Clinicopathological features of 70 desmoid-type fibromatoses confirmed by beta-catenin immunohistochemical staining and CTNNB1 mutation analysis

We reviewed 85 cases of desmoid-type fibromatosis (DF) and performed Sanger sequencing for detecting mutations in CTNNB1 and immunostaining for detecting beta-catenin localization. We included 70 DF samples, of which 56 cases demonstrated nuclear beta-catenin localization and 43 cases harboured CTNNB1 mutations. CTNNB1-mutant DF samples consistently displayed nuclear beta-catenin expression and were derived from larger-sized tumours compared to samples with wild-type CTNNB1. When we further classified DF cases into 2 subgroups based on the type of specimen, excised specimens with nuclear beta-catenin expression frequently displayed CTNNB1 mutation and no statistical correlation between nuclear beta-catenin expression and CTNNB1 mutation was observed in biopsies. When we classified CTNNB1 mutation cases into 2 subgroups (DF with T41A or T41I, and DF with S45F or S45P), T41A or T41I mutations were observed more frequently in males than in females. Additionally, DF tumours harbouring S45F or S45P mutations were located more frequently in the abdominal wall than tumours with T41A or T41I mutations. In conclusion, CTNNB1 mutation correlates with nuclear beta-catenin expression in larger or excised DF tumours, and DF harbouring CTNNB1 mutations manifest variable clinical presentations.

To investigate the efficiency of pre-therapy magnetic resonance imaging (MRI) features in predicting the prognosis of desmoid-type fibromatosis patients treated with imatinib. A total of 38 desmoid-type fibromatosis patients treated with imatinib were collected in this retrospective study. The high signal intensity on pre-therapy MRI was evaluated on axial T2 and T1 contrast-enhanced sequences with fat suppression. Hyperintense T1 contrast enhancement (CE) proportion (? 75%) was identified as an independent predictor for PFS. Patients with hyperintense T1 CE proportion <75% demonstrated no progression, while patients with hyperintense T1 CE proportion ?75% demonstrated a progression rate of 78.4%. Hyperintense T1 CE proportion in the tumor is a potential predictor of disease progression in patients with desmoid-type fibromatosis treated with imatinib. Hyperintense T1 CE proportion <75% indicates progression-free during treatment.

Desmoid-type fibromatosis (DF) is a locally aggressive but non-metastatic (myo)fibroblastic neoplasm. A hallmark of the tumor is nuclear positivity for beta-catenin in immunohistochemistry due mostly to CTNNB1 mutations. However, a recent study has reported that even beta-catenin ‘nuclear-negative’ DFs can harbor CTNNB1 mutations and that the positive ratio of nuclear beta-catenin in DF is different among antibodies. Here, we reviewed soft tissue lesions for which the possibility of DF was considered and compared the sensitivity and specificity of nuclear beta-catenin for the diagnosis of DF among commonly used anti-beta-catenin antibodies, i.e., clone beta-catenin 1, 17C2 and 14. We analyzed 26 cases of DF, 28 cases of benign fibroblastic lesions, and 27 cases of other soft tissue tumors. The sensitivity and specificity of nuclear beta-catenin for the diagnosis of DF were different among antibodies; 54% and 98% in clone beta-catenin 1, 85% and 84% in 17C2, and 96% and 62% in 14. IHC of LEF1 showed comparable results with IHC of beta-catenin, with a sensitivity of 88% and specificity of 76%. Additionally, when beta-catenin 1 was used, DFs showed characteristic dotted cytoplasmic staining, often appearing as rings. Our results might be helpful for making a correct diagnosis of DF.

A 70-year-old man was admitted to our hospital with acute abdominal pain. Abdominal CT showed a 6-cm-sized tumor near the third portion of the duodenum, and a duodenal GIST was suspected. Although the abdominal pain was intense and the tumor was suspected to be ruptured, the vital signs were stable; therefore, we initially planned to perform an elective surgery. However, because the pain could not be controlled, the surgery was performed on the 6th day of hospitalization. Pathological findings showed that the resected specimen was a desmoid tumor and the surgical margins were negative. The postoperative course 1 year after surgery was favorable, and no tumor recurrence occurred.

Desmoid tumours are rare, locally aggressive neoplasms exhibiting high tendency for recurrence, even after complete resection. Only 1 in 5 of them originates from the chest wall, usually measuring less than 10 cm at diagnosis. Herein, we report the case of a woman presenting with symptoms of gradual lung compression by a giant desmoid tumour occupying the entire hemithorax. She underwent complete surgical resection of the tumour and chest wall reconstruction. She had disease recurrence 15 months later and currently remains under regular follow-up. The management of intrathoracic desmoid tumours is challenging because they are usually not diagnosed until they become large enough to cause compression symptoms. While medical management is the primary modality of treatment, surgery could be considered in selected cases where significant symptoms arise, and the functional status is impaired secondary to the tumour. Adjuvant radiotherapy to minimise the risk of local recurrence should also be considered.

We report two patients with extremity desmoid tumor who were each found at MRI to have an unsuspected pseudoaneurysm within their tumor after prior treatments (surgery and systemic therapy in one, surgery alone in the other). Such a pseudoaneurysm probably results from weakening of an arterial wall by adjacent desmoid tumor, as well as from local trauma. Due to the potential risk for life-threatening rupture of a pseudoaneurysm, one patient underwent surgical repair and the other, coil embolization. To our knowledge the presence of pseudoaneurysm has been reported within a few cases of abdominal desmoid tumor but not within an extremity desmoid tumor. This diagnosis has not been reported to have been made at MRI, either.