Analysis of β-catenin expression and exon 3 mutations in pediatric sporadic aggressive fibromatosis

Infantile Sinonasal Myxoma Is Clinically and Genetically Distinct From Other Myxomas of the Craniofacial Bones and From Desmoid Fibromatosis

Sinonasal myxomas are rare benign tumors of the maxillary bone and sinus. There is published evidence that sinonasal myxomas occurring in children up to 3 years of age ("infantile sinonasal myxomas") are clinically distinctive and harbor Wnt signaling pathway alterations. Here, we characterized 16 infantile sinonasal myxomas and compared them to 19 maxillary myxomas and 11 mandibular myxomas in older patients. Clinical follow-up was available for 21 patients (46%) overall (median: 2.6 y; range: 4 mo to 21 y), including 10 of 16 infantile sinonasal myxomas (62%). None of the 8 resected infantile sinonasal myxomas recurred, despite positive margins in 6 of them. One incompletely resected infantile sinonasal myxoma underwent partial regression without additional treatment. In contrast, 4 of the 11 other myxomas with follow-up recurred (36%), including one that recurred twice. Imaging studies demonstrated all infantile sinonasal myxomas to be expansile lesions arising from the anterior maxillary bone adjacent to the nasal aperture, with peripheral reactive bone formation. Histologically, infantile sinonasal myxomas showed short, intersecting fascicles of bland fibroblastic cells with prominent stromal vessels. Examples with collagenous stroma showed some morphologic overlap with desmoid fibromatosis, although none showed infiltrative growth into adjacent soft tissue. Immunohistochemistry demonstrated nuclear β-catenin expression in 14 of 15 infantile sinonasal myxomas (93%), in contrast to 4 of 26 other myxomas of craniofacial bones (15%). Smooth muscle actin was expressed in only 1 of 11 infantile sinonasal myxomas (9%). Next-generation sequencing was successfully performed on 10 infantile sinonasal myxomas and 7 other myxomas. Infantile sinonasal myxomas harbored CTNNB1 point mutations in 4 cases (D32Y, G34E, G34R, and I35S), and none harbored alterations to the phosphorylation sites T41 and S45 that are altered in 99% of CTNNB1 -mutant desmoid fibromatoses. Three tumors showed alterations consistent with biallelic APC inactivation. Three infantile sinonasal myxomas that showed strong nuclear β-catenin expression were negative for CTNNB1 and APC alterations. Sequencing was negative for CTNNB1 or APC alterations in all 7 myxomas of craniofacial bones in older patients. Four of these myxomas in older patients (57%) showed copy number alterations, and all lacked known driving alterations. These findings support the notion that infantile sinonasal myxomas are clinically and genetically distinctive, and we propose the use of the diagnostic term "infantile sinonasal myxoma" to distinguish this tumor type from other myxomas of the craniofacial bones. Infantile sinonasal myxoma should be distinguished from desmoid fibromatosis because of its unique clinical presentation, more indolent clinical behavior, different morphology, different immunohistochemical profile, and different genetics. Given its indolent behavior even when marginally excised, infantile sinonasal myxoma can be managed with conservative surgery.

Novel insights into biomarkers of progression in Desmoid tumor

Desmoid tumor (DT) is a rare neoplasm characterized by the proliferation of myofibroblastic cells that infiltrates and invades adjacent tissues. Due to its locally aggressive and recurrent nature, DT often causes local symptoms and can be challenging to manage clinically. Therefore, identifying biomarkers that can predict the progression of DT and guide treatment decisions is critical. This review summarizes several biomarkers that have been implicated in active surveillance (AS) and the prediction of postoperative recurrence and attempts to elucidate their underlying mechanisms. Some of these novel markers could provide prognostic value for clinicians, and ultimately help facilitate optimal and accurate therapeutic decisions for DT.

Clinical Prognostic Factors and Integrated Multi-Omics Studies Identify Potential Novel Therapeutic Targets for Pediatric Desmoid Tumor

BACKGROUND

Desmoid tumor (DT), also known as desmoid-type fibromatosis (DTF) or aggressive fibromatosis (AF) is a rare mesenchymal tumor affecting both children and adults. It is non-metastasis but infiltrative, growing with a high recurrence rate to even cause serious health problems. This study investigates the biology of desmoid tumors through integrated multi-omics studies.

METHODS

We systematically investigated the clinical data of 98 extra-abdominal cases in our pediatric institute and identified some critical clinical prognostic factors. Moreover, our integrated multi-omics studies (Whole Exome Sequencing, RNA sequencing, and untargeted metabolomics profiling) in the paired PDT tumor/matched normal tissues identified more novel mutations, and potential prognostic markers and therapeutic targets for PDTs.

RESULTS

The top mutation genes, such as CTNNB1 (p.T41A and p.S45F) and MUC4 (p.T3775T, p.S3450S, etc.), were observed with a mutation in more than 40% of PDT patients. We also identified a panel of genes that are classed as the FDA-approved drug targets or Wnt/β-catenin signaling pathway-related genes. The integrated analysis identified pathways and key genes/metabolites that may be important for developing potential treatment of PDTs. We also successfully established six primary PDT cell lines for future studies.

CONCLUSIONS

These studies may promote the development of novel drugs and therapeutic strategies for PDTs.

The Role of Pharmacotherapeutic Agents in Children with Desmoid Tumors

Desmoid tumors (DT) are rare fibroblastic, soft-tissue tumors that do not metastasize but can aggressively infiltrate tissues causing significant chronic discomfort and/or functional impairment. In the pediatric population, the incidence of DT is greatest during infancy and adolescence but can occur at any age. Dysregulated β-catenin, most commonly resulting from mutations in either CTNNB1 or germline APC (adenomatous polyposis coli) drives DT. Most cases are sporadic but some are associated with predisposition syndromes such as familial adenomatous polyposis (FAP). Historically, treatment has been surgery. However, the recurrence rate after surgery can be high. Various systemic cytotoxic chemotherapy regimens used in other soft-tissue sarcomas have been applied to DT with differing results. Given the chronic and rarely life-threatening nature of this disease and the potential short- and long-term toxicity of these regimens, especially in children, alternative non-cytotoxic interventions have been investigated. Molecularly targeted agents such as tyrosine kinase and gamma secretase inhibitors have shown activity against DT. Innovative local control therapies are being employed as alternatives to surgery and radiation. Periods of prolonged stability and spontaneous regression in the absence of therapy in some patients has prompted wider adoption of an upfront active surveillance approach in the appropriate setting. This review will briefly summarize the epidemiology, pathophysiology, and clinical presentation of DT in children, then focus on historical, current, and future pharmacotherapeutic management and finally, propose areas for future study.

Pediatric and Infantile Fibroblastic/Myofibroblastic Tumors in the Molecular Era

Pediatric fibroblastic/myofibroblastic tumors are rare but include a wide variety of benign to malignant tumors. Given their uncommon frequency, they may present as a diagnostic dilemma. This article is focused on using clinical and pathologic clues in conjunction with the increasingly relevant and available molecular techniques to classify, predict prognosis, and/or guide treatment in these tumors.

Prognostic significance of CTNNB1 mutation in recurrence of sporadic desmoid tumors

Aim: Desmoid tumor (DT) is a rare, locally aggressive benign neoplasm with a high recurrence rate. The majority of sporadic DTs are associated with mutations in CTNNB1, but whether CTNNB1 mutations are associated with the risk of DT recurrence remains unclear. The goal of this meta-analysis was to evaluate the association between CTNNB1 mutation and recurrence in surgically treated DT patients. Methods: PubMed, Embase and Cochrane library were systematically searched. The outcome of interest was the risk of recurrence. The number of patients with CTNNB1 mutation and the number of recurrences they developed were recorded and compared. The quality of these studies was assessed using the Newcastle-Ottawa Quality Assessment Scale. Odds ratios and variances were calculated and pooled. Results: A total of eight studies were identified including 637 patients. S45F-mutated DTs were more likely to recur compared with wild type, T41A and other mutated DTs. However, there were no statistically significant differences in the rate of recurrence between wild type and T41A mutation or other mutation. Conclusions: Among CTNNB1 mutations, the mutation S45F is a high-risk factor for recurrence of DT and may be a predictive marker for the recurrence of sporadic DT.

Novel pathogenic alterations in pediatric and adult desmoid-type fibromatosis - A systematic analysis of 204 cases

Desmoid-type fibromatosis (DTF, aggressive fibromatosis) is a non-metastasizing mesenchymal neoplasm of deep soft tissue with a tendency towards local recurrence. Genetic alterations affecting canonical Wnt/β-catenin signaling are reported in the majority of DTF. While most sporadic DTF harbor somatic mutations in CTNNB1, germline mutations in adenomatous polyposis coli (APC) are known to occur in hereditary DTF types (FAP, Gardner-Syndrome). Additional single nucleotide variants (SNVs) in AKT1 (E17K) and BRAF (V600E) were reported in pediatric DTF with potential clinical implications. We performed targeted next-generation sequencing (NGS) in a large cohort of 204 formalin-fixed DTF samples, comprising 22 pediatric cases (patients age ≤18 years). The mutational status was correlated with clinicopathological characteristics. Overall, deleterious CTNNB1 mutations were detected in 89% of DTF, most frequently affecting the serine/threonine phosphorylation sites T41 and S45 of β-catenin. While the T41A CTNNB1 mutation was significantly more often identified in the mesenterial localization, DTF originating from extra-intestinal sites more frequently harbored the S45P CTNNB1 alteration. Beyond common mutations in CTNNB1, additional SNVs were demonstrated in 7% of the DTF cohort and in 18% of the pediatric DTF subgroup. The mutational spectrum included deleterious mutations in AKT1 (G311S/D and T312I), ALK (R806H and G924S), AR (A159T), EGFR (P848L), ERBB2 (H174Y), IDH2 (H354Y), KIT (V559D), RET (T1038A), SDHA (R325M), and SDHD (R115W), as characterized by in silico prediction tools. In conclusion, our study indicates that DTF may harbor a broader mutational spectrum beyond CTNNB1 mutations, comprising targetable alterations including the herewith first reported imatinib-sensitive KIT V559D mutation in DTF.

Next-Generation Sequencing in the Diagnosis of Rare Pediatric Sinonasal Tumors

The diagnosis of desmoid fibromatosis or other spindle cell tumors in the sinonasal region is very rare in children and needs to be thoroughly confirmed with immunohistochemical and/or molecular tests. We report 2 patients with such rare tumors and describe the use of next-generation sequencing in their evaluation. A 3-year-old female had a 4.4-cm midline nasal cavity mass involving the bony septum and extending into the base of the skull bilaterally. The moderate cellular fibroblastic proliferation revealed areas of thick keloid-like collagen bands and other areas with myxoid edematous stroma. Deep targeted sequencing identified a novel G34V mutation in the CTNNB1 gene consistent with desmoid fibromatosis. An 11-month-old male infant presented with a right nasal mass that extended through the cribriform plate into the anterior cranial fossa and involved the right ethmoid sinus and adjacent right orbit. Histology revealed an infiltrative atypical fibrous proliferation with focal calcifications that was negative for CTNNB1 and GNAS mutations. A novel RET E511K variant was identified in the tumor and later was also found in the germline and hence rendered of unknown significance. Both cases highlight the utility of next-generation sequencing in the evaluation of pediatric sinonasal spindle cell tumors that may have overlapping pathologic features. Reporting of rare or novel variants in tumor-only sequencing should be cautiously evaluated in children and pairing with germline sequencing may be needed to avoid the pitfall of assigning uncommon variants.

Clinical prognostic factors for pediatric extra-abdominal desmoid tumor: analyses of 66 patients at a single institution

Background and purpose

Pediatric desmoid tumor (PDT) is rare and has a high local recurrence rate. The purpose of the present study was to analyze clinical risk factors of local recurrence in PDT patients.

Materials and methods

We reviewed clinical data of 66 PDT patients from 2004 to 2015. All patients underwent macroscopically complete resection, and some recurrent tumors were prescribed radiotherapy. Factors such as sex, age at presentation, location, and proximity to nerves or vasculature were analyzed. The local recurrence rate and recurrence-free survival were analyzed with these factors.

Results

All patients in the present study were children and had extra-abdominal tumors. The median follow-up time was 6.6 years. Thirty-six (55%) patients had local recurrence. Age, sex, tumor site, tumor size, and proximity to nerves/vasculature had a significant impact on prognosis in univariate analysis. Radiotherapy decreased the local recurrence rate. In multivariate analysis, younger age, tumor location in buttocks, larger tumor, and proximity to important nerves/vasculature were independent risk factors for poor prognosis.

Conclusions

Favorable therapeutic strategies could be selected according to the preoperative prognostic risk factors. Radiotherapy should be considered for local recurrence of PDT.

Molecular characterization of Wnt pathway and function of β-catenin overexpression in medulloblastoma cell lines

Medulloblastoma (MB) is the most common malignant childhood brain tumor. MB is currently classified into four molecular subgroups (Wnt, Shh, Group 3, and Group 4). The wingless (Wnt) pathway is responsible for embryonic development and is deregulated in MB. We analyzed the activation of the Wnt pathway in MB cell lines and its correlation with the Shh pathway, with emphasis on the importance of cellular characterization. Transient β-catenin transfection led to an increase in the β-catenin gene and protein expression in MB cell lines. Wnt pathway activation resulted in a reduced number of colonies in all cell lines studied and a significant increase in the G2/M cell cycle phase only in ONS-76 cells. Regarding the Shh pathway, transfection caused a reduced expression of the PTCH1 and SMO genes only in the UW473 cells. Further studies are needed to understand the mechanism underlying the molecular events associated with the effects of Wnt activation in MB.

Overexpression of MUC1 and Genomic Alterations in Its Network Associate with Prostate Cancer Progression

We investigate the association of MUC1 with castration-resistant prostate cancer (CRPC), bone metastasis, and PC recurrence. MUC1 expression was studied in patient-derived bone metastasis and CRPCs produced by prostate-specific PTEN^−/− mice and LNCaP xenografts. Elevations in MUC1 expression occur in CRPC. Among nine patients with hormone-naïve bone metastasis, eight express MUC1 in 61% to 100% of PC cells. Utilizing cBioPortal PC genomic data, we organized a training (n = 300), testing (n = 185), and validation (n = 194) cohort. Using the Cox model, a nine-gene signature was derived, including eight genes from a MUC1-related network (APC, CTNNB1/β-catenin, GALNT10, GRB2, LYN, SIGLEC1, SOS1, and ZAP70) and FAM84B. Genomic alterations in these genes reduce disease-free survival (DFS) in the training (P = .00161), testing (P = .00699), entire (training + testing, P = 5.557e-5), and a validation cohort (P = 3.326e-5). The signature independently predicts PC recurrence [hazard ratio (HR) = 1.731; 95% confidence interval (CI): 1.104-2.712; P = .0167] after adjusting for known clinical factors and stratifies patients with high risk of PC recurrence using the median (HR 2.072; 95% CI: 1.245-3.450, P = .0051) and quartile 3 (HR 3.707, 95% CI: 1.949-7.052, P = 6.51e-5) scores. Several novel β-catenin mutants are identified in PCs leading to a rapid onset of death and recurrence. Genomic alterations in APC and CTNNB1/β-catenin reduce DFS in two independent PC cohorts (n = 485, P = .0369; n = 84, P = .0437). The nine-gene signature also associates with reductions in overall survival (P = .0458) and DFS (P = .0163) in melanoma patients (n = 367). MUC1 upregulation is associated with CRPC and bone metastasis. A nine-gene signature derived from a MUC1 network predicts PC recurrence.

Genomic Alterations of Adamantinomatous and Papillary Craniopharyngioma

Craniopharyngiomas are rare histologically benign but clinically challenging neoplasms. To obtain further information on the molecular genetics and biology of craniopharyngiomas, we analyzed a cohort of 121 adamantinomatous and 16 papillary craniopharyngiomas (ACP, PCP). We extracted DNA from formalin-fixed paraffin-embedded tissue and determined mutational status of CTNNB1, BRAF, and DDX3X by Sanger sequencing, next generation panel sequencing, and pyrosequencing. Sixteen craniopharyngiomas were further analyzed by molecular inversion profiling (MIP); 76.1% of the ACP were mutated in exon 3 of CTNNB1 encoding for β-catenin and there was a trend towards a worse event-free survival in cases mutated at Thr41. Next generation panel sequencing of 26 ACP did not detect any recurrent mutations other than CTNNB1 mutations. BRAF V600E mutations were found in 94% of the PCP, but not in ACP. GISTIC analysis of MIP data showed no significant larger chromosomal aberrations but a fraction of ACP showed recurrent focal gains of chromosomal material, other cases showed loss in the chromosomal region Xq28, and a third group and the PCP had stable genomes. In conclusion, the crucial pathogenetic event appears to be WNT activation in ACP, whereas it appears to be activation of the Ras/Raf/MEK/ERK pathway by BRAF V600E mutations in PCP.

Biology and Treatment of Aggressive Fibromatosis or Desmoid Tumor

Aggressive fibromatosis, also known as desmoid-type fibromatosis (DTF) or desmoid tumor, is an uncommon locally invasive tumor. Because of its low incidence and variable behavior, DTF is often first seen by physicians who are not familiar with it, and recent advances in understanding this disease have led to changes in treatment approaches. The Wnt (β-catenin) pathway appears to play a key role in DTF pathogenesis, and recent studies of DTF biology suggest a possible model of DTF pathogenesis. Histologically, DTF shows a poorly circumscribed proliferation of myofibroblast-like cells with variable collagen deposition, similar to the proliferative phase of wound healing, and DTF has been associated with trauma and pregnancy. Desmoid-type fibromatosis may be a useful model of the tumor stroma in carcinomas as well as other fibrosing diseases such as progressive pulmonary fibrosis. The clinical course of DTF can vary greatly among patients, complicating the determination of the optimal treatment approach. Treatment options include surgery, nonsteroidal anti-inflammatory drugs with or without hormonal manipulation, chemotherapy, radiation therapy, and other forms of local therapy. Many treatments have been used, but these are not without toxicities. Because of the variable nature of the disease and the potential morbidity of treatment, some cases of DTF may do better without treatment; simple observation is often the best initial treatment. This review used a PubMed search from January 1, 1980, through October 31, 2016, using the terms fibromatosis and desmoid and discusses DTF disease characteristics, pathophysiology, and treatment options as well as examines several cases illustrating key points in the biology and treatment of this heterogeneous disease.

Long-term outcome of sporadic and FAP-associated desmoid tumors treated with high-dose selective estrogen receptor modulators and sulindac: a single-center long-term observational study in 134 patients

Aim of this study is to evaluate the outcome of long-term conservative treatment with sulindac and high-dose selective estrogen receptor modulators (SERMs) for sporadic and FAP-associated desmoid tumors. Desmoids are very rare tumors in the general population but occur frequently in FAP patients, being encountered in 23-38 %. Treatment of desmoids is still most controversial since response cannot be predicted and they are prone to develop recurrence. This study included all desmoid patients that were treated and followed at our institution and had completed at least 1 year of treatment. Response was defined as stable size or regression of desmoid size between two CT or MRI scans. A total of 134 patients were included. 64 (47.8 %) patients had a confirmed diagnosis of FAP, 69 (51.5 %) patients were sporadic. Overall 114 (85.1 %) patients showed regressive or stable desmoid size. Patients with previous history of multiple desmoid-related surgeries showed less-favorable response. The mean time to reach at least stable size was 14.9 (±9.1) months. After regression or stabilization, medication was tapered in 69 (60.5 %) of the treated patients with only one long-term recurrence after >10 years. The results of this study fortify the role of sulindac and high-dose SERMs as an effective and safe treatment for both, sporadic and FAP-associated desmoid tumors. While invasive treatment frequently results in high recurrence rates, high morbidity and high mortality, this conservative treatment is successful in most patients. The recurrence rate is negligible with no desmoid-related mortality in this large series. Therefore surgical resection, especially for mesenteric desmoids, should be deferred favoring this convincingly effective, well tolerated regimen.

Simple resection of truncal desmoid tumors: A case series

Desmoid tumors of the extra-abdominal and abdominal wall have been associated with morbidity due to the aggressive nature of the surgery and high recurrence rates. Surgery that does not cause functional impairment is desired for patients with desmoid tumors. In the present study, among patients with desmoid tumors who were prospectively and consecutively treated with identical conservative treatment with meloxicam, a selected patients of patients were treated with less invasive surgery than wide-resection. Out of 60 patients pathologically diagnosed with desmoid tumors, 9 patients with tumors refractory to conservative treatment and 4 patients who refused to receive this type of treatment were treated with planned simple resection. Subsequently, the clinical outcome of the patients and the mutational status of the catenin β-1 (CTNNB1) gene in the tumors were analyzed. The mean age of the 13 patients that underwent planned simple resection was 39 years, and the tumors were located in the abdominal wall in 6 cases, the chest wall in 4 cases and the neck in 3 cases. All excised specimens were evaluated and positive microscopic margins were identified; however, during the mean follow-up period of 30 months, 12/13 cases, 7 of which had T41A mutations and 5 of which had no mutations (wild-type), did not develop recurrence. Only 1 initial case with an S45F mutation in the CTNNB1 gene developed recurrence. The results of the present prospectively treated with simple resection and retrospectively analyzed study suggest that planned simple resection could serve as a therapeutic modality for extraperitoneal desmoid tumors, particularly truncal ones with a wild-type or T41A mutational status.

AKT1 and BRAF mutations in pediatric aggressive fibromatosis

Aside from the CTNNB1 and adenomatous polyposis coli (APC) mutations, the genetic profile of pediatric aggressive fibromatosis (AF) has remained poorly characterized. The aim of this study was to shed more light on the mutational spectrum of pediatric AF, comparing it with its adult counterpart, with a view to identifying biomarkers for use as prognostic factors or new potential therapeutic targets. CTNNB1,APC,AKT1,BRAF TP53, and RET Sanger sequencing and next‐generation sequencing (NGS) with the 50‐gene Ion AmpliSeq Cancer Hotspot Panel v2 were performed on formalin‐fixed samples from 28 pediatric and 33 adult AFs. The prognostic value of CTNNB1,AKT1, and BRAF mutations in pediatric AF patients was investigated. Recurrence‐free survival (RFS) curves were estimated with the Kaplan–Meier method and statistical comparisons were drawn using the log‐rank test. In addition to the CTNNB1 mutation (64%), pediatric AF showed AKT1 (31%), BRAF (19%), and TP53 (9%) mutations, whereas only the CTNNB1 mutation was found in adult AF. The polymorphism Q472H VEGFR was identified in both pediatric (56%) and adult (40%) AF. Our results indicate that the mutational spectrum of pediatric AF is more complex than that of adult AF, with multiple gene mutations involving not only CTNNB1 but also AKT1 and BRAF. This intriguing finding may have clinical implications and warrants further investigations.

Extra-abdominal desmoid fibromatosis: A review of management, current guidance and unanswered questions

Extra abdominal desmoid fibromatosis is a complex condition with many recognised treatments including active observation, hormonal therapy, chemotherapy, radiotherapy and surgical resection. There is large variation in the natural history of individual desmoid tumours, with some cases progressing aggressively and others regressing spontaneously when observed alone. This combined with an absence of accurate clinical predictors of a desmoid tumour's behaviour has led to difficulties in identifying which patients would benefit most from aggressive treatment, and which could be adequately managed with a policy of active observation alone. This review explores the aetiology and common presentation of extra-abdominal desmoid fibromatosis including the condition's histopathological, clinical and radiological characteristics. The current evidence for potential predictors of desmoid tumour behaviour is also reviewed, along with the indications and evidence for the multitude of treatments available. We also summarise the published guidelines that are currently available for oncologists and surgeons managing extra-abdominal desmoid fibromatosis, and highlight some of the unanswered questions that need to be addressed to optimise the management of this condition.

Prognostic value of CTNNB1 gene mutation in primary sporadic aggressive fibromatosis

BACKGROUND

Aggressive fibromatosis (AF) comprises tumors with a varying biological behavior. Genetic tumor characteristics may be predictive of recurrence; hence, the prognostic value of three specific mutations on the CTNNB1 gene was evaluated in relation to known clinicopathologic risk factors in patients with primary, sporadic AF.

METHODS

In a multi-institutional retrospective cohort study of patients with primary extra-abdominal and abdominal wall AF who underwent surgical treatment, the original pathology specimens were reviewed for the presence of a T41A, S45F, and 45P mutations on the CTNNB1 gene. For these mutations, the risk of recurrence was analyzed by the Kaplan-Meier method with log-rank test. Univariable and multivariable Cox regression was performed to calculate hazard ratios.

RESULTS

A total of 101 patients were analyzed. During a median follow-up of 41 months, 17 recurrences were detected; the cumulative 5-year recurrence rate was 22.8 %. A specific CTNNB1 mutation was found in 76 patients, with the majority of patients having a T41A mutation (n = 49). CTNNB1 mutations were associated with the risk of recurrence: the presence of a S45F mutation was associated with a 5-year cumulative risk of recurrence of 63.8 % (P < 0.001). Multivariable analysis showed that young age and S45F mutation were independent risk factors (P = 0.011 and P < 0.001).

CONCLUSIONS

The presence of specific CTNNB1 mutations was predictive for recurrence in patients after surgical treatment for primary, sporadic extra-abdominal and abdominal AF. A S45F mutation increased the risk of recurrence significantly.

Desmoplastic fibroma of the rib with cystic change: a case report and literature review

Desmoplastic fibroma (DF) is a rare, locally aggressive, solitary tumor microscopically composed of well-differentiated myofibroblasts with abundant dense collagen deposition. The most common sites are the long tubular bones and mandible. To our knowledge, only five cases of DF in the ribs have been reported. Here, we report a case of DF in this rare location with unusual radiological findings. A 40-year-old man presented with a 4-year history of swelling of the right chest wall. Radiographs revealed a mass at the right 9th rib, and computed tomography demonstrated a mass of 14 × 12 × 8 cm at the right 9th rib with expanded cystic change and marked calcification that appeared to have arisen from the bone. Open biopsy suggested DF. Total excision was performed, and the chest wall was reconstructed. The surgical specimen was a yellowish tumor with multilocular cystic change containing a viscous liquid. The tumor was composed of a proliferation of less-atypical spindle-shaped cells in a collagenous background. The cystic change was observed in the extra-osseous lesion. No β-catenin cytoplasmic/nuclear accumulation was detected, and no β-catenin or GNAS genetic mutations were detected. A final diagnosis of DF was made on the basis of the pathological and radiological findings. The patient was successfully treated with total excision of the tumor with no evidence of recurrence 6 months after surgery.

Arthropathy, osteolysis, keloids, relapsing conjunctival pannus and gingival overgrowth: a variant of polyfibromatosis?

Polyfibromatosis is a rare fibrosing condition characterized by fibromatosis in different body areas and by keloid formation, and which can be associated with arthropathy and osteolysis. Familial occurrence has been described, but the cause remains unknown. Here, we describe a patient with characteristics of polyfibromatosis with arthropathy who had in addition severe conjunctival fibrosis, distinctive face, gingival overgrowth, and pigmented keloids. We discuss the resemblances and differences with polyfibromatosis and descriptions of other, similar patients. We conclude that at present it remains uncertain whether the patient has a variant of polyfibromatosis or a separate entity.

CTNNB1 genotyping and APC screening in pediatric desmoid tumors: a proposed algorithm

Desmoid fibromatosis is a rare, locally aggressive fibroblastic/myofibroblastic tumor that occasionally involves children. We examined a series of pediatric desmoids for CTNNB1 mutations, seen in sporadic tumors, and APC germline mutations, associated with familial adenomatous polyposis (FAP). Forty-four desmoids in pediatric patients were identified in the pathology files of 2 large referral centers (1995-2009). Clinical charts were reviewed for history of FAP. Germline APC gene mutations were determined on blood samples from patients presenting with FAP. Immunohistochemistry for beta-catenin was performed. CTNNB1 genotyping was done by Sanger sequencing on formalin-fixed paraffin-embedded tissue. CTNNB1 mutations were observed in 29 of 44 (66%) desmoids, with 3 mutations identified: T41A (64%), S45F (29%), and S45P (7%). Germline APC mutations were present in 7 (16%) desmoid patients. Eight (18%) patients had desmoids that were wild type for CTNNB1 and had no known clinical signs or family history suspicious for FAP at the time of testing or with extended follow up (n  =  6). Beta-catenin nuclear labeling was observed in 38 of 41 (92%) tested cases, 34 (89%) of which showed mutations in either CTNNB1 (n  =  29) or APC (n  =  5). Nuclear localization of beta-catenin was seen in the majority of pediatric desmoids and was most often associated with somatic mutations in CTNNB1. However, a significant proportion of pediatric patients harbored germline mutations in APC. Given the implications, genetic counseling is recommended for children diagnosed with desmoid tumors lacking CTNNB1 mutations because this population is enriched for FAP patients.