Diagnosis

Guidelines recommendations

Collaborating with specialists may improve prognoses and patients’ quality of life1,2

DTWG Guidelines†*

“Referral to experienced multidisciplinary teams is recommended at the time of initial diagnosis, for optimal advice on safety of an initial observation strategy.3“

“Management of desmoid tumours is complex and
should be carried out exclusively in designated desmoid tumour referral centers equipped with a multidisciplinary tumor board.*4“

†The DTWG includes more than 50 sarcoma experts from different disciplines, as well as patients, and patient advocates from Europe, North America, and Japan.3
*To update the 2020 global evidence-based consensus guideline on the management of patients with desmoid tumour, the Desmoid Tumour Working Group convened a meeting on 2023, reaching a consensus on the key aspects of the management of patients with DT.4
ESMO Soft Tissue and Visceral Sarcomas: ESMO-EURACAN-GENTURIS Clinical Practice Guidelines

“Pathological diagnosis should be made by a sarcoma expert pathologist.5”

NCCN Guidelines

“Prior to the initiation of the treatment plan, all patients should be evaluated and treated by a multidisciplinary team with expertise and experience in desmoid tumors.6”

Differential diagnosis

Achieving timely and accurate diagnosis remains a challenge7

Misdiagnosis is common in rare diseases such as desmoid tumours.7

  • 30–40% of desmoid tumour cases were reported to be misdiagnosed following histologic analysis7
  • The differential diagnosis is broad and includes both benign and malignant fibroblastic/myofibroblastic proliferations including:8
    • Hypertrophic scars
    • Keloids and nodular fasciitis
    • Low‐grade fibromyxoid sarcoma
    • Low‐grade myofibroblastic sarcoma
  • Nerve sheath tumours such as schwannoma, neurofibroma, perineurioma, and smooth muscle tumours such as leiomyomas, can also enter the differential diagnosis8
  • Low‐grade fibromyxoid sarcoma represents the most challenging differential diagnosis as it may exhibit significant morphologic overlap with desmoid tumours8
  • Another important differential diagnosis relating to intra‐abdominal desmoid tumours is gastrointestinal stromal tumour (GIST), as some cases of desmoid tumours may weakly and focally express KIT 8

Accurate diagnosis remains crucial to plan treatment appropriately.8

Diagnostic strategies

Diagnosis requires medical history review and physical examination, imaging and biopsy, as well as histopathology evaluation7

Diagnosis of desmoid tumours should be confirmed by an expert soft tissue pathologist.8
Imaging

Ultrasound may be used as first-line imaging, but if there is any suspicion for soft tissue sarcoma (STS) it should be followed by computed tomography (CT) or magnetic resonance imaging (MRI).5

In primary soft tissue tumours, MRI is the main imaging modality in the extremities, pelvis, and trunk.5

Standard radiographs may be useful to rule out a bone tumour, to detect bone erosion with a risk of fracture, and to show calcifications.5

CT can rule out a myositis ossificans in calcified lesions, and it has a role in pleuropulmonary sarcomas and retroperitoneal sarcomas (RPSs) where the performance is identical to MRI.5

High-risk features should prompt verification by biopsy:9

  • Recent increase in size
  • Deep location relative to the fascia
  • Size >4 cm
  • Invasive growth patterns seen on imaging
Core Needle Biopsy and Nuclear β-Catenin Staining

Following appropriate imaging assessment, the standard approach to diagnosis consists of multiple core needle biopsies, possibly by using ≥14-16 G needles.5

An excisional biopsy may be the most practical option for <3 cm superficial lesions. An open biopsy may be another option in selected cases, when decided within reference centres.5

A biopsy may underestimate the tumour malignancy grade. Therefore, when preoperative treatment is an option, radiological imaging [including [18F]2-fluoro-2-deoxy-D-glucose positron emission tomography/CT (FDG-PET/CT)] may be useful, in addition to pathology, to provide information that helps to estimate the malignancy grade.5

Histopathologic assessment and immunostaining for β-catenin are important for diagnosis of desmoid tumours.10

The DTWG Guideline identifies nuclear positivity for β-catenin as the key immunophenotypic feature of desmoid tumours.8

The presence of nuclear immunopositivity for β-catenin has been reported in 80% to 98% of sporadic desmoid tumour cases and in 60% to 70% of familial adenomatous polyposis (FAP)-associated desmoid tumour cases.8
Genetic Testing

CTNNB1 mutations and APC mutations are mutually exclusive in desmoid tumours, thus, detection of a somatic CTNNB1 mutation can help to exclude a syndromic condition. Conversely, CTNNB1 wild-type status in desmoid tumours, especially in an intra-abdominal tumour, should raise suspicion for FAP and necessitate more extensive diagnostic clinical work-up (e.g., colonoscopy or germline testing).8

Therefore, the DTWG Consensus Guideline recommends performing a mutational analysis in desmoid tumour biopsy specimens to confirm diagnosis and guide work-up when appropriate.8

  • 85% to 90% of desmoid tumours are sporadic and most often associated with activating mutations of the β-catenin gene CTNNB111
  • 10% to 15% of desmoid tumours are syndromic in the context of FAP and associated with germline inactivating mutations in APC11
Learn more about desmoid tumour management

APC, Adenomatous Polyposis Coli gene; CT, Computed Tomography; CTNNB1, Catenin β1 gene; FAP, Familial Adenomatous Polyposis; DTWG, Desmoid Tumor Working Group; ESMO, European Society for Medical Oncology; FDG-PET/CT, 18F-2-Fluoro-2-Deoxy-D-Glucose Positron Emission Tomography/ CT; GIST, GastroIntestinal Stromal Tumour; KIT, proto-oncogene, receptor tyrosine kinase oncogene; MRI, Magnetic Resonance Imaging; NCCN, National Comprehensive Cancer Network; RPS, RetroPeritoneal Sarcoma; STS, Soft Tissue Sarcoma.

  1. Husson O et al. Desmoid fibromatosis through the patients’ eyes: time to change the focus and organisation of care? Support Care Cancer. 2019;27(3):965-980.
  2. Joglekar SB et al. Current perspectives on desmoid tumors: the Mayo Clinic approach. Cancers (Basel). 2011;3(3):3143-3155.
  3. Gronchi A et al. Desmoid Tumor Working Group. The management of desmoid tumours: a joint global consensus-based guideline approach for adult and paediatric patients. Eur J Cancer. 2020;127:96-107.
  4. Kasper B et al. Desmoid Tumor Working Group. Current management of desmoid tumors: a review. JAMA Oncol. 2024; 10(8):1121-1128.
  5. Gronchi A et al. ESMO Guidelines Committee, EURACAN and GENTURIS. Soft tissue and visceral sarcomas: ESMO-EURACAN-GENTURIS Clinical Practice Guidelines for diagnosis, treatment and follow-up. Ann Oncol. 2021;32(11):1348-1365.
  6. Referenced with permission from the NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines®) for Soft Tissue Sarcoma V.1.2024. © National Comprehensive Cancer Network, Inc. 2024. All rights reserved. Accessed April 29, 2024. To view the most recent and complete version of the guideline, go online to NCCN.org. NCCN makes no warranties of any kind whatsoever regarding their content, use or application and disclaims any responsibility for their application or use in any way.
  7. Bektas M et al. Desmoid tumors: a comprehensive review. Adv Ther. 2023;40(9):3697-3722.
  8. Kasper B et al. Desmoid tumor working group. Current management of desmoid tumors: a review. [supplementary appendix] JAMA Oncol. 2024;10(8):1121-1128.
  9. Smolle MA et al. Diagnosis and treatment of soft-tissue sarcomas of the extremities and trunk. EFORT Open Rev. 2017;2(10):421-431.
  10. Carlson JW et al. Immunohistochemistry for β-catenin in the differential diagnosis of spindle cell lesions: analysis of a series and review of the literature. Histopathology. 2007;51(4):509-514.
  11. Penel N et al. Adult desmoid tumors: biology, management and ongoing trials. Curr Opin Oncol. 2017;29(4):268-274.