Large Intra-Abdominal Desmoid Tumor in a Deployed Soldier Initially Presented With Chronic Diarrhea

We report the case of a young, healthy soldier with chronic diarrhea and progressively worsening abdominal distention that began during his deployment to Honduras who was subsequently found to have a large intra-abdominal desmoid tumor. Desmoid tumor is a rare and benign neoplasm that typically appears on the extremity, abdominal wall, intra-abdominal space, and occasionally in the chest wall. This tumor may be associated with abdominal distension and gastrointestinal complaints. A large tumor can compress organs, causing local tissue damage and, in rare cases, death.

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.

The aim of this study is to evaluate the prevalence, determinants and prognostic value of pain at diagnosis in patients with desmoid-type fibromatosis (DF). We selected patients from the ALTITUDES cohort (NCT02867033), managed by surgery, active surveillance or systemic treatments, with pain assessment at diagnosis. Patients were invited to fill QLQ-C30 questionnaire and Hospital Anxiety Depression Scale. Determinants were identified using logistic models. Prognostic value on event-free survival (EFS) was evaluated using the Cox model. Overall, 382 patients were included in the current study (median age: 40.2 years; 117 men). The prevalence of pain was 36%, without significant difference according to first-line treatment (P = .18). In the multivariate analysis, pain was significantly associated with tumor size >50 mm (P = .013) and tumor site (P < .001); pain was more frequent in the neck and shoulder locations (odds ratio: 3.05 [1.27-7.29]). Pain at baseline was significantly associated with poor quality of life (P < .001), depression (P = .02), lower performance status (P = .03) and functional impairment (P = .001); we also observed a nonsignificant association with anxiety (P = .10). In the univariate analysis, baseline pain was associated with poor EFS; the 3-year EFS was 54% in patients with pain compared to 72% in those without pain. After adjustment for sex, age, size and line of treatment, pain was still associated with poor EFS (hazard ratio: 1.82 [1.23-2.68], P = .003). One third of recently diagnosed patients with DF experienced pain, especially those with larger tumors and neck/shoulder locations. Pain was associated with unfavorable EFS after adjustment for the confounders.

Background: Desmoid tumors are rare, locally aggressive, highly recurrent soft-tissue tumors without approved treatments. Methods: We conducted a phase 3, international, double-blind, randomized, placebo-controlled trial of nirogacestat in adults with progressing desmoid tumors according to the Response Evaluation Criteria in Solid Tumors, version 1.1. Patients were assigned in a 1:1 ratio to receive the oral γ-secretase inhibitor nirogacestat (150 mg) or placebo twice daily. The primary end point was progression-free survival. Results: From May 2019 through August 2020, a total of 70 patients were assigned to receive nirogacestat and 72 to receive placebo. Nirogacestat had a significant progression-free survival benefit over placebo (hazard ratio for disease progression or death, 0.29; 95% confidence interval, 0.15 to 0.55; P<0.001); the likelihood of being event-free at 2 years was 76% with nirogacestat and 44% with placebo. Between-group differences in progression-free survival were consistent across prespecified subgroups. The percentage of patients who had an objective response was significantly higher with nirogacestat than with placebo (41% vs. 8%; P<0.001), with a median time to response of 5.6 months and 11.1 months, respectively; the percentage of patients with a complete response was 7% and 0%, respectively. Significant between-group differences in secondary patient-reported outcomes, including pain, symptom burden, physical or role functioning, and health-related quality of life, were observed (P≤0.01). Frequent adverse events with nirogacestat included diarrhea (in 84% of the patients), nausea (in 54%), fatigue (in 51%), hypophosphatemia (in 42%), and maculopapular rash (in 32%); 95% of adverse events were of grade 1 or 2. Among women of childbearing potential receiving nirogacestat, 27 of 36 (75%) had adverse events consistent with ovarian dysfunction, which resolved in 20 women (74%). Conclusions: Nirogacestat was associated with significant benefits with respect to progression-free survival, objective response, pain, symptom burden, physical functioning, role functioning, and health-related quality of life in adults with progressing desmoid tumors. Adverse events with nirogacestat were frequent but mostly low grade.

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Desmoid fibromatosis is a myofibroblastic neoplasm of intermediate biologic potential, which has a strong predilection for local recurrence but does not metastasize. Arranged in long, sweeping fascicles with infiltrative borders, desmoid fibromatosis typically consists of uniform, bland myofibroblastic spindle cells that harbor mutation of CTNNB1 (or less often APC). In this report, we present a remarkable case of desmoid fibromatosis associated with striking nuclear pleomorphism. We hypothesize that this striking pleomorphism is due to a germline TP53 mutation, a finding first suspected due to strong and diffuse p53 staining by immunohistochemistry and subsequently confirmed by molecular testing. The combination of the pleomorphism and TP53 mutation in desmoid fibromatosis represents a novel finding unreported in the literature.