Desmoid tumors Flashcards
(35 cards)
What are desmoid tumors (DT)?
DTs are rare, benign, slow-growing fibroblastic neoplasms that arise from musculoaponeurotic stromal elements, and tend to recur locally.
What is another commonly used name for DT?
DT is also known as aggressive fibromatosis; musculoaponeurotic fibromatosis; or desmoid-like fibromatosis (previously called fibrosarcoma grade I of desmoids type).
DT appears histologically similar to what tumors?
DT appears histologically similar to well-differentiated fibrosarcoma.
Any histopathologic features to differentiate DT from these tumors?
Most neoplasms resembling DT have specific histologic diagnostic features and lack nuclear β-catenin immunoreactivity. 70%–75% of DTs express
nuclear a-catenin. (WHO 4th edition, 2013)
What is the approximate incidence of DT?
2.4–4.3 cases/million population; this risk increases 1,000-fold in pts with FAP.
What genetic abnormality is associated with DT?
5%–15% of DTs are associated with mutations to the APC gene, resulting in FAP.
What is the clinical syndrome associated with DT?
Gardner syndrome is associated with DT, and 10%–20% of pts with this syndrome will develop DT.
Sebaceous cysts, Osteomas, and Desmoid tumors.
(Mnemonic: Gardner SOD)
What genetic mutation presents in DT sporadic cases?
Activating Wnt/a-catenin (CTNNB1) pathway, identified in appx 85% of cases of sporadic DT.
Is there a sex or age predilection for DT?
Yes, DTs typically present in women during childbearing yrs. There is no racial or ethnic predilection.
What 2 environmental conditions are associated with DT?
DTs have been associated with high estrogen states (such as pregnancy) and trauma per retrospective and anecdotal reports
What is the typical presentation of an extremity DT?
Most DTs of the extremity present as a deep-seated, painless mass with a Hx of slow growth.
What % of DTs are intra-abdominal, and with what clinical syndrome are intra-abdominal DTs associated?
10%–30% of DTs are intra-abdominal, and they are associated with Gardner syndrome. Intra-abdominal DTs are often a source of significant morbidity and mortality.
What is the typical presentation of an intra-abdominal DT?
An intra-abdominal DT can present with bowel ischemia, obstruction, or complications with ileoanal anastomosis after colectomy for FAP.
What is the natural Hx of untreated DTs?
DTs can regress spontaneously or remain stable, however, ∼50% will continue to grow slowly and invade into surrounding structures.
Do DTs have metastatic potential?
No. DTs do not have metastatic potential but are locally aggressive with a predilection for LR.
After a careful H&P, what imaging should be done to evaluate for a DT?
An MRI of the extremity is recommended to evaluate the extent of an extremity DT. A CT or MRI of the abdomen may be helpful to evaluate an intra-abdominal or abdominal wall mass.
How do DTs display on MRI imaging?
On T1, DTs are near homogeneous and isointense to muscle; on T2 they are more heterogeneous. After initial growth, spontaneous evolution of desmoids is characterized by shrinking and an increase in low-signal areas on T2
What is the metastatic workup for DTs?
DTs are benign and do not have metastatic potential. Consequently, no systemic imaging is needed outside of the primary tumor.
Can DT be distinguished from malignant ST tumors on the basis of imaging?
No. DT cannot be distinguished from malignant ST tumors on the basis of imaging
Define the staging system for DT.
DTs are NOT included in AJCC 8th edition. There is no defined staging system for DT. Important features to guide the management include location, size, and the ability to resect with a wide margin
What type of Bx should be done to evaluate a mass suspected of being a DT?
A core needle or open incisional Bx is the preferred method for any tumor that may be a malignant STS.
What is considered the primary modality for Tx of DT?
Surgical resection used to be the gold standard. However, based on recent data describing a high rate of PFS (50%) and spontaneous regression (28%) a “watch and wait” policy is a reasonable option.
What are the indications for Sg in pts with DT?
Features to identify pts at low risk of progression, whom would most benefit from a “watch and wait” policy, have not yet been established. Sg is still a valuable option when the expected morbidity is low (function-preserving
Sg) with wide (2 cm) –SMs.
For what type of pts is nonoperative initial management of DT always entertained?
For pts with DTs that are large, slow-growing, involve the mesentery; encase vessels or joints or when anesthesia or Sg carries morbidity
