Myofibroma with Atypical Features can Mimic Low-Grade Myofibroblastic Sarcoma: Two Paediatric Cases.

Myofibroma is a rare benign mesenchymal tumor that frequently affects the pediatric population with a predilection for the head and neck region. About 10% of myofibroma cases, presenting atypical features, can be misinterpreted as low-grade myofibroblastic sarcoma (LGMS), with therapeutic and prognostic impact. Here, we report two pediatric cases of benign myofibroblastic tumors, one of them showing typical characteristics of myofibroma, the other was an atypical myofibroma, which initially mimicked low-grade myofibroblastic sarcoma. Atypical myofibromas, despite its distinctive characteristics, follow a benign course, similar with typical myofibroma. It is necessary to distinguish atypical myofibroma from low-grade myofibroblastic sarcoma and avoid unnecessary invasive therapy.

Deep Convolutional Neural Network for Accurate Classification of Myofibroblastic Lesions on Patch-Based Images.

OBJECTIVE: This study aimed to implement and evaluate a Deep Convolutional Neural Network for classifying myofibroblastic lesions into benign and malignant categories based on patch-based images. METHODS: A Residual Neural Network (ResNet50) model, pre-trained with weights from ImageNet, was fine-tuned to classify a cohort of 20 patients (11 benign and 9 malignant cases). Following annotation of tumor regions, the whole-slide images (WSIs) were fragmented into smaller patches (224 × 224 pixels). These patches were non-randomly divided into training (308,843 patches), validation (43,268 patches), and test (42,061 patches) subsets, maintaining a 78:11:11 ratio. The CNN training was caried out for 75 epochs utilizing a batch size of 4, the Adam optimizer, and a learning rate of 0.00001. RESULTS: ResNet50 achieved an accuracy of 98.97%, precision of 99.91%, sensitivity of 97.98%, specificity of 99.91%, F1 score of 98.94%, and AUC of 0.99. CONCLUSIONS: The ResNet50 model developed exhibited high accuracy during training and robust generalization capabilities in unseen data, indicating nearly flawless performance in distinguishing between benign and malignant myofibroblastic tumors, despite the small sample size. The excellent performance of the AI model in separating such histologically similar classes could be attributed to its ability to identify hidden discriminative features, as well as to use a wide range of features and benefit from proper data preprocessing.

Large congenital myopericytoma of the lower eyelid.

Congenital fibrous soft tissue tumors in the eyelids are exceptionally rare, with only seven cases of neonatal myofibromas reported. Myopericytoma, a variant with pericytic differentiation, has not previously been described in neonatal eyelid tumors. This report details a case of a massive congenital myopericytoma in a newborn's lower eyelid. The lesion had a broad area of adhesion to the anterior lamella of the lid. After resection, when the child was 11 days old, the resulting defect was successfully reconstructed with a V-Y type perforator-based flap.

Isolated Radial Nerve Palsy in a Newborn Due to a Congenital Myofibroma: A Rare Case of Peripheral Nerve Injury.

Isolated musculoskeletal infantile myofibroma is a rare tumor of pediatric age. The majority of cases are seen in children under two years old, but it can occur at any age as a painless enlarging mass that involves bone, skin, or soft tissue, typically accompanied by compression symptoms. Perineural involvement is extremely rare in myofibromas. Neurological impairment can occur during infancy but isolated nerve palsy, particularly in peripheral nerves within the upper extremity, is very uncommon. Neonatal radial nerve palsy is a rare entity caused by different conditions. Among these, we mention local tumors affecting peripheral nerves, such as myofibroma. There are few cases described in the literature, which mainly concern adult patients. The authors present a case of congenital isolated radial nerve palsy in a newborn with MF of the right elbow, which resulted in impairment of the wrist and finger extension. Following a six-month monitoring period, the patient underwent surgical treatment to restore function to his right wrist and hand. This involved excising the infiltrated radial nerve segment associated with palliative surgery. Despite the benignity of this lesion, severe nerve damage and perineural involvement may require surgical treatment with nerve resection and reconstruction.

Solitary Myofibroma of the oral and maxillofacial regions in pediatric patients: A clinicopathological analysis of ten patients and review of 75 cases.

BACKGROUND: The imaging manifestations of oral and maxillofacial myofibroma/myofibromatosis can vary among patients. Although many clinical cases have been reported, a consensus on the clinicopathological features of and treatment principles for this disease is lacking. PURPOSE: This study aimed to summarize the clinicopathological features of solitary myofibroma of the oral and maxillofacial regions in pediatric patients. METHODS: The clinical data, histological features, and immunohistochemical characteristics of ten pediatric patients who underwent surgical removal and subsequent pathological diagnosis of myofibroma were collected and retrospectively and cross-sectionally analyzed. RESULTS: Seven patients were male, and 3 were female, with ages ranging from 3 months to 6 years (mean: 2.6 years). The patients presented with solitary lesions involving the mandibular gingiva and adjacent mandible (4 patients), mandible (2 patients), oral floor and submandibular area and adjacent mandible (1 patient), gingiva (1 patient), maxilla (1 patient), and oropharynx (1 patient). Light microscopy revealed spindle-shaped tumor cells organized in bundles or vortex patterns, forming a hemangiopericytoma-like perivascular pattern, whereas immunohistochemical staining revealed diffuse smooth muscle actin (SMA) positivity. All patients underwent surgical resection, and none experienced recurrence over the 12- to 82-month follow-up. CONCLUSIONS: Solitary myofibroma in the oral and maxillofacial regions is predominantly observed in infants and young children, with a higher incidence among males. The prognosis is favorable following localized lesion resection or curettage of jawbone lesions. Accurate recognition of the clinical, radiological, and pathological features of the disease will reduce the misdiagnosis rate.

Postauricular Myofibroma of the Facial Canal: A Case Report.

Myofibromatosis is a proliferative disorder characterized by the development of soft tissue neoplasms referred to as myofibromas that predominantly occur in infants and young children. These lesions have been described using varied terminologies since they were first reported in 1951. However, these neoplasms are histopathologically characterized by benign fibroblast and myofibroblast proliferation containing a biphasic presentation of spindle-shaped cells surrounding a central zone of less differentiated cells arranged in a hemangiopericytoma-like pattern in all cases. Usually, myofibromatosis occurs in children aged <2 years and is observed at birth in nearly 60% of cases. We report a rare case of myofibroma in an 8-year-old boy who presented with an approximately 6-month history of a left postauricular mass. Histopathological evaluation of the resected mass confirmed the diagnosis.

Intraosseous myofibroma mimicking an odontogenic lesion: case report, literature review, and differential diagnosis.

BACKGROUND: Intraosseous myofibroma of the jaw is a rare neoplasm of mesenchymal origin with limited comprehensive understanding. It typically affects patients in the first two decades of life with a male predilection. CASE PRESENTATION: This study presents a rare case of myofibroma mimicking an odontogenic lesion in a 2-year-old boy. The patient presented with an incidental finding of a painless swelling of the right mandibular ramus of unknown etiology. Imaging analysis revealed a solid, expansile lesion adjacent to the germinal zone of the right mandibular first molar. Histopathologic analysis and immunohistochemistry after incisional biopsy suggested a possible central odontogenic fibroma, and the patient underwent total enucleation, leading to the final diagnosis of intraosseous myofibroma. Follow-up examinations showed no evidence of recurrence. CONCLUSIONS: This report contributes to the understanding of myofibroma in pediatric patients and underscores the critical role of meticulous histopathologic examination for effective surgical planning and optimal patient outcomes.

Solitary Intraosseous Myofibroma of the Mandible in a Nine-Year-Old Child: A Case Report and Literature Review.

Myofibroma (MF) is a benign neoplasm derived from myofibroblasts. While they are infrequent, these tumors are predominantly found in the pediatric group and seldom manifest as intraosseous mandibular tumors. Herein, we present a 9-year-old female with a radiolucent lesion in the left mandible associated with malposed left lower canine and 1st premolar teeth. Clinical examination revealed a slightly tender 5×4 cm firm mass resulting in an expansion of the buccal and lingual aspects of the mandible in the canine and first premolar region. An incisional biopsy revealed a benign tumor consisting of spindle cells organized in fascicles, alongside dispersed thin-walled blood vessels. Tumor cells tested positive for α-smooth muscle actin (SMA) and vimentin. Given these findings, a diagnosis of MF was established. To the best of our knowledge, only 45 cases of solitary MF of the mandible have been reported in the pediatric age group in the literature. We describe one additional case and provide a review of the literature.

Myopericytoma/myofibroma as a stromal component of mixed epithelial and stromal tumor of the kidney: A case report.

Mixed epithelial and stromal tumors (MESTs) of the kidney are rare renal neoplasms, primarily affecting middle-aged women. These tumors are characterized by a mix of epithelial and stromal components. While generally benign, MESTs require accurate diagnosis and appropriate management due to the potential for malignant transformation. The present study reports the case of a 75-year-old male patient who underwent a partial nephrectomy following the incidental discovery of a kidney tumor. Histopathological examination revealed a partially cystic tumor with solid areas, measuring 26 mm in diameter. The tumor had cysts lined with cuboidal cells and an ovarian-like stroma. The solid component consisted of elongated cells with eosinophilic cytoplasm and oval nuclei, showing angiocentric growth around small blood vessels without nuclear atypia or mitoses. Since the morphology of the solid component could not reveal the differentiation of those cells, immunohistochemical staining was performed and a myopericytoma/myofibroma component was established, mostly based on the positivity of smooth muscle actin, muscle-specific actin, h-caldesmon, estrogen receptor, progesterone receptor, solute carrier family 2 facilitated glucose transporter member 1 and collagen IV, along with a lack of staining for desmin, CD34, CD31 and CD99. Thus, to the best of our knowledge, for the first time in the literature, MEST with myopericytoma/myofibroma stromal component in a male patient was reported.

Clinicopathological features of myofibromas and myofibromatosis affecting the oral and maxillofacial region: A systematic review.

BACKGROUND: Myofibromas are rare benign neoplasms composed of myoid cells and myofibroblasts. This study aimed to systematically review case reports and a series of myofibromas (MF) and myofibromatosis (MFT) occurring in the oral and maxillofacial regions in order to describe their main clinicopathological features. METHODS: This systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Electronic searches were conducted in 2023 in four databases: MEDLINE/PubMed, Web of Science, Scopus, and EMBASE. A manual search and a search in the grey literature were also conducted. The lesions were classified as MF or MFT according to their original report. RESULTS: A total of 169 cases were included in this systematic review. Men were slightly more affected, with a painless nodule. When occurring in soft tissue, MF usually developed in the gingiva (mean age:29.23 ± 21.93 years) and when it was intra-osseous, it occurred more frequently in the posterior mandible (mean age:14.33 ± 15.62 years). MFT occurred mainly in the mandible and was predominantly described as well-circumscribed masses of spindle cells organized in fascicles with a prominent vascular activity in a hemangiopericytoma-like pattern. The lesions were mainly positive for smooth muscle actin and vimentin immunomarkers. Surgical excision was the treatment of choice in the majority of cases and recurrence was observed in only three cases. CONCLUSION: MF and MFT affect more men, with an indolent clinical course. Intra-osseous tumors and MFT seem to occur more frequently in younger individuals. These lesions seem to have a good prognosis and low recurrence.

A rare case of cervical myofibroma in an infant: A case report.

INTRODUCTION: A solitary infantile myofibroma tumor arises as a hard, painless cutaneous or subcutaneous nodule and is defined as an uncommon soft tissue neoplasm that is usually seen in childhood. CASE PRESENTATION: A nine-month-old female infant presented with a solid mass that appeared one month ago. The mass gradually increased in size within the right posterior triangle of the neck, without any local or systemic accompanying symptoms. Laboratory tests were normal. Ultrasonography revealed a homogeneous tissue mass measuring 1.5 × 3 cm, with blood flow within it. Multislice CT scan accurately localized the isolated tumor. The mass was surgically excised and found within the sternocleidomastoid muscle, without any adhesions to adjacent tissues. Histological examination of the tumor and immunohistochemical tests confirmed infantile myofibroma. CLINICAL DISCUSSION: IM is one of the most common soft tissue tumors in children and mainly consists of myofibroblasts. 90 % of IM cases are diagnosed before the age of two years. Possible therapeutic measures for this tumor include conservative management, surgical resection, chemotherapy, radiation therapy, and steroid injections into the tumor. Surgical removal of the tumor is often performed, and if it is single and completely removed, the prognosis is good with a recurrence rate of less than 10 %. CONCLUSION: Infantile myofibroma is considered a benign tumor, but it may be fatal in some cases. Each case is treated individually according to the number (single or multicentric), size, location, symptoms, and visceral involvement. Surgical resection remains the therapeutic procedure of choice in most cases.

Myofibroma of the pinna: a case report and review of the literature.

BACKGROUND: Myofibromas are rare mesenchymal tumors with a predilection for the head, neck, and oral cavity. Primarily affecting infants and young children, these tumors typically manifest as superficial painless nodules. Diagnosis is confirmed through histopathological examination of a biopsy, revealing nodules characterized by spindle cell proliferation. To our knowledge, only two cases of pinna myofibroma have been previously reported in the literature. CASE PRESENTATION: Here, we present the case of a three-year-old male who developed a myofibroma of the left auricle following trauma to the area one year earlier. The patient underwent surgical resection without any postoperative complications. The patient later returned with a lesion consistent with hypertrophic scar. CONCLUSIONS: This study aims to provide a comprehensive review of the clinical presentation, histopathologic and immunohistochemical features, and surgical management of this unique case of myofibroma of the pinna.

Misdiagnosis of synovial sarcoma - cellular myofibroma with SRF-RELA gene fusion: A case report.

BACKGROUND: Cellular myofibroma is a rare subtype of myofibroma that was first described in 2017. Its diagnosis is often challenging because of its relative rarity, lack of known genetic abnormalities, and expression of muscle markers that can be confused with sarcomas that have myogenic differentiation. Currently, scholars have limited knowledge of this disease, and published cases are few. Further accumulation of diagnostic and treatment experiences is required. CASE SUMMARY: A 16-year-old girl experienced left upper limb swelling for 3 years. She sought medical attention at a local hospital 10 months ago, where magnetic resonance imaging revealed a 5-cm soft tissue mass. Needle biopsy performed at a local hospital resulted in the diagnosis of a spindle cell soft tissue sarcoma. The patient was referred to our hospital for limb salvage surgery with endoprosthetic replacement. She was initially diagnosed with a synovial sarcoma. Consequently, clinical management with chemotherapy was continued for the malignant sarcoma. Our pathology department also performed fluorescence in situ hybridization for result validation, which returned negative for SS18 gene breaks, indicating that it was not a synovial sarcoma. Next-generation sequencing was used to identify the SRF-RELA rearrangement. The final pathological diagnosis was a cellular/myofibroblastic neoplasm with an SRF-RELA gene fusion. The patient had initially received two courses of chemotherapy; however, chemotherapy was discontinued after the final diagnosis. CONCLUSION: This case was misdiagnosed because of its rare occurrence, benign biological behavior, and pathological similarity to soft tissue sarcoma.

Unresectable infantile myofibroma discovered in utero.

The authors present a case of a proliferative nodule located beneath an infant's lower lip that was initially discovered on prenatal ultrasound and fetal magnetic resonance imaging (MRI). Biopsy revealed a smooth muscle actin-positive spindled cell proliferation with hemangiopericytoma-like vessels consistent with infantile myofibromatosis (IM). Since the location prevented surgical management, the clinicians opted to observe the lesion. Ultimately, the lesion fully regressed on its own confirming conservative management is an option for isolated IM.

Adult-Onset Multifocal Cutaneous Myofibromas: A Case Report of a Rare Entity.

Myofibromas are observed in both infantile and adult presentations, with key differences in the number and severity of lesions between these two groups. Infantile presentations encompass both indolent, isolated cutaneous lesions, as well as aggressive, multicentric presentations with visceral involvement. Adult myofibromas appear to be characterized by a single isolated cutaneous lesion, generally asymptomatic and following a benign clinical course. The occurrence of adult multifocal myofibromas has not yet been described in the literature. Here, we report a case of a 57-year-old female who presented with two minimally symptomatic soft tissue lesions on her right leg, with the pathologic findings of each lesion consistent with a cutaneous myofibroma. This case report describes a rare presentation of adult-onset multifocal cutaneous myofibromas.

Corneal Infantile Myofibromatosis Caused by Novel Activating Imatinib-Responsive Variants in PDGFRB.

Purpose: To investigate the genetic cause, clinical characteristics, and potential therapeutic targets of infantile corneal myofibromatosis. Design: Case series with genetic and functional in vitro analyses. Participants: Four individuals from 2 unrelated families with clinical signs of corneal myofibromatosis were investigated. Methods: Exome-based panel sequencing for platelet-derived growth factor receptor beta gene (PDGFRB) and notch homolog protein 3 gene (NOTCH3) was performed in the respective index patients. One clinically affected member of each family was tested for the pathogenic variant detected in the respective index by Sanger sequencing. Immunohistochemical staining on excised corneal tissue was conducted. Functional analysis of the individual PDGFRB variants was performed in vitro by luciferase reporter assays on transfected porcine aortic endothelial cells using tyrosine kinase inhibitors. Protein expression analysis of mutated PDGFRB was analyzed by Western blot. Main Outcome Measures: Sequencing data, immunohistochemical stainings, functional analysis of PDGFRB variants, and protein expression analysis. Results: We identified 2 novel, heterozygous gain-of-function variants in PDGFRB in 4 individuals from 2 unrelated families with corneal myofibromatosis. Immunohistochemistry demonstrated positivity for alpha-smooth muscle actin and ß-catenin, a low proliferation rate in Ki-67 (< 5%), marginal positivity for Desmin, and negative staining for Caldesmon and CD34. In all patients, recurrence of disease occurred after corneal surgery. When transfected in cultured cells, the PDGFRB variants conferred a constitutive activity to the receptor in the absence of its ligand and were sensitive to the tyrosine kinase inhibitor imatinib. The variants can both be classified as likely pathogenic regarding the American College of Medical Genetics and Genomics classification criteria. Conclusions: We describe 4 cases of corneal myofibromatosis caused by novel PDGFRB variants with autosomal dominant transmission. Imatinib sensitivity in vitro suggests perspectives for targeted therapy preventing recurrences in the future. Financial Disclosures: Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Intramasseteric Solitary Myofibroma: A Case Report.

Solitary myofibroma or infantile myofibroma is a rare spindle cell neoplasm that generally affects infants before the age of 2 years but cases in young children and adults have been described. Although the location of infantile myofibroma in the oral and maxillofacial region has been described, the intramasseteric location of the lesion is very uncommon. A thorough assessment of histopathological and immunohistochemical characteristics is necessary to have a correct diagnosis. Treatment relies on surgical resection. In this article, we present a rare clinical case of a 15-year-old patient with a myofibroma of the masseteric muscle and its management.

Isolated infantile myofibroma of the calvarium: Report of a case with a literature review.

OBJECTIVE: Infantile myofibromatosis is a rare entity of childhood characterized by benign myofibroblastic tumors in the soft tissues, the bones, and occasionally the viscera. Solitary skeletal lesions are relatively uncommon. Calvarial involvement should be distinguished from more aggressive tumors for appropriate treatment. METHODS: We reviewed solitary infantile myofibroma of the calvarium and discussed the relevant computed tomography and magnetic resonance imaging findings along with differential diagnosis. A case study of the frontal bone in a 5-month-old girl was also presented. RESULTS: Fourteen cases were reviewed, including the current case. Of the 13 cases with known sex, eight were male and five female. The mean age was 3.03 with an age range of 0.41-9 years. Nine of the 14 tumors were in the frontal bone. The lesions were intradiploic with tabula interna and/or externa of the calvaria involvement. The mean largest diameter was 22.3 mm. Upon computed tomography, all the lesions were expansile and lytic, and hypoattenuated, isoattenuated or occasionally hyperatenuated. Calcification was not seen. On magnetic resonance imaging, most neoplasms were hypointense on T1-weighted and T2-weighted images. Neoplasms showed hypointense signal on diffusion-weighted imaging and hyperintense on apparent diffusion coefficient, without restricted diffusion in three cases. All lesions were intensely enhanced after gadolinium administration. Treatment was total surgical resection and recurrence was not observed during follow-up. CONCLUSIONS: Infantile myofibromas are rare, typically intradiploic expansile lytic lesions with tabula interna and/or externa involvement. Distinctive imaging features include the presence of hipointense signals on T2-weighted magnetic resonance images without restricted diffusion on diffusion-weighted imaging. A slow-growing, firm, painless, and nontender mass with supportive imaging findings should raise suspicion of the disease.

Myofibroma of the body of mandible: A case report of a solitary lesion.

Myofibromas are rare benign lesions and are often found as solitary entities. The treatment of the lesion is complete excision and the recurrence is rare. A 56-year-old female presented to the Oral and Maxillofacial Surgery clinic for further evaluation and management of a solitary lesion of the right body of the mandible that was first noticed incidentally by her referring dentist. An incisional biopsy was first performed in the clinic with the diagnosis of myofibroma. The patient was then treated with complete excision of the lesion and extraction of the adjacent teeth. The final biopsy report confirmed the initial diagnosis of myofibroma. Intraosseous solitary lesion of the mandible is a rare lesion with a handful of reported cases. Uniquely, the diagnosis of myofibroma in this 56-year-old is the oldest reported case of myofibroma. There are distinct histopathological features of the lesion that distinguishes this entity from other closely resembling lesions.