Desmoid tumors Flashcards

1
Q

What are desmoid tumors (DT)?

A

DTs are rare, benign, slow-growing fibroblastic neoplasms that arise from musculoaponeurotic stromal elements, and tend to recur locally.

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2
Q

What is another commonly used name for DT?

A

DT is also known as aggressive fibromatosis; musculoaponeurotic fibromatosis; or desmoid-like fibromatosis (previously called fibrosarcoma grade I of desmoids type).

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3
Q

DT appears histologically similar to what tumors?

A

DT appears histologically similar to well-differentiated fibrosarcoma.

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4
Q

Any histopathologic features to differentiate DT from these tumors?

A

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)

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5
Q

What is the approximate incidence of DT?

A

2.4–4.3 cases/million population; this risk increases 1,000-fold in pts with FAP.

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6
Q

What genetic abnormality is associated with DT?

A

5%–15% of DTs are associated with mutations to the APC gene, resulting in FAP.

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7
Q

What is the clinical syndrome associated with DT?

A

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)

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8
Q

What genetic mutation presents in DT sporadic cases?

A

Activating Wnt/a-catenin (CTNNB1) pathway, identified in appx 85% of cases of sporadic DT.

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9
Q

Is there a sex or age predilection for DT?

A

Yes, DTs typically present in women during childbearing yrs. There is no racial or ethnic predilection.

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10
Q

What 2 environmental conditions are associated with DT?

A

DTs have been associated with high estrogen states (such as pregnancy) and trauma per retrospective and anecdotal reports

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11
Q

What is the typical presentation of an extremity DT?

A

Most DTs of the extremity present as a deep-seated, painless mass with a Hx of slow growth.

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12
Q

What % of DTs are intra-abdominal, and with what clinical syndrome are intra-abdominal DTs associated?

A

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.

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13
Q

What is the typical presentation of an intra-abdominal DT?

A

An intra-abdominal DT can present with bowel ischemia, obstruction, or complications with ileoanal anastomosis after colectomy for FAP.

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14
Q

What is the natural Hx of untreated DTs?

A

DTs can regress spontaneously or remain stable, however, ∼50% will continue to grow slowly and invade into surrounding structures.

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15
Q

Do DTs have metastatic potential?

A

No. DTs do not have metastatic potential but are locally aggressive with a predilection for LR.

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16
Q

After a careful H&P, what imaging should be done to evaluate for a DT?

A

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.

17
Q

How do DTs display on MRI imaging?

A

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

18
Q

What is the metastatic workup for DTs?

A

DTs are benign and do not have metastatic potential. Consequently, no systemic imaging is needed outside of the primary tumor.

19
Q

Can DT be distinguished from malignant ST tumors on the basis of imaging?

A

No. DT cannot be distinguished from malignant ST tumors on the basis of imaging

20
Q

Define the staging system for DT.

A

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

21
Q

What type of Bx should be done to evaluate a mass suspected of being a DT?

A

A core needle or open incisional Bx is the preferred method for any tumor that may be a malignant STS.

22
Q

What is considered the primary modality for Tx of DT?

A

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.

23
Q

What are the indications for Sg in pts with DT?

A

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.

24
Q

For what type of pts is nonoperative initial management of DT always entertained?

A

For pts with DTs that are large, slow-growing, involve the mesentery; encase vessels or joints or when anesthesia or Sg carries morbidity

25
Q

What is the recurrence rate after margin– Sg vs. margin+ Sg for primary DT?

A

In primary DT Tx with Sg, LR is 15% for –margin resection, and LR is 33% for +margin resection. (Janssen et al., BJS 2017)

26
Q

What is the recurrence rate after Sg (with +ve/indeterminate margin) for primary DT with or without adj RT?

A

In DT Tx with Sg (+ve/indeterminate margin), LR is 23% after RT, and LR is 40% without RT. (Janssen et al., BJS 2017)

27
Q

What factors should be considered when determining whether or not to offer adj RT for DT?

A

Factors to be considered when considering adj RT for DT:
1. Margin status. Margin– pts are unlikely to benefit.
2. Location. Adj RT for resected retroperitoneal/intra-abdominal DTs is
associated with significant Tx risks.
3. Salvage options. Lesions that may undergo repeat resections may be
appropriately observed.
4. Pt age. There should be a high threshold for using adj RT in children.

28
Q

What is the response rate (complete or partial) for inoperable DT treated with RT alone?

A

For inoperable DT treated with RT alone 50% showed complete or partial response. (EORTC 62991-22998, Ann Oncol 2013)

29
Q

What dose of RT is needed to control DT with RT alone?

A

A dose >50 Gy is needed to treat DT with RT alone. The recommended dose for gross Dz is 56 Gy.

30
Q

What dose of RT is recommended after an R1 resection of DT in a pt who cannot be salvaged with repeat resection?

A

A pt treated with adj RT after an R1 resection should be treated to a dose of 50 Gy in 1.8–2 Gy/fx.

31
Q

Define the CTV for RT in the management of DT.

A

The CTV to include when treating DT with RT includes the tumor bed (and/or gross tumor), a portion of the muscle compartment to cover fascial planes, or neurovascular structures along which tumor may track with a 3–5 cm CTV margin longitudinally and 2 cm in all other directions respecting bony, facial and compartmental boundaries.

32
Q

What are potential medical approaches to treat DT?

A

ER modulators (tamoxifen), NSAIDs, low-dose cytotoxic chemo (Mtx, vinblastine or doxorubicin based), interferon, TKI.

33
Q

What are recent projections for the trajectory of systemic medical Tx in DT?

A

Lev et al. from MDACC, showed a significant increase in systemic medical Tx in recent yrs with decreased reliance on Sg alone and suggested neoadj
Tx may be associated with improved outcomes.
De Camargo et al. (Cancer 2010) observed greatest radiological response with antiestrogens and anthracycline regimens than other agents

34
Q

What are the potential late complications associated with RT Tx to the extremity?

A

Late complications associated with RT to the extremities:

  1. Fibrosis
  2. Edema
  3. Fracture
  4. 2nd malignancy
  5. Joint stiffness
  6. Neuropathy
35
Q

How did IMRT affect RT complications?

A

IMRT and IGRT resulted in decrease of RT side effects. Reports on extremity sarcoma treated with IMRT from MSKCC and PMH showed edema 7.9%, 11.1% and stiffness 14.5%, 5.6% respectively.