Home » What is SARCOMA? » Soft Tissue Sarcoma Reference Guide » Desmoid and Other Fibrous Tumors
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Alternative diagnostic termsDesmoid FibromatosisAggressive Fibromatosis
Common anatomical locationsExtremities = 30-40% of cases, abdominal wall = 20%, retroperitoneum/abdominal cavity = 15%, and chest wall = 10-15%.
Pathology commentLocally aggressive, but non-metastasizing deep-seated myo-fibroblastic neoplasm with infiltrative growth and a very high incidence of local recurrence.
Familial adenomatous polyposis (FAP) is a hereditary condition associated with mutations in the APC gene and leading to a predisposition for developing Desmoid tumors in addition to the development of numerous colonic polyps and a risk of colorectal cancer. Desmoid tumors (DTs) are a significant extraintestinal manifestation of FAP that occurs in approximately 10%-30% of individuals with this condition (see Desmoid FAP reference below).
SourceHornick JL, Fritchie KJ, van de Rijn M, Crago AM. Desmoid fibromatosis. In: WHO Classification of Tumors Editorial Board. Soft tissue and bone tumors [Internet]. Lyon (France): International Agency for Research on Cancer; 2020 [2024 Dec 29]. (WHO Classification of Tumors Series, 5th ed.; vol. 3). Available from: https://tumourclassification.iarc.who.int/login?redirecturl=%2Fchapters%2F33
Desmoid Tumors in Familial Adenomatous Polyposis (FAP):
Yen T, Stanich PP, Axell L, et al. APC-Associated Polyposis Conditions. 1998 Dec 18 [Updated 2022 May 12]. In: Adam MP, Feldman J, Mirzaa GM, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2024. Available from: https://www.ncbi.nlm.nih.gov/books/NBK1345/
Maria Laura De Marchis, Francesco Tonelli, Davide Quaresmini, Domenica Lovero, David Della-Morte, Franco Silvestris, Fiorella Guadagni, Raffaele Palimirotta. Anticancer Research Jul 2017, 37 (7) 3357-3366; available from: Reference for Desmoid FAP Syndrome: https://ar.iiarjournals.org/content/37/7/3357.long
For diagnosis or treatmentAny center listed as a SARC Honor Roll member in the Sarcoma Centers Directory »
Patient advocacyAny organization with an established program for patient triage, support, and education. See Patient Support Organizations »
Diagnostic-specific organizations:Desmoid Tumor Research Foundation (USA)Desmóide Brasil | Associação Brasileira do Tumor Desmóide (Brazil)SOS Desmoide (France)Desmoid Foundation (France)SOS Desmoid (Germany)Desmoid Foundation (Italy)
Clinical trialsSARC Clinical Trials – NoneFind other clinical studies registered on ClinicalTrials.gov
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Alternative diagnostic termsCollagenous Fibroma
Common anatomical locationsUpper arm, shoulder, lower limb, back, forearm, hand, and foot.
Pathology commentAbundant collagenous or myxocollagenous matrix; low vascularity; scattered, bland, stellate-shaped, and spindled fibroblastic cells. Benign tumors with a significant risk of recurrence but do not usually metastasize.
SourceHornick JL, Miettinen M, Bridge JA. Desmoplastic Fibroblastoma. In: WHO Classification of Tumors Editorial Board. Soft tissue and bone tumors [Internet]. Lyon (France): International Agency for Research on Cancer; 2020 [2024 Dec 29]. (WHO Classification of Tumors Series, 5th ed.; vol. 3). Available from: https://tumourclassification.iarc.who.int/login?redirecturl=%2Fchapters%2F33
For diagnosis or treatmentAny center listed in the Sarcoma Centers Directory »
Alternative diagnostic termsNone
Common anatomical locationsDeep soft tissues of the extremities, trunk, head, and neck.
Pathology commentDiagnosis of exclusion
SourceHornick JL, Yoshida A, Folpe AL. Adult fibrosarcoma. In: WHO Classification of Tumors Editorial Board. Soft tissue and bone tumors [Internet]. Lyon (France): International Agency for Research on Cancer; 2020 [2024 Dec 29]. (WHO Classification of Tumors Series, 5th ed.; vol. 3). Available from: https://tumourclassification.iarc.who.int/welcome/
Alternative diagnostic termsIntra-abdominal Desmoplastic Round Cell Tumor(Also see Highly Aggressive Soft Tissue Tumors of Uncertain Differentiation)
Common anatomical locationsExtremities in two-thirds of cases and more common in the lower rather than upper extremities
Pathology commentNo areas of atypical lipomatous tumor, well-differentiated liposarcoma, or other lines of differentiation present.
SourceFolpe AL, Pedeutour F, Montgomery EA. Pleomorphic liposarcoma. In: WHO Classification of Tumors Editorial Board. Soft tissue and bone tumors [Internet]. Lyon (France): International Agency for Research on Cancer; 2020 [2024 Dec 29]. (WHO Classification of Tumors series, 5th ed.; vol. 3). Available from: https://tumourclassification.iarc.who.int/login?redirecturl=%2Fchapters%2F33
Common anatomical locationsThese neoplasms occur most commonly in the trunk, head and neck, proximal extremities, or shoulder girdle and pelvis.
Pathology commentDFSP has a storiform architecture and uniform spindle cell morphology; diffusely infiltrative growth with a honeycomb pattern in the subcutis; expression of CD34; fibrosarcomatous DFSP: fascicular architecture with increased mitotic activity.
SourceHornick JL, Mentzel TDW, Pedeutour F. DermatofibroSarcoma protuberans. In: WHO Classification of Tumors Editorial Board. Soft tissue and bone tumors [Internet]. Lyon (France): International Agency for Research on Cancer; 2020 [2025 Jan 1]. (WHO Classification of Tumors Series, 5th ed.; vol. 3). Available from: https://tumourclassification.iarc.who.int/welcome/
Alternative diagnostic termsSolitary Fibrous Tumor (SFT)
Common anatomical locationsIMT shows a wide anatomical distribution, most frequently arising in the abdominal soft tissues (mesentery, omentum, retroperitoneum) and pelvis, followed by the lung, mediastinum, head and neck, gastrointestinal tract, and genitourinary tract (including the bladder and uterus).
Pathology commentIMT has loose or compact fascicles of spindle cells with a prominent inflammatory infiltrate and a variable fibrous or myxoid stroma; expression of ALK (seen in as many as 60% of cases).
SourceHornick JL, Yamamoto H. Inflammatory myofibroblastic tumor. In: WHO Classification of Tumors Editorial Board. Soft tissue and bone tumors [Internet]. Lyon (France): International Agency for Research on Cancer; 2020 [2025 Jan 1]. (WHO Classification of Tumors Series, 5th ed.; vol. 3). Available from: https://tumourclassification.iarc.who.int/welcome/
Alternative diagnostic termsMyofibrosarcoma
Common anatomical locationsLow-grade myofibroblastic sarcoma shows a wide anatomical distribution in the extremities, the head and neck region, and especially the tongue and oral cavity.
Pathology commentLow-grade myofibroblastic sarcomas are characterized by diffusely infiltrative growth between skeletal muscle fibers; contain cellular fascicles of spindle cells with pale eosinophilic cytoplasm; usually demonstrate moderate, focal nuclear atypia and variable expression of SMA (smooth muscle antigen) and/or desmin.
SourceHornick JL, Mentzel TDW. Low-grade myofibroblastic Sarcoma. In: WHO Classification of Tumors Editorial Board. Soft tissue and bone tumors [Internet]. Lyon (France): International Agency for Research on Cancer; 2020 [2025 Jan 1]. (WHO Classification of Tumors Series, 5th ed.; vol. 3). Available from: https://tumourclassification.iarc.who.int/welcome/
Alternative diagnostic termsPRDM10-Rearranged Soft Tissue Tumor
Common anatomical locationsThis tumor most frequently occurs in the thigh/lower extremities, followed by the arm, buttock, and shoulder.
Pathology commentCharacterized by a fascicular or sheet-like proliferation of spindled cells with abundant, eosinophilic, granular to glassy cytoplasm, marked nuclear pleomorphism, a low mitotic count, diffuse CD34 expression, and frequent aberrant keratin immunoreactivity.
SourceHornick JL, Rekhi B, Folpe AL, Yu L. Superficial CD34-positive fibroblastic tumor. In: WHO Classification of Tumors Editorial Board. Soft tissue and bone tumors [Internet]. Lyon (France): International Agency for Research on Cancer; 2020 [2025 Jan 1]. (WHO Classification of Tumors Series, 5th ed.; vol. 3). Available from https://tumourclassification.iarc.who.int/welcome/
Common anatomical locationsHands and other acral dorsal extremities.
Pathology commentCharacterized by pleomorphic fibroblastic cells with macro-nucleoli in a myxohyaline background with prominent inflammatory cell infiltrate.
SourceHornick JL, Montgomery EA, Antonescu CR, Folpe AL. Myxoinflammatory Fibroblastic Sarcoma. In: WHO Classification of Tumors Editorial Board. Soft tissue and bone tumors [Internet]. Lyon (France): International Agency for Research on Cancer; 2020 [2024 Dec 29]. (WHO Classification of Tumors Series, 5th ed.; vol. 3). Available from: https://tumourclassification.iarc.who.int/welcome/
Alternative diagnostic termsCongenital FibrosarcomaCellular Congenital Mesoblastic Nephroma
Common anatomical locationsSuperficial and deep soft tissues of the extremities.
Pathology commentCharacterized by an ETV6-NTRK3 fusion.
SourceHornick JL, Davis JL, Antonescu CR, Bahrami A. Infantile fibroSarcoma. In: WHO Classification of Tumors Editorial Board. Soft tissue and bone tumors [Internet]. Lyon (France): International Agency for Research on Cancer; 2020 [2024 Dec 29]. (WHO Classification of Tumors Series, 5th ed.; vol. 3). Available from: https://tumourclassification.iarc.who.int/welcome/
Common anatomical locationsExtremities pelvis and shoulder, more commonly in the lower extremities.
Pathology commentComprises a spectrum of malignant fibroblastic neoplasms with variably myxoid stroma, pleomorphism, and a distinctive curvilinear vascular pattern. Prior historical diagnosis included MFH.
SourceHornick JL, Huang HY, Mentzel TDW, Shibata T. Myxofibrosarcoma. In: WHO Classification of Tumors Editorial Board. Soft tissue and bone tumors [Internet]. Lyon (France): International Agency for Research on Cancer; 2020 [2024 Dec 29]. (WHO Classification of Tumors Series, 5th ed.; vol. 3). Available from: https://tumourclassification.iarc.who.int/login?redirecturl=%2Fchapters%2F33.
Common anatomical locationsProximal extremities and the trunk, usually sub-fascial in depth.
Pathology commentConsistently have either a FUS-CREB3L2 or FUS-CREB3L1 gene fusion.
SourceHornick JL, Doyle LA, Mertens F. Low-grade Fibromyxoid Sarcoma. In: WHO Classification of Tumors Editorial Board. Soft tissue and bone tumors [Internet]. Lyon (France): International Agency for Research on Cancer; 2020 [2024 Dec 29]. (WHO Classification of Tumors Series, 5th ed.; vol. 3). Available from: https://tumourclassification.iarc.who.int/login?redirecturl=%2Fchapters%2F33.
Common anatomical locationsUpper or lower extremities, pelvis, shoulder, and girdle.
Pathology commentA subset of sclerosing epithelioid fibrosarcomas are related morphologically and molecularly to low-grade fibromyxoid sarcoma.
SourceHornick JL, Doyle LA, Mertens F. Sclerosing epithelioid fibrosarcoma. In: WHO Classification of Tumors Editorial Board. Soft tissue and bone tumors [Internet]. Lyon (France): International Agency for Research on Cancer; 2020 [2024 Dec 29]. (WHO Classification of Tumors Series, 5th ed.; vol. 3). Available from: https://tumourclassification.iarc.who.int/login?redirecturl=%2Fchapters%2F33.
Alternative diagnostic termsTumor-like “Pseudotumor” conditions
Common anatomical locationsNone
Pathology commentNote the plethora of benign alternative diagnoses: Nodular fasciitis, Proliferative fasciitis and proliferative myositis; Myositis ossificans and fibro-osseous pseudotumors of the digits; Ischaemic fasciitis, Elastofibroma (typically involving the scapula); Fibrous hamartoma of infancy; Fibromatosis colli; Congenital Fibromatosis; Juvenile hyaline fibromatosis; “Inclusion body” fibromatosis; Fibroma of tendon sheath; Myofibroblastoma; Calcifying; aponeurotic fibroma, EWSR1-SMAD3-positive fibroblastic tumor (emerging); Angiomyofibroblastoma; Cellular angiofibroma; Angiofibroma of soft tissue; Nuchal-type fibroma; Acral fibromyxoma; Gardner fibroma; Lipofibromatosis; and Giant cell fibroblastoma.
SourcePending