Soft Tissue Tumors

Radiographic findings may include:

  • increased soft tissue volume and/or density
  • soft tissue calcification or ossification
  • adjacent bone pressure atrophy/erosion

Differential Diagnosis:

  • gouty arthritis
  • multiple reticulohistiocytosis
  • soft tissue mass secondary to aggressive bone tumor

Here are some examples of soft tissue tumors followed by interpretations (*):

  • Case 1a
  • Case 1b
  • *Case 1a
  • *Case 1b
  • Case 2a
  • *Case 2b
  • Case 3
  • *Case 3
  • Case 4
  • *Case 4
  • Case 5
  • *Case 5
  • Case 6
  • *Case 6
lipoma DP
lipoma Lat
lipoma DP

DP view. Findings include a large, well defined fat-like density (L) in the soft tissues medial to the second toe proximal phalanx.

lipoma Lat

Lateral view. Findings include a large, well defined fat-like density (L) in the soft tissues superior to the second toe proximal phalanx. Based upon the DP and lateral view findings, this mass is located along the superomedial aspect of the second toe, which correlated clinically.

ossification Lat
ossification Lat

Lateral view. A large ossicle (O; contains trabeculations and a thin cortical margin) presents in the soft tissues inferior to the calcaneus and plantar fascia. Diagnosis: post-traumatic ossification.

xanthoma
xanthoma

Lateral view. A large, oval-shaped connective tissue-like density (X) is seen posterior to the talus and calcaneus, which appears to also involve the Achille's tendon. Diagnosis: xanthoma.

fibroma
fibroma

Lateral view. The arrow identifies a well defined, oval-shaped connective tissue density in the soft tissues inferior to the midfoot. There is no bony involvement nor calcification of the lesion. Diagnosis: fibroma.

ganglion
ganglion

Lateral view. A well defined, oval-shaped connective tissue-like density (G) is seen in the soft tissues superior to the midfoot. There is no bony involvement nor calcification of the lesion. Diagnosis: ganglion cyst.

synovial osteochondromatosis
synovial osteochondromatosis

Lateral view. Oval, calcific homogeneous densities (arrows) are seen anterior to the ankle joint. Increased soft issue density and volume (S) also is evident. Diagnosis: synovial osteochondromatosis.

Should a radiographic study be ordered for suspicion of a soft tissue tumor?

Definitely yes. Observed findings may expand or limit the differential diagnosis list, especially if there is the presence of calcification, ossification, or adjacent bone involvement (erosion or osteolysis).

What are the best views to order?

At a minimum order DP (AP if ankle) and lateral views. Oblique views can be valuable adjunct views if the lesion is clinically located:

  • superomedial, inferomedial, superolateral, or inferolateral on the foot, or
  • anteromedial, anterolateral, posteromedial, or posterolateral on the ankle.
How is this pathology radiographically similar (or different) to gouty arthritis or multiple reticulohistiocytosis?

Soft tissue massses may cause well-defined erosions similar to that seen in gouty arthritis and multiple reticulohistiocytosis.

Other information

Ultrasound and MRI may be valuable adjunct studies.

References:

  1. Resnick, D: Bone and Joint Imaging, 2nd edition, WB Saunders, 1996.
  2. Christman RA: Foot and Ankle Radiology, 2nd edition, Lippincott Williams & Wilkins, 2015.