and adherence to deeper structures. Measurement can be difficult, but using a 4- to 5-cm golf ball as a reference can be helpful. 

Familiarity with the specific features that can differentiate soft tissue masses can be useful for diagnosis and avoiding unnecessary treatment. When the diagnosis is uncertain, family physicians should refer patients to a multidisciplinary treatment center. Table 3 lists coding resources for the use of point-of-care ultrasonography and other skin procedures in the evaluation of soft tissue masses. Figure 1 is an algorithm for the evaluation of soft tissue masses.

Imaging Studies


A detailed ultrasound examination of soft tissue masses often uses a high-resolution (9 to 17 MHz) linear transducer. Ultrasonography can assist in evaluating tumor characteristics such as size, margins, vascularity, cystic nature, and encroachment into surrounding tissues.2,54 Advantages of using traditional or point-of-care ultrasonography include low cost, no radiation exposure, and the ability to evaluate compressibility and assess real-time blood flow. Point-of-care ultrasonography can be used for follow-up in the clinic to evaluate changes.


The accuracy of plain radiography for diagnosing soft tissue tumors is limited. Radiography should be considered before advanced imaging to evaluate for bony involvement and intratumoral calcifications in osteogenic or synoviosarcomas.55

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