Adipocyte-rich CTNNB1-mutated Intramuscular Gardner Fibroma Progressing to Desmoid Fibromatosis

Herein, we report a unique case of an 11-year-old boy who presented with a rapidly growing soft-tissue mass after biopsy of a stable fat-rich lesion present in the calf muscles since infancy, with Magnetic resonance imaging findings suggesting an intramuscular adipocytic tumor. The resection showed gardner fibroma (GF) and desmoid fibromatosis (DF). DF arising from a preexisting GF (the so-called “GF-DF sequence”) is a well-documented phenomenon. Although immunohistochemistry was negative for nuclear beta-catenin expression, a CTTNB1 S45F mutation, which has been associated with aggressive behavior in DF, was identified in both components using a next-generation sequencing-based molecular assay. This is the first time a mutation in CTNNB1 has been identified in GF and the GF-DF sequence, thus expanding our knowledge of the molecular pathogenesis of the GF-DF sequence and highlighting the role of molecular testing in pediatric soft-tissue tumors.

More than 5 years ago, The Desmoid Tumor Working Group started a consensus initiative in Europe with the aim of harmonizing the strategy among clinicians and setting up treatment recommendations for patients with desmoid tumors (DTs). This review summarizes the latest joint, global, evidence-based guideline approach to DT management. Moreover, a number of gray areas in the treatment recommendations are discussed, and possible future perspectives on the treatment armamentarium for patients with DTs are presented.

The aim of this study was to evaluate the efficacy and safety of treatment of desmoid tumours (DT) with single agent oral vinorelbine. A retrospective review of patients treated with vinorelbine 90mg orally on Days 1, 8 and 15 of a 28-day cycle from January 2004-July 2019 was performed. Response was assessed using Response Evaluation Criteria in Solid Tumours version 1.1. 29 patients were included. Response rate was 20.7% (6/29) and clinical benefit rate (response by RECIST 1.1 and/or clinical symptom improvement) was 65.5% (19/29). No patient experienced grade 3 or above toxicity. Common toxicities were grade 1-2 nausea (14/26, 48.3%), fatigue (9/26, 31.0%) and diarrhea (4/26, 13.8%). Single agent oral vinorelbine is an effective, safe and well tolerated treatment for DT.

The purpose of this report is to quantify mandibular growth in a young patient undergoing partial hemi-mandibular reconstruction with a free fibula flap (FFF) utilizing advanced three-dimensional software. A 2-year old underwent left hemi-mandibular reconstruction with a FFF following resection of a desmoid tumor. The condyle was preserved. Using 3D software, changes in mandibular growth and morphology were evaluated based on preoperative (2.1 years old) and postoperative (2.5 years and 5.2 years old) computed tomography imaging. Mandibular growth occurred throughout the mandible in both postoperative evaluations. Providing an objective evaluation using 3D software, we have demonstrated growth throughout the reconstructed mandible, with greatest growth occurring at the preserved condyle. Despite scientific limitations of our study, the potential for mandibular growth appears to remain after FFF reconstruction, offering successful functional and cosmetic outcomes.

A 53-year-old man was referred to our institution with an abdominal mass that was found incidentally on ultrasonography for prostate cancer screening. Multidetector computed tomography (MDCT) showed a cystic and solid mass with fat components in the ileal mesentery, measuring 25 cm in size. The mass was insinuating into the ileal vessels, invading the mesenteric side of jejunal loops, closely abutting the third portion of the duo-denum and uncinate procsess of the pancreas. The differential diagnosis included infiltrating liposarcoma, gastrointestinal stromal tumor (GIST), desmoid tumor (DT) and malignant peripheral nerve sheath tumor (MPNST) with entrapment of the mesneteric fat. Based on the imaging findings, surgical treatment of the en block resection of the mass was planned. A mesenteric mass excision with partial pancreatectomy, duodenectomy and small bowel segmental resection was performed. The mass encompassed duodenum, first jejunum loops and their mesentery. The resected specimen consisted of a large firm and white mesenteric mass, 24 × 11 cm, attached to the duodenum, small intestine and the uncinate process of the pancreas.

Benign soft tissue lesions are 300 times as common as soft tissue sarcomas; hence, the likelihood of confusion is high. Lesions that are larger than 5?cm, deep, show infiltrative growth, or recur despite benign histology are suspicious for soft tissue sarcoma. The biopsy incision must be carefully chosen; in large lipomas, atypical lipomatous tumor should be considered in the differential diagnosis. Lymphomas can be misdiagnosed and treated as undifferentiated soft tissue sarcoma. Vascular tumors and epithelioid lesions require more attention in histopathologic diagnostics and staging. Inflammatory lesions and aggressive fibromatosis (desmoid tumor) should also be borne in mind. In general, staging should be adapted to the underlying tumor biology. Neoadjuvant and adjuvant multimodal therapy must be discussed with the patient and used in a targeted manner. Superficial infiltrating sarcomas are prone to intralesional resection and may require intraoperative frozen section histology. If plastic reconstruction is necessary, a two-step procedure after proven tumor-free margins can be beneficial. Cavities and seromas, tight sutures, and closing the wound with clips are particularly critical. Wound drains at the thigh, pelvis, and groin should be left longer. Early revision in cases of hematoma or critical wound healing have proven beneficial. Adjuvant therapies are best planned before discharge from hospital. Overall, tumor-specific follow-up can significantly reduce the disadvantages of a recurrence resection.