Solitary, multifocal and generalized myofibromas: clinicopathological and immunohistochemical features of 114 cases

A Rare Case of Solitary Cardiac Myofibroma in an Infant

Solitary myofibromas are rare, benign, mesenchymal tumors typically found in the head and neck regions. We report an exceptionally rare case of a solitary cardiac myofibroma and its short-term management and outcome. A two-month-old infant was referred due to a murmur. Echocardiography revealed a 2 × 1 cm solitary mass originating from a mitral papillary muscle, causing severe regurgitation. Magnetic resonance imaging showed the mass to be homogeneous on T1, hyperintense on T2, and hypointense on first-pass perfusion imaging with no enhancement on delayed postcontrast imaging. The mass was surgically excised partially due to its involvement with the mitral valve. Postoperative recovery was uneventful, with echocardiography four months later showing no tumor recurrence and trivial mitral regurgitation. This report provides valuable imaging and pathology examples to aid in the recognition of this rare tumor and demonstrates that successful surgical excision is possible, even with significant cardiac involvement.

Rhabdomyosarcoma in children and young adults

Rhabdomyosarcoma (RMS) is the most common soft tissue malignancy in childhood, accounting for 3% of all pediatric malignancies and 50% of all pediatric soft tissue sarcomas. In adolescents and young adults (AYA) however, RMS comprises only 6.5% of all soft tissue sarcomas. Historically, diagnosis and treatment of RMS was based on histologic recognition of the alveolar subtype, which was associated with a worse prognosis. Within the past 20 years, the biologic characteristics of RMS have become clearer, with canonical fusion drivers, PAX3/7::FOXO1, characterizing the alveolar subtype (ARMS) and in turn associated with poor outcome, while chromosomal gains/losses in addition to RAS pathway alterations characterize the embryonal subtype (ERMS). Accordingly, detection of a FOXO1 gene fusion has become a commonplace diagnostic and prognostic tool allowing tumors to be treated based on presence or absence of a FOXO1 gene fusion. However, these cytogenetic and molecular alterations represent only a portion of the molecular landscape found in RMS, and other alterations are found with increasing frequency in various subsets of RMS. Clinical trials basing risk stratification on the presence or absence of the canonical PAX3/7::FOXO1 fusions have had success in identifying the poor responders. Due to poor outcomes, the presence of MYOD1 and TP53 alterations which are common in spindle cell sclerosing RMS (SSRMS) and RMS with anaplasia have also been integrated into trial risk stratification. Therefore, complete histologic and immunophenotypic characterization remain important to better recognize and study these rare subsets of RMS. This article will discuss the challenges of RMS classification including how to combine morphologic, immunophenotypic and molecular data to arrive at an integrated diagnosis. The use of newer techniques such as liquid biopsy and methylation profiling, will also continue to shape the classification of RMS and may further refine risk stratification and prognosis.

A germline PDGFRB splice site variant associated with infantile myofibromatosis and resistance to imatinib

PURPOSE

Infantile myofibromatosis is characterized by the development of myofibroblastic tumors in young children. In most cases, the disease is caused by somatic gain-of-function variants in platelet-derived growth factor (PDGF) receptor beta (PDGFRB). Here, we reported a novel germline intronic PDGFRB variant, c.2905-8G>A, in 6 unrelated infants with multifocal myofibromatosis and their relatives.

METHODS

We performed constitutional and tumor DNA and RNA sequencing to identify novel variants, which were subsequently characterized in cellular assays.

RESULTS

All patients had multiple skin nodules, 4 had bone lesions, and 2 had aggressive disease with bowel obstruction. The c.2905-8G>A substitution creates an alternative acceptor splice site in intron 21, inserting 2 codons in the PDGFRB transcript. Functional studies revealed that the splice change induced a partial loss of function, contrasting with previously described variants. In 4 tumor samples, we identified a second somatic hit at position Asp850 in PDGFRB exon 18, triggering constitutive receptor activation and resistance to imatinib. In addition to vinblastine and methotrexate, 2 patients received imatinib without objective response. One of them switched to dasatinib with concomitant improvement.

CONCLUSION

This splice-site PDGFRB variant favors the development of myofibroma, featuring an acquired oncogenic variant in the same gene and resistance to targeted 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.

Incidental Solitary Myofibroma in a Young Adult Female Patient: A Case Report and Comprehensive Literature Review of Myofibroma in Adults

Myofibroma is a rare mesenchymal tumor typically observed in children, with only a few reported cases in adults. It can be easily mistaken for more common benign lesions, making it essential to include them in the differential diagnosis of soft tissue masses. This case report presents a rare instance of myofibroma in a young adult, and a comprehensive review of the literature presenting case reports and case series of myofibroma cases in the head and neck regions of adult patients aged > 18 years. A 22-year-old woman presented with a gradually enlarging, painless mass on the right side of her neck which had been developing over the course of two years. An ultrasound initially identified a 1×2 cm lipoma; however, during surgery, a fibrous soft tissue mass was discovered extending beneath the sternocleidomastoid muscle. The mass was found to be closely associated with the posterior auricular nerve. Despite its proximity to the nerve, the tumor was successfully excised, while preserving the nerve. Histopathological analysis confirmed a diagnosis of myofibroma. This case highlights the rare occurrence of myofibromas in adults and emphasizes the importance of considering this diagnosis when evaluating soft-tissue masses. Even when imaging suggests a benign lesion, surgical intervention may yield unexpected results. Accurate diagnosis through histopathology is essential, and careful surgical techniques, including nerve preservation, play a critical role in successful management. Long-term follow-up is necessary to ensure the absence of tumor recurrence.

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.

Pediatric Gnathic Bony and Mesenchymal Tumors

Evaluation of bone pathology within the head and neck region, particularly the gnathic bonesis is complex, demonstrating unique pathologic processes. In part, this variation is due to odontogenesis and the embryological cells that may be involved, which can contribute to disease development and histologic variability. As with any boney pathosis, the key is to have clinical correlation, particularly with radiographic imaging prior to establishing a definitive diagnosis. This review will cover those entities that have a predilection for the pediatric population, and while it is not all inclusive, it should serve as a foundation for the pathologist who is evaluating bony lesions involving the craniofacial skeleton.

A retrospective study comprising 228 cases of pediatric scalp and skull lesions

BACKGROUND

Most neurosurgery presentations in children present with a mass that may be scalp and skull lesions, including neoplastic and congenital malformed structural lesions, respectively. Clinicians should make early diagnoses and identify cases requiring surgical intervention promptly to help achieve a better prognosis.

METHOD

This study retrospectively reviewed studies on children's scalp and skull lesions within a pediatric medical center's department of neurosurgery. The detailed clinical information and pathological types of these cases were scrutinized.

RESULT

A total of 228 children's scalp and skull lesions with clinical information and identified histopathology types were summarized. The most common scalp and skull lesions were benign dermoid cysts; malignant types were rare but can occur in children.

CONCLUSION

Based on the combined clinical symptoms and image information, children's scalp and skull lesions should be diagnosed early. Malignant scalp and skull lesions/other special cases should be treated seriously.

Solitary, adult-onset, intraosseous myofibroma of the rib: a case report and literature review

Myofibromas are rare benign tumors with myofibroblastic origin. They occur especially in cutis and subcutaneous tissue of the head and the neck, less frequently on the extremities. Myofibromas grow very slowly and are often painless, which is why patients often present relatively late. In the literature, there were many reports about intraosseous myofibromas of the craniofascial bones but reports of the trunk and extremities in adults are very rare. The authors present a very rare case of an intraosseous myofibroma of the ribs resulting in pathological fracture, including a research of literature from other cases of intraosseous myofibromas of the trunk or extremities.

Infantile Fibrosarcoma and Other Spindle Cell Neoplasms of Infancy. A Review of Morphologically Overlapping yet Molecularly Distinctive Entities

BACKGROUND

Regardless of age at presentation, many soft tissue neoplasms have overlapping histopathologic and immunophenotypic features to serve as a diagnostic challenge.

CASE REPORT

We reported a case of a spindle cell neoplasm in an infant, which was initially considered a vascular anomaly clinically and an eventual biopsy revealed marked inflammation with a spindle cell component that was resolved as an infantile fibrosarcoma with an ETV6 break-apart.

CONCLUSION

The context of this case lead to a further consideration of various other spindle cell neoplasms arising predominantly in the soft tissues during the infancy period as defined by the first two years of age. Though sharing similar morphologic features, these tumors can be categorized into several molecular genetic groups, which have provided both diagnostic and pathogenetic insights as well as treatment options in some cases.

Infantile Myofibroma: A Report of Two Cases with Differential Diagnoses

Infantile myofibromas (IMs) are benign soft-tissue tumors of children. They are of fibroblastic-myofibroblastic origin and show considerable morphological overlap with other spindle cell neoplasms. Here, we present two cases of solitary myofibromas, one in a neonate and one in a 2-year-old girl. A 2-day-old girl presented with severe respiratory distress and died during intubation. At autopsy, a myofibroma involving the oropharynx with extension up to the larynx was noted. Second case was a 2-year-girl with a myofibroma in the hard palate. IM must be differentiated from other benign and malignant spindle cell tumors of infancy and childhood. Oropharyngeal myofibroma should be considered in the differentials of neonatal respiratory distress.

Infantile Myofibroma: A Series of 2 Cases with Special Reference to Cytological Features

BackgroundInfantile myofibromas (IM) are benign soft tissue lesions of childhood and represent a significant portion of the benign spectrum of fibroblastic-myofibroblastic tumors. Cytological diagnosis of these tumors can be challenging because of overlapping morphology and limited case report descriptions. We describe the cytological features and the cytological differential diagnoses.Case reportWe describe cytological features of two IMs. The main features were the presence of loose clusters and dispersed bland myofibroblasts in varying stages of maturation with traversing blood vessels and myxoid stroma. The cells typically lacked features of atypia, mitoses and significant pleomorphism.ConclusionDiagnosis of IM on the basis of cytology alone can be tricky and definitive diagnosis should be made only after correlating the cytological features with histology. However, bland morphology of differentiating myofibroblasts can aid in cytological diagnosis and help to exclude other malignant spindle cells neoplasms needing preoperative chemotherapy.

Infantile myofibromatosis: Excellent prognosis but also rare fatal progressive disease. Treatment results of five Cooperative Weichteilsarkom Studiengruppe (CWS) trials and one registry

BACKGROUND

Infantile myofibromatosis (IM) is a rare benign soft tissue tumor and often a self-limiting disease but rarely includes life-threatening complications. Little is known about optimal treatment of primary localized (LD) and multifocal disease (MFD).

METHODS

Treatment and outcome of 95 children with IM registered within five Cooperative Weichteilsarkom Studiengruppe (CWS) trials and one registry (1981-2016) were evaluated.

RESULTS

LD was diagnosed in 71 patients at a median age of 0.4 years (range 0.0-17.7). MFD was present in 24 patients. The mainstay of treatment was watch-and-wait strategy (w&w) after initial biopsy or resection. Low-dose chemotherapy (CHT) was administered to 16/71 (23%) patients with LD and eight of 24 (33%) patients with MFD, imatinib was added in two. A delayed resection was possible in eight of 71 (11%) and five of 24 (21%) patients with LD and MFD, respectively. Overall, patients were alive in complete remission (n = 77) and partial remission (n = 10) at a median follow-up time of 3.4 years after diagnosis (range 0.01-19.4); no data available (n = 5). Three patients died of progressive disease (PD) despite CHT. Gender, tumor size, and location correlated with a favorable event-free survival (EFS) in patients with LD. The 5-year EFS and overall survival of patients with LD were 73% (±12, confidence interval [CI] 95%) and 95% (±6, CI 95%), respectively; for MFD 51% (±22, CI 95%) and 95% (±10, CI 95%).

CONCLUSION

Prognosis is excellent in patients with LD and MFD. Targeted treatment needs to be evaluated for rare fatal PD.

Fibroma of tendon sheath is defined by a USP6 gene fusion-morphologic and molecular reappraisal of the entity

Fibroma of tendon sheath (FTS) is an uncommon benign myofibroblastic neoplasm that arises in association with tenosynovial tissue. Fusions of the USP6 gene have been recently documented in a proportion of so-called "cellular FTS" but not in "classic FTS". It remains unknown whether FTS can be defined by a USP6 fusion, regardless of cellularity, and what are USP6 fusion-negative "cellular FTS". Furthermore, FTS with low cellularity seems to be frequently confused with desmoplastic fibroblastoma. We performed a comprehensive analysis, including targeted RNA sequencing, of 58 consecutive cases originally diagnosed as FTS (n = 49), desmoplastic fibroblastoma (n = 6), or nodular fasciitis (n = 3); the latter two at the predilection sites for FTS. After review of the original slides, 28 lesions were morphologically classified as FTS (13 "classic" and 15 "cellular") and 23 as desmoplastic fibroblastoma. Among originally diagnosed FTS at the more cellular end of the spectrum, we identified seven lesions that shared many morphologic features of FTS but, in addition, showed several distinct morphologic features consistent with myofibroma, such as myoid appearance, branching thin-walled vessels, and perivascular growth. Targeted RNA sequencing showed a USP6 fusion in 17 of 18 analyzed FTS, regardless of cellularity, 0 of 5 desmoplastic fibroblastomas and 0 of 4 myofibromas. MYH9, COL1A1, and ASPN were identified as fusion partners in three cases each, and MIR22HG, CTNNB1, SPARC, CAP1, EMP1, LINC00152, NR1D1, and RAB1A in a single case each. FTS, regardless of cellularity, can be defined by a USP6 fusion with a variety of fusion partners. More cellular lesions exhibiting some morphologic features of FTS but lacking a USP6 fusion tend to be myofibromas.

Novel COL4A1-VEGFD gene fusion in myofibroma

Myofibroma is a benign pericytic tumour affecting young children. The presence of multicentric myofibromas defines infantile myofibromatosis (IMF), which is a life‐threatening condition when associated with visceral involvement. The disease pathophysiology remains poorly characterized. In this study, we performed deep RNA sequencing on eight myofibroma samples, including two from patients with IMF. We identified five different in‐frame gene fusions in six patients, including three previously described fusion transcripts, SRF‐CITED1, SRF‐ICA1L and MTCH2‐FNBP4, and a fusion of unknown significance, FN1‐TIMP1. We found a novel COL4A1‐VEGFD gene fusion in two cases, one of which also carried a PDGFRB mutation. We observed a robust expression of VEGFD by immunofluorescence on the corresponding tumour sections. Finally, we showed that the COL4A1‐VEGFD chimeric protein was processed to mature VEGFD growth factor by proteases, such as the FURIN proprotein convertase. In conclusion, our results unravel a new recurrent gene fusion that leads to VEGFD production under the control of the COL4A1 gene promoter in myofibroma. This fusion is highly reminiscent of the COL1A1‐PDGFB oncogene associated with dermatofibrosarcoma protuberans. This work has implications for the diagnosis and, possibly, the treatment of a subset of myofibromas.

An unusual case of a solitary cardiac myofibroma causing severe right ventricular outflow tract obstruction in an infant

Cardiac tumours are relatively uncommon, particularly in children. Myofibroma is an extremely rare variety of cardiac tumour, which nearly always arises in the context of infantile myofibromatosis. Herein, we present a case of a solitary cardiac myofibroma causing right ventricular outflow tract obstruction in a 2-month-old male infant.

Solitary Testicular Myofibroma in a Rabbit

Myofibromas are mesenchymal tumours of myofibroblastic origin that occur in solitary or multicentric forms. Solitary benign myofibromas mainly occur on the head and neck, especially in the subcutaneous region. They rarely occur in visceral organs in humans, but visceral myofibroma has not been reported in animals. We now report a case of testicular myofibroma in a 6-year-old rabbit in which orchiectomy revealed an enlarged testis with a multinodular surface. The cut surface of the testis showed a thick, homogeneous white-yellow mass surrounding the testicular parenchyma. Histopathologically, the mass was composed of collagen and eosinophilic fascicles of spindle cells that were immunopositive for α-smooth muscle actin but not desmin, S-100 or von Willebrand factor. These features distinguished the myofibroma from other spindle cell tumours. To the best of our knowledge, this is the first report of solitary testicular myofibroma in any animal species.

Myofibroma/myofibromatosis: MDCT and MR imaging findings in 24 patients with radiological-pathological correlation

Background

The aim of this study was to characterize the radiological features of myofibroma on multidetector computed tomography (MDCT) and magnetic resonance imaging (MRI) and correlate the imaging findings with pathologic features.

Methods

The radiological findings of 24 patients with 29 myofibromas were retrospectively reviewed. All images were evaluated with emphasis on density, signal intensity, hypointense area, and enhancement, correlating these with pathologic findings.

Results

On plain MDCT scan, 4(26.7%) tumors were homogeneous isodensity, 4(26.7%) tumors were heterogeneous hyperdensity, and 7(46.7%) tumors were heterogeneous hypodensity. On contrast-enhanced MDCT scan, all tumors (9/9) showed heterogeneous enhancement with moderate in 3(33.3%) and marked in 6(66.7%) tumors, and their enhancements were higher compared to adjacent skeletal muscle (P = 0.0001). On MRI, heterogeneous slight hyperintensity, homogeneous slight hyperintensity, and heterogeneous hypointensity on T1-weighted imaging (T1WI) were observed in 14(82.3%), 1(5.9%) and 2(11.8%) tumors, respectively. On T2-weighted imaging (T2WI) and fat-suppressed (FS) T2WI, all tumors demonstrated heterogeneous hyperintensity. All tumors showed heterogeneous marked enhancement on FS contrast-enhanced T1WI. On T1WI, T2WI, FS T2WI, and FS contrast-enhanced T1WI, irregular strip or/and patchy hypointensities were found in 16(94.1%), 12(100%), 17(100%) and 17(100%) tumors, respectively, and pseudocapsule was seen in 5(29.4%) tumors. The hypointensities and pseudocapsule on MRI were exactly corresponding to pathological interlacing collagen fibers and fibrosis. The age of the recurrent group was lower than that of the non-recurrent group (P = 0.001) and the tumors without pseudocapsule were more likely to recur than those with pseudocapsule (P = 0.034).

Conclusion

Myofibromas are characterized by heterogeneous density or signal intensity, with moderate or marked enhancement. The hypointensities and pseudocapsule on MRI may be helpful in diagnosis, and the absence of pseudocapsule and younger age may be risk factors for tumor recurrence.

Infantile Myofibroma: Case Report and Review of the Literature

We report a case of solitary infantile myofibroma (IM) with partially CD34-positive neoplastic cells on the back of a newborn boy. Ultrasonography showed a multilocular mass with a hypoechoic center surrounded by an isoechoic rim. Histopathological analysis revealed that the lesion was composed of small, round cells that were tightly packed and uniform. The cells had oval nuclei and were pale, CD34-positive, and richly cellular. They had interlacing fascicles of spindle cells with features of myofibroblasts with α-smooth muscle actin positivity. We speculate that neoplastic cells in most IMs differentiate towards myofibroblasts. However, in rare cases, their differentiation is more primitive and they express CD34, with or without α-smooth muscle actin expression.

Solitary intraosseous myofibroma of the ilium in an adult patient: A case report and literature review

BACKGROUND

Myofibroma is a rare benign tumor typically occurring in the skin and subcutaneous tissues of the head and neck in infants and young children. The incidence of solitary intraosseous and adult myofibroma is extremely low. Although there have been a few reported cases of solitary intraosseous myofibroma in adult patients, most of these cases involved the craniofacial bones.

METHODS

We present the case of a 64-years-old woman presenting with minimal pain of the right buttock and groin.

RESULT

Radiographs and computed tomography showed a huge tumor spreading around the ilium, and non-uniform calcifications were noted inside the tumor. Iliac tumor biopsy was conducted, and intraosseous myofibroma was suspected. We performed surgical resection of the mass, and a final diagnosis of myofibroma with metaplastic bone production was made.

CONCLUSION

We have presented an extremely rare case of solitary intraosseous myofibroma in an adult patient.

Solitary intramuscular myofibroma in an adult: Case report and MR imaging findings

Myofibroma is a benign, soft tissue neoplasm that predominantly affects infants and young children. Most occur in the skin or subcutaneous tissues, with a predilection for the head and neck regions. We describe the magnetic resonance (MR) imaging and histophathologic findings of a rare case of intramuscular myofibroma of the right deltoid in a healthy 30-year-old male. MR imaging revealed a well-circumscribed intramuscular mass, with isointense signal on T1-weighted images, hyperintense signal on T2-weighed images, and a "target-sign" with peripheral rim enhancement after gadolinium administration. The lesion was surgically excised with no complications, and the histopathologic analysis revealed the typical morphologic and histochemical markers of a myofibroma. We conclude that, although rare, myofibroma can be considered in the differential diagnosis of adults with lesions the above signal characteristics.

Odontogenic myxomas lack PDGFRB mutations reported in myofibromas

BACKGROUND

The molecular pathogenesis of odontogenic myxoma has not been established yet. Considering that odontogenic myxoma may show myofibroblastic differentiation and myxoid areas can be observed in intra-osseous myofibromas, we tested the hypothesis whether both tumors share a common molecular profile. As recent studies have reported PDGFRB recurrent driver mutations in myofibroma, we evaluated PDGFRB mutations in odontogenic myxomas.

METHODS

A convenience sample of 15 odontogenic myxomas cases was selected. We direct sequenced PDGFRB exons 12 and 14, where p.R561C (c.1681C>T) and p.N666K (c.1998C>G) hotspot mutations have been reported among others in single and/or multiple myofibromas.

RESULTS

All 15 odontogenic myxoma samples were successfully sequenced, and all 15 had wild-type sequences for the PDGFRB mutations investigated.

CONCLUSION

Our findings suggest that PDGFRB mutations do not play a role in odontogenic myxoma pathogenesis, which might be helpful in the differential diagnosis of challenging cases.

[Pediatric tumors with spindle cell morphology]

Spindle cell tumors in childhood are rare lesions with a heterogeneous morphological picture and clinical course, ranging from benign lesions to fully malignant tumors. The clinical assessment of these tumors is often challenging since some of them show fast growth dynamics but are utterly benign, while a subset of slow-growing tumors can represent malignant entities. Due to the rarity of these tumors as well as the overlapping morphology and the often uncharacteristic immunohistochemical profiles, the pathologic diagnosis is often also difficult. This review gives an overview of some of the more common pediatric spindle cell tumors. In addition to the morphological features and immunohistochemical aspects, specific molecular changes are discussed. Here, some of the newly described translocations that may imply therapeutic options, are presented.

Infantile myofibromatosis: review of imaging findings and emphasis on correlation between MRI and histopathological findings

BACKGROUND

Infantile myofibromatosis (IM) is the most common fibrous tumor of infancy. MRI is considered the gold standard in IM evaluation. Very little has been published about IM with histopathology correlation in the pediatric age.

PURPOSE

Describe imaging findings in IM and correlate MRI findings with histopathology.

MATERIAL AND METHODS

Imaging findings of 17 patients with IM were retrospectively analyzed including CT, US and MRI. Signal characteristics on T1-, T2-weighted and STIR imaging, extent of T2-hyperintensity, degree & pattern of enhancement, diffusion restriction, location & margins, & involvement of adjacent structures were tabulated. Histopathology findings included cellularity, collagenization, myxoid changes, atypia, mitosis & microscopic invasion. Established grading scores were utilized.

RESULTS

Relative to normal skeletal muscle, on T1-weighted imaging, 9 lesions had similar signal while the remaining had a mixture of iso & hypo intensity; whereas on T2-weighted and STIR imaging, all 12 lesions demonstrated a mixture of iso, hypo & hyperintensity. T2-hyperintensity was grade 2 in one, grade 3 in 8 & grade 4 in 3 lesions. Intensity of enhancement was grade 2 in one, grade 3 in 8 & grade 4 in 3 lesions. Enhancement was predominantly peripheral in all 12 lesions. Extent of T2-hyperintensity & degree of enhancement corresponded to variable grades on histopathology. CT and US showed nonspecific findings.

CONCLUSION

On MRI, IM has a mixture of signal intensity with predominant hyperintense signal on T2W images. However various signal & enhancement features correlated poorly with specific histopathologic grades.

Nonepithelial Tumors and Tumor-like Lesions of the Skin and Subcutis in Children

This overview of mesenchymal tumors presenting in the skin and/or subcutis in children brings together the range of neoplasms and hamartomas which are seen in this age-group. It is not surprising from the perspective of the pediatric or general surgical pathologist that vascular anomalies, including true neoplasms and vascular malformations, are the common phenotypic category. Since there is considerable morphologic overlap among these lesions, clinicopathologic correlation may be more important than for many of the other mesenchymal tumors. The skin and subcutis are the most common sites of clinical presentation for the infantile myofibroma which is the most common of fibrous mesenchymal tumors in children. Several of the other mesenchymal tumors are more common adults-like dermatofibrosarcoma protuberans, but nonetheless have an important presence in children, even as a congenital neoplasm. A lipomatous tumor in a young child should be considered as a possible manifestation of an overgrowth syndrome.

Spontaneous involution (regression) of a solitary cutaneous myofibroma in an adult patient

Myofibromas are unusual benign tumors most commonly seen in infant children. Clinical involution of the tumor often occurs within the first few years of life. Solitary cutaneous myofibroma is the synonymous adult counterpart of infantile myofibromatosis. Although solitary myofibromas have been reported in patients of all ages, only the infantile variant is believed to regress spontaneously. There are only a few case reports of adolescent and young adult patients with regressing solitary lesions that have been described in the literature to date. We report a 71-year-old male with spontaneous regression of solitary cutaneous myofibroma. The residual lesion was excised and to date has not recurred. This report describes the historical, clinical and histopathological features of adult myofibromas and a novel manifestation that may guide future clinical considerations when approaching solitary tumors with regressive features.

A rare erosive orbital mass in a child: Case report of myofibroma

PURPOSE

To present the clinical, histological, and radiographic findings of a case of orbital myofibroma in an unusual location. The literature is reviewed and the clinical relevance discussed.

METHODS

A 5-year-old boy was examined with a 1.5-month history of progressive swelling in the left supraorbital region.

RESULTS

Examination revealed a firm, painless mass in the supralateral region of the left orbit with slight reddish discoloration of the overlying skin. Computerized tomography (CT) scan images showed a well demarcated, homogenous, solid mass with extension to the lacrimal gland region and adjacent to frontal bone erosion. The mass was surgically excised and was confirmed to be myofibroma in diagnostic histological studies. There has been no evidence of recurrence in the first year after surgery.

CONCLUSIONS

Clinical appearance and imaging findings are unspecific for this tumor, and histological examination still remains the definite method of diagnosis. Therefore, it is important to be able to differentiate myofibromas from other malignant tumors with a similar presentation in pediatric patients to avoid mismanagement.

Putative Intravascular Myofibroma Mimicking a Vascular Malformation With Phleboliths

Myofibroma is a rare, benign myofibroblastic tumor that commonly presents at birth or in early infancy, usually as a painless, slow-growing, solitary, nodular mass. We present a case of a 40-year-old woman with a painful, solitary, myofibroma on the right elbow. The unique features of this case include age and gender of the patient, site, pain on presentation, tumor morphology, and putative intravascular nature of the tumor.

Perineural Pseudoinvasion: An Unusual Phenomenon in Nonmalignancies

Perineural invasion (PNI) is characterized as tumoral or nontumoral cells invading in or around the nerves. The neural invasion is considered as a histopathologic characteristic for malignancy and is considered a mechanism for its spread. Both of these patterns usually portend a poor prognosis and very often are markers to prompt additional treatment. There are also some nonmalignancies representing PNI, including benign neoplasms, mimicking lesions, and disorders, such as chronic pancreatitis and endometriosis. The previously recommended terms are PNI, spread, or infiltration. To distinguish PNI in malignancies from that in nonmalignancies, we propose the term "perineural pseudoinvasion" to convey their nonmalignant behavior. Despite the low prevalence, awareness of this benign pseudoinvasion is necessary to avoid aggressive treatment and its misdiagnosis with malignancies. We conducted a systematic search in PubMed and Scopus databases up to December 2015 to find articles reporting PNI in nonmalignancies. After screening, 63 articles were identified as relevant. There were also 2 review articles discussing PNI in nonmalignancies. We aim to present an overview of the perineural pseudoinvasion and to discuss the previously published review articles.

Extracalvarial Composite Infantile Myofibromatosis: Case Report and Literature Review

Infantile soft tissue tumors of the head are very rare and the majority of them are myofibromas. The authors present the case of a 1-day-old boy with a scalp tumor with several distinct histopathological features including myofibroma, hemangiopericytoma, and fibrosarcoma consistent with the diagnosis of composite infantile myofibromatosis. Genetic testing was negative for trisomy 17, translocation (12; 15), FUS, and ETV6 translocations. Despite the ominous histopathological features, the clinical course was benign. The authors review here available literature concerning current concepts of making the diagnosis of composite infantile myofibromatosis and discuss treatment options.

Transcatheter management of mid-aortic syndrome secondary to myofibroma presenting in infancy with severe left ventricular dysfunction: a case report

In this study, we summarise a case of a myofibroma causing mid-aortic syndrome due to obstruction of the distal thoracic and abdominal aorta leading to severe left ventricular dysfunction. The patient was managed with percutaneous intervention via balloon dilation and stent placement. On follow-up, the patient has normalisation of ventricular function, is off anti-hypertensives, and is being monitored for re-stenosis.

Ruptured Infantile Myofibroma of the Head Presenting in a Neonate: Case Report and Review of the Literature

BACKGROUND

Infantile myofibroma/myofibromatosis (IM/M) is a myofibroblastic proliferative disorder often seen in infants and children. IM/M can result in congenital tumors of the head and neck and may occasionally present to the neurosurgeon.

CASE DESCRIPTION

We report a case of a solitary ruptured myofibroma of the head in a newborn patient. The lesion was initially suggestive of encephalocele. We describe the presentation and management of this patient, including relevant imaging, histopathologic evaluation, and surgical technique. We subsequently review the literature of IM/M of the head and neck, highlighting the 3 forms of the condition, each requiring a distinct management strategy.

CONCLUSIONS

Although this tumor rarely presents to the neurosurgeon, it may do so in the process of ruling out other more dangerous conditions. It is therefore important to consider this diagnosis in masses that occur in the head and neck of newborns.

Solitary, adult-onset, intraosseous myofibroma of the finger: report of a case and review of literature

Myofibroma is a rare benign neoplasm of myofibroblastic origin. It typically occurs in the skin and subcutaneous tissues of the head and neck in infants and young children as multicentric lesions known as infantile myofibromatosis. Intraosseous myofibromas are very rare and are typically destructive lesions that predominantly affect craniofacial bones in the setting of myofibromatosis. Solitary, intraosseous myofibromas in adults are exceedingly rare. Herein, we report a myofibroma involving the middle phalanx of the right index finger in a 58-year-old man who presented with a pathologic fracture. Twelve other cases of adult-onset, intraosseous myofibroma were compiled from the English language literature and integrated with this report.

Head and neck solitary infantile myofibroma: Clinicopathological and immunohistochemical features of a case series

Infantile myofibroma is a rare mesenchymal benign tumor mostly found in the head and neck region. The aim of this study was to describe a small case series of head and neck solitary infantile myofibroma, emphasizing the importance of the histopathological and immunohistochemical features, and the potential diagnostic challenges. For the study, clinical and imaging data were obtained from the medical records. All cases were histologically reviewed, and immunohistochemical analyses were performed to confirm the diagnosis. Four cases of head and neck solitary infantile myofibroma were identified. All patients were females and presented a mean age of 3 years old (ranging from 2 to 6 years). The site of the tumors were the mandible, right cheek, subcutaneous tissue adjacent to basal cortical of the mandible and upper anterior gingiva. No symptoms, such as pain or paresthesia, were reported. Computerized tomography revealed well-delimited tumors. All tumors were positive for vimentin and alpha-smooth muscle actin. All patients underwent surgical excision and no signs of recurrence were observed after long-term follow-up. In summary, head and neck solitary infantile myofibromas are rare and present excellent prognosis. The correlation between clinical, histopathological and immunohistochemical features are essential for a correct diagnosis.

Myofibroma of the cervical spine presenting as brachialgia

Myofibromas are rare, benign tumors of myofibroblasts. Their occurrence in adults, involving bone outside of the head and neck, is especially uncommon. The authors report the case of a 34-year-old woman who presented with left-sided brachialgia. Magnetic resonance imaging identified an expansile soft-tissue lesion of the C6-7 facet joint. En bloc resection via a left posterior midline approach was undertaken. Histopathological analysis confirmed the lesion to be a myofibroma. Brachialgia resolved following surgery and there is no evidence of recurrence at 20 months follow-up. Myofibroma is a rare cause of primary soft-tissue tumor of the spine. Surgical excision remains the mainstay of treatment.

Solitary intraosseous myofibroma of the tibia in an adult patient: A case report

Myofibromas are mesenchymal tumors showing myofibroblastic differentiation and found most frequently in the head and neck region. While several cases of myofibromas have been reported in adults, they have not been described in long bones of the appendicular skeleton. We describe an otherwise healthy young woman who presented with a progressive incapacitating pain in her right shin. Imaging studies revealed a well-circumscribed osteolytic lesion with slight marginal sclerosis confined to the proximal tibia metaphysis, without a soft tissue component. Surgical intervention was performed and histological examination identified a myofibroma.

This case represents an extremely rare occurrence of an intraosseous myofibroma involving a long bone in an adult patient. Although solitary myofibroma is a rare lesion in the skeletal bones of adults we believe it should be included in the differential diagnosis of a solitary lytic mass in bone, especially if it is associated with pain.

Mandibular swelling in a 5-year-old child--mandibular myofibroma

A 5-year-old girl of African descent presented with a history of progressive painless swelling on the right side of the jaw since the past 2-3 months. Orthopantomogram showed a radiolucent lesion near the angle of the mandible. Subsequent CT scan revealed a 2 cm×2 cm radiolucent lesion with intense periosteal reaction surrounding the lesion and destruction of the overlying cortex. Radiological perplexity aroused regarding the possibility of eosinophilic granuloma or some other malignant lesion. Incisional biopsy performed and microscopy showed spindle cell tumor. Immunohistochemistry confirmed it as myofibroma. Myofibroma is a rare benign tumour involving mesenchyme. Involvement of the mandible is rare. Radiological presentation with strong periosteal reaction is a rarity and has rarely been reported in the medical literature. We conclude that intraosseous myofibroma can sometimes have strong periosteal reaction and careful radiological evaluation is a prerequisite for accurate diagnosis and to avoid unnecessary aggressive therapy.