Malignant Tumours of the Foot

 

Introduction

  • Very rare
  • 5% of musculoskeletal tumours are foot and ankle
    • Soft tissue tumours account for 25-52%
    • Bone tumours account for 48-52%
    • Malignant neoplasms account for 13-39%
  • Bone:
    • Chondrosarcoma – most common
    • Osteosarcoma, Ewing’s, fibrosarcoma, metastatic
  • Soft tissue:
    • Synovial sarcoma, myxofibrosarcoma, malignant melanoma
  • Even anatomical distribution
  • Often delay in diagnosis compared to other anatomical sites

 

Investigations

Key history:

  • Skin changes / ulceration
  • Peripheral nerve compression symptoms

Key examination:

  • Tinel’s sign
  • Skin pigmentation changes
  • Lateral and dorsal easier to diagnose than medial and plantar
  • Local lymph nodes
  • Pulsatility
  • Tethered to underlying structures

Increased suspicion of malignancy:

  • subfascial location
  • lump size > 5 cm
  • increase in size
  • pain and /or recurrence

Radiographs

  • Orthogonal    

USS

  • Good for soft tissue
  • Defines planes
  • Doppler for hypervascularity

MRI

  • Whole foot
  • If tibia/fibula – request whole bone to knee

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Figure 1. MRI of synovial sarcoma

CT

  • Local – whole foot
  • Staging – chest/abdo/pelvis

Nuclear Medicine

  • SPECT / PET CT

 

Management

  • Early referral to local tumour / sarcoma unit
  • Biopsy principles
    • Only after discussion with the local tumour service / MDT discussion
    • Fine needle aspiration for:
      • Cytology
      • Fluorescence in situ hybridization (FISH)
      • PCR
  • Core needle biopsy – tissue cylinder
  • Open incisional
    • Tumour capsule
    • Cortical margin in bony tumours

Biopsy rules

  • Should be same team that will perform the definite tumour resection
  • Minimally invasive: access the tumour through the least possible normal tissue / compartments; avoid contact with neurovascular structures
  • In line with definitive incision for later tumour resection and as far distally as possible
  • Should produce sufficient and representative sample of the lesion (no necrotic or liquid components, verification by immediate frozen sections)
  • Haemostasis should be performed meticulously to prevent cell spread
  • If a drain is used, it must be close to – and in line with – the main incision
  • Dedicated histopathologist

 

Management principles

  • Life vs limb salvage
  • MDT management
  • Most malignant tumours will require a wide local excision to ensure appropriate margins
  • Radical excision may mean amputation, especially in the midfoot / hindfoot; seek early input from psychological support / limb-fitting centre
  • Forefoot may be amenable to ray amputation
  • Know your foot amputations – ray / transmetatarsal / Lisfranc / Syme / BKA
  • Work with plastic surgeons to assess soft tissue options
  • Involve oncology for primary tumour management in metastatic disease
  • Chemotherapy / radiotherapy

           

Key malignant tumours

Synovial sarcoma

  • young to middle aged
  • intralesional calcifications in soft tissue mass
  • radical surgical excision with wide margins
  • 5-year survival ~55%

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Figure 2. Synovial sarcoma (images from different cases)

Malignant melanoma

  • most frequent malignant origin tumour
  • commonly sole of foot
  • wide excision with soft tissue coverage
  • very low 5 to 10-year survival

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Figure 3. Radiograph of malignant melanoma

Chondrosarcoma

  • age: 40s – 50s
  • most common malignant primary bone tumour
  • hindfoot > forefoot
  • irregular osseous lesion on plain radiographs
  • if intermediate or high-grade, consider amputation

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Figure 4. Chondrosarcoma

 

References

Rammelt S, Fritzsche H, Hofbauer C, Schaser KD. Malignant tumours of the foot and ankle. Foot Ankle Surg. 2020 Jun;26(4):363-370. doi: 10.1016/j.fas.2019.05.005. Epub 2019 May 11. PMID: 31126797

Hughes P, Miranda R, Doyle AJ. MRI imaging of soft tissue tumours of the foot and ankle. Insights Imaging. 2019 Jun 3;10(1):60. doi: 10.1186/s13244-019-0749-z. PMID: 31161474; PMCID: PMC6546775

Toepfer A, Harrasser N, Recker M, Lenze U, Pohlig F, Gerdesmeyer L, von Eisenhart-Rothe R. Distribution patterns of foot and ankle tumors: a university tumor institute experience. BMC Cancer. 2018 Jul 13;18(1):735. doi: 10.1186/s12885-018-4648-3. PMID: 30001718; PMCID: PMC6043962

Toepfer A. (2017). Tumors of the foot and ankle – A review of the principles of diagnostics and treatment. Fuß & Sprunggelenk. 15. 10.1016/j.fuspru.2017.03.004

Khan Z, Hussain S, Carter SR. Tumours of the foot and ankle. Foot (Edinb). 2015 Sep;25(3):164-72. doi: 10.1016/j.foot.2015.06.001. Epub 2015 Jun 10. PMID: 26233943