PSMA-Avid Desmoid Tumor of the Abdominal Wall on 18F-Piflufolastat PET/CT

Prostate-specific membrane antigen (PSMA) PET/CT is widely used in the evaluation of suspected metastasis for initial definitive therapy and suspected recurrence of prostate cancer. We outline a case report of a 62-year-old man with history of prostate cancer treated with surgery, salvage radiation, and hormonal therapy presenting with rising PSA levels. There was incidental detection of a PSMA-avid subcutaneous abdominal wall mass on PSMA PET/CT study, which was consistent with desmoid fibromatosis on an ultrasound-guided biopsy.

Purpose of review: This article discusses the evolving approaches to desmoid tumors management, shedding light on recent developments.

Recent findings: Active surveillance has become the primary approach for managing primary peripheral desmoid tumors. This strategy was initially based on evidence from retrospective studies. Roughly 50% of cases managed with active surveillance show spontaneous stabilization or regression. Recent prospective trials conducted in Italy, The Netherlands, and France (2022-2023) confirm the efficacy of active surveillance, revealing 3-year progression-free survival rates ranging from 53.4 to 58%. For the patients under active surveillance, decisions regarding treatment are based on significant tumor growth or progressive symptoms. Moreover, three contemporary randomized trials investigated medical treatments for progressive or recurrent desmoid tumors. Sorafenib, pazopanib, and nirogacestat demonstrated clinical activity, as evidenced by favorable progression-free survival and objective response rates.

Summary: Active surveillance has solidified its position as the primary management approach for desmoid tumors, validated by three robust prospective studies. Three recent randomized trials explored medical treatment for progressive or recurrent desmoid tumors, revealing promising clinical activities.

A 13-year-old girl with a painful left neck mass was referred to our institution due to suspicions of malignancy. The patient reported pain that accompanied her frequent neck spasms. Computed tomography revealed a large, soft-tissue mass in the left neck, deep to the sternocleidomastoid. The lesion anteriorly displaced the internal carotid artery and both displaced and crushed the internal left jugular vein. Uniquely, a three-dimensional virtual reality model combining magnetic resonance imaging and computed tomography data was used to determine the lesion’s resectability and visualize which structures would be encountered or require protection while ensuring total resection. During operation, we confirmed that the mass also laterally displaced the brachial plexus, cranial nerves X and XI, and spinal nerves C3-C5 (including the phrenic) of the cervical plexus. Postsurgical pathological analysis confirmed a diagnosis of desmoid tumor, also known as aggressive fibromatosis, whereas DNA sequencing revealed a CTNNB1 mutation, a somatic genetic marker found in approximately 90% of desmoid tumor cases. When possible, the most widely used method for the treatment of desmoid tumors has been gross resection. Chemotherapy, radiotherapy, and local excision are also used in the treatment of fibromatoses when complete resection is judged infeasible. In this case, a complete surgical resection with tumor-free surgical margins was performed. A standard cervical approach with a modified posterolateral incision site was implemented to avoid a conspicuous anterior neck scar. No flap, nerve repair, or reconstruction was warranted. At 1 year of postsurgical follow-up, the patient showed minimal scarring and no signs of recurrence.

At present, studies on the risk factors associated with AF recurrence were relatively scarce. Reports on the recurrence factors of abdominal wall aggressive fibromatosis (AWAF) were even rarer, and most of them were single-center studies. In this study, we attempted to investigate clinical data of 148 AWAF patients from 21 tertiary hospitals in China to analyze the risk factors of postoperative recurrence.

Background: Sorafenib and pazopanib, two tyrosine kinase inhibitors (TKI), are widely used in patients with progressive symptomatic desmoid tumors (DT). Limited real-word data is available on long-term outcomes of patients who progressed on, stopped, or continued TKIs.

Methods: Patients diagnosed with DTs and treated with sorafenib or pazopanib between 2011 and 2022 at 11 institutions were reviewed. Patient history, response to therapy and toxicity were recorded. Statistical analyses utilized Kaplan-Meier and log-rank tests.

Results: 142 patients with DT treated with sorafenib (n = 126, 88.7 %) or pazopanib (n = 16, 11.3 %) were analyzed. The median treatment duration was 10.8 months (range: 0.07- 73.9). The overall response rate and the disease control rate were 26.0 % and 95.1 %, respectively. The median tumor shrinkage was – 8.5 % (range -100.0 %- +72.5 %). Among responders, the median time to an objective response was 15.2 months (range: 1.1 to 33.1). The 1-year and 2-year progression-free survival rates were 82 % and 80 %. Dose reductions were necessary in 34 (23.9 %) patients. Grade 3 or higher adverse events were reported in 36 (25.4 %) patients. On the last follow-up, 55 (38.7 %) patients continued treatment. Treatment discontinuation (n = 85, 59.9 %) was mainly for toxicity (n = 35, 45.9 %) or radiological or clinical progression (n = 30, 35.3 %). For the entire cohort, 36 (25.4 %) patients required subsequent treatment. In the 32 responders, only 1 (3.1 %) patient required a subsequent treatment. In patients who discontinued TKI, 25 (44.6 %) with stable disease received subsequent treatment compared to 0 (0.0 %) of responders.

Conclusion: This retrospective study represents the largest cohort of DT patients treated with sorafenib or pazopanib to date. Discontinuation of treatment in responders is safe. The optimal treatment duration in patients with stable disease remains to be defined.

Aggressive fibromatosis is a relatively rare disease. We describe 68Ga-FAPI-04 PET/CT findings in a case of histologically proved mesenteric aggressive fibromatosis. 68Ga-FAPI-04 PET/CT revealed a mass in the mesentery with increased FAPI activity. This case indicates that FAPI PET may be useful for evaluation of aggressive fibromatosis.