Learning you have a desmoid tumor

desmoid tumor tendril

An early and accurate diagnosis is important

Perhaps you’ve had a strange pain that will not go away, a visible lump under your skin, or a growing discomfort after a pregnancy.1-3 These are among the many possibilities that could start the process of getting diagnosed with a desmoid tumor. A doctor could even find a desmoid tumor while looking at a completely unrelated issue.3,4

Because desmoid tumors are so rare and can appear differently from person to person, people do not always get properly diagnosed right away. In fact, desmoid tumors are misdiagnosed approximately 30% to 40% of the time.5 One of the most common misdiagnoses is lipoma.6 Or a desmoid tumor may be incorrectly identified as scar tissue or another type of tumor.6,7

That can mean serious delays for some people in getting the care they need. But don’t worry—there are several ways to help get a timely and accurate diagnosis.

Desmoid tumors
are misdiagnosed




of the time5

Let’s describe this disease as it actually is. Because it isn’t benign. It doesn’t metastasize. But it is life altering. It’s life-changing.

DeAnn, patient with a desmoid tumor

DeAnn on a medical exam table

There are several ways to help get a timely and accurate diagnosis

NCCN Guidelines for Patients® provides a roadmap to help patients understand their diagnosis and treatment options. According to the NCCN Guidelines for Patients, it is important that a biopsy be performed. Imaging of the primary site with a CT or MRI will be done as needed.8

Otherwise, an incorrect diagnosis can result in delayed or incorrect treatment. This may lead to unnecessary surgery and risk of complications. Your doctor may choose to perform additional tests as well. If you have questions about getting diagnosed, be sure to ask your care team.

Evaluation and Diagnosis

Medical history and physical exam

A CT scan, MRI,9 and/or ultrasound to see what’s happening in the body can help doctors understand where the tumor is.4,10 A radiologist will review the images and write a report. They will send this report to your doctor, who will review these results with you8

Biopsy, or a tissue sample, is needed to diagnose a desmoid tumor. A biopsy is recommended before starting treatment9,10

Additional tests that may be helpful:10

Beta catenin can play a key role in desmoid tumors…and be a clue to diagnosis 

Beta catenin is a protein found in cells throughout the body. One of the roles of beta catenin is  to help regulate “cell signaling.”11 Cell signaling can instruct cells in the body when to grow and divide. Abnormal cell signaling may lead to tumor development and growth.12 Medical experts have found that beta catenin often accumulates excessively in desmoid tumors cells, causing tumors to overgrow.11

Beta catenin staining can help a pathologist determine whether a tumor is a desmoid tumor when they look at it under the microscope. Based on medical studies, 60% to 98% of desmoid tumors show beta catenin staining under a microscope.10

Read as much as you can, get yourself informed as best as possible. You have to be your own advocate. 

Melony, patient with a desmoid tumor

Melony standing in a field

Lipoma is a common misdiagnosis for those with desmoid tumors6,* 

What are lipomas? 

Lipomas are abnormal, benign growths of fatty tissue. Like desmoid tumors, they can appear anywhere in the body.13,14

Lipomas are the most common type of soft tissue tumor.13 They occur far more frequently than desmoid tumors.13 

  • 50% of soft-tissue tumors are lipomas15
  • 3% of soft-tissue tumors are desmoid tumors14

The rarity of desmoid tumors compared to lipomas may be one reason that desmoid tumors could be misdiagnosed as lipomas.5 Of desmoid tumors that are misdiagnosed, 40% were initially thought to be lipomas.6,*

From market research conducted by SpringWorks Therapeutics.6

Desmoid tumors and their “tendril-like” growths may be difficult to see fully using imaging tests like MRI, CT scans, or ultrasound.16 This may be another reason that a desmoid tumor could be misdiagnosed as a lipoma or another tumor type.  Under a microscope, the cells of a lipoma look very different than the cells of a desmoid tumor.10,13 A biopsy of the tumor is only way to see these differences before surgery. Ask your doctor whether a biopsy is appropriate for you.

What are some important differences between lipomas and desmoid tumors? 

  • Age of patients affected: while desmoid tumors are diagnosed most frequently in younger adults (age 20-44), lipomas are more common in adults aged 40-6013,17
  • Considerations for surgery:  The infiltrative nature of desmoid tumors may make them challenging to remove surgically. Their “tendril-like” growths can extend into layers of tissue beyond the tumor itself.5 In contrast, lipomas are generally well-defined within a thin capsule of tissue.18 After surgery, lipomas generally do not recur (come back).13 However, desmoid tumors can come back after surgery. It is reported that desmoid tumors may come back 24% to 77% of the time.19,20 The risk of having desmoid tumors come back after surgery can be higher for younger patients and those with larger tumors. Tumor location is also important. Desmoid tumors in the extremities (arms, legs, hands feet), chest wall, and within the abdominal cavity have a higher risk of coming back after surgery21

Questions to ask your doctor if you’ve been diagnosed with lipoma…and before treatment 

  • What kinds of tests (imaging, biopsy, genetic testing) have been used to confirm the diagnosis? 
  • Are there any other possible diagnoses? 
  • (If your doctor is managing with a “wait and see” approach) – when and how should the lipoma be monitored? 
  • (If you are considering surgery) – what are the possible benefits and risks of surgery? Will the tumor be tested by a pathologist after surgery? 

If you have questions about the diagnosis or treatment, it may be worthwhile to consult with a sarcoma specialist. You can find a sarcoma center here.

Knowledge is power

This Discussion Guide will provide information to help guide your conversations with your medical team.

  1. Cancer.Net. Desmoid tumor: risk factors. Accessed April 16, 2022. https://www.cancer.net/cancer-types/desmoid-tumor/risk-factors.
  2. Husson O, Younger E, Dunlop A, 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.
  3. Hanna D, Magarakis M, Twaddell W, Alexander R, Kesmodel S. Rapid progression of a pregnancy-associated intra-abdominal desmoid tumor in post-partum period: A case report. International Journal of Surgery Case Reports. 2016 Oct;26.
  4. Cancer.Net. Desmoid tumor: diagnosis. Accessed April 15, 2022. https://www.cancer.net/cancer-types/desmoid-tumor/diagnosis.
  5. Kasper B, Baumgarten C, Garcia J, et al; Desmoid Working Group. An update on the management of sporadic desmoid-type fibromatosis: a European Consensus Initiative between Sarcoma PAtients EuroNet (SPAEN) and European Organization for Research and Treatment of Cancer (EORTC)/Soft Tissue and Bone Sarcoma Group (STBSG). Ann Oncol. 2017;28(10):2399-2408.
  6. Data on file. SpringWorks Therapeutics.
  7. Penel N, Coindre JM, Bonvalot S, et al. Management of desmoid tumors: a nationwide survey of labelled reference centre networks in France. Eur J Cancer. 2016;58:90-96.

  8. Referenced with permission from the NCCN Guidelines for Patients® for Soft Tissue Sarcoma, V.1.2020. © National Comprehensive Cancer Network, Inc. 2020. All rights reserved. Accessed August 4, 2022. 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.
  9. Referenced with permission from the NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines®) for Soft Tissue Sarcoma V.2.2022. © National Comprehensive Cancer Network, Inc. 2022. All rights reserved. Accessed May 23, 2022. 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.
  10. 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 [supplementary appendix]. Eur J Cancer. 2020;127:96-107.
  11. Penel N, Chibon F, Salas S. Adult desmoid tumors: biology, management and ongoing trials. Curr Opin Oncol. 2017;29(4):268-274.
  12. NIH. National Cancer Institute. NCI dictionary of cancer terms: desmoid tumor. Accessed April 16, 2022. https://www.cancer.gov/publications/dictionaries/cancer-terms/expand/D.
  13. Kolb L, Yarrarapu SNS, Ameer MA, et al. Lipoma. [Updated 2022 Jul 11]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-.  Available from: https://www.ncbi.nlm.nih.gov/books/NBK507906/.
  14. Constantinidou A, Scurr M, Judson I, Litchman C. Clinical presentation of desmoid tumors. In: Litchman C, ed. Desmoid Tumors. Springer; 2012:chap 2. Accessed May 1, 2022. https://www.researchgate.net/publication/226455135.
  15. Li M, Zhang L, Xu XJ, Shi Z, Zhao XM. CT and MRI features of tumors and tumor-like lesions in the abdominal wall. Quant Imaging Med Surg. 2019 Nov;9(11):1820-1839.
  16. Rosa F, Marinetti C, Piscopo F, et al. Multimodality imaging features of desmoid tumor: a head-to-toe spectrum. Insights into Imaging. 2020 Dec;11(1):1-3.
  17. van Broekhoven DLM, Grünhagen DJ, den Bakker MA, van Dalen T, Verhoef C. Time trends in the incidence and treatment of extra-abdominal and abdominal aggressive fibromatosis: a population-based study. Ann Surg Oncol. 2015;22(9):2817-2823.
  18. Charifa A, Azmat CE, Badri T. Lipoma Pathology. [Updated 2021 Dec 12]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-.  Available from: https://www.ncbi.nlm.nih.gov/books/NBK482343/.
  19. Easter DW, Halasz NA. Recent trends in the management of desmoid tumors. Summary of 19 cases and review of the literature. Ann Surg. 1989;210(6):765-769.
  20. Skubitz KM. Biology and treatment of aggressive fibromatosis or desmoid tumor. Mayo Clin Proc. 2017;92(6):947-964.
  21. Crago AM, Denton B, Salas S, et al. A prognostic nomogram for prediction of recurrence in desmoid fibromatosis. Ann Surg. 2013;258(2):347-353.