Adventitious bursitis

Pseudotumoural
soft tissue lesions of the foot and ankle: a pictorial review. Adventitious bursitis. A 54-year-old patient with a painful swelling located plantar to the first metatarsophalangeal joint. Short-axis fat-suppressed T2-WI (a), T1-WI (b) and fat-suppressed contrast-enhanced T1-WI (c): fluid collection plantar-medial to the first metatarsal head (long arrow) of high SI on T2-WI, and low SI on T1-WI, corresponding to a fluid-filled cavity. There is marked rim enhancement (arrowheads)
insightsimaging.springeropen.com • CC-by-2.0
Adventitious
bursitis • Adventitial bursitis secondary to a distal femoral osteochondroma - Ganzer Fall bei Radiopaedia
AlAli A, Adventitial bursitis secondary to a distal femoral osteochondroma. Case study, Radiopaedia.org (Accessed on 05 Jan 2023) https://doi.org/10.53347/rID-97174 • CC by-nc-sa 3.0 (modified)
Radiopaedia • CC-by-nc-sa 3.0 • de

Adventitious or adventitial bursitis refers to inflammation associated with adventitious bursae.

Adventitious bursae are not permanent native bursae. They can develop in adulthood at sites where subcutaneous tissue becomes exposed to high pressure and friction.

Clinical presentation

When present in the foot, patients may present with metatarsalgia .

Pathology

These begin when pre-existing small fluid spaces coalesce in loose connective tissue. The walls then progressively become differentiated from the adjacent connective tissue and a well-defined fluid-filled cavity is formed, which is lined by synovium-like columnar cells. Unlike permanent bursae, they lack a mesothelial lining.

Location
  • foot and ankle region: typical site and usually adjacent to bony prominences
    • medial eminence of the first metatarsal head
    • towards the plantar aspect of the metatarsal heads
  • overlying amputation stumps

Radiographic features 

Ultrasound 

A region of superficial swelling with a fluid (anechoic) tract corresponding to friction sites in typical locations can be seen.

MRI

May demonstrate an ill-defined lesion located in the subcutaneous fat. Typical signal characteristics are that of fluid:

  • T1: low signal
  • T2:
    • high signal
    • may have intralesional string- or band-like low-signal structures