Myofibromas and myofibromatosis of the oral region: A clinicopathologic analysis of 79 cases

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.

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.

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.

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.

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.

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.

Post-surgical thyroid bed myofibroma simulating a recurrent papillary thyroid carcinoma: A case report and review of the literature

RATIONALE

Myofibromas are rare benign spindle cell tumors of the soft tissue, bone, or internal organs that occur at any age. Here, we report a post-surgical thyroid bed myofibroma that mimicked a papillary thyroid carcinoma.

PATIENT CONCERNS

A 56-year-old male presented with a mass in the thyroid surgical bed, detected 3 years post thyroidectomy following papillary carcinoma.

DIAGNOSIS

Thyroid ultrasonography revealed a well-defined, lobulated, hypoechoic, solid nodule, with large rod-like echogenic foci in the thyroid surgical bed. The development of a postoperative suture granuloma was considered. However, ultrasonography performed 12 months later showed a marked increase in the lesion size. Two fine needle aspiration cytology yielded nondiagnostic results.

INTERVENTION

Considering the possibility of local tumor recurrence, surgical resection was performed.

OUTCOME

The diagnosis of a myofibroma was confirmed, and no additional treatment was administered.

LESSONS

It is challenging to differentiate lesions occurring on the thyroid surgical bed after surgery, from recurrent thyroid cancer. A lesion measuring 6 mm, with a degree of punctate echogenicity, suggests tumor recurrence. Moreover, myofibromas are extremely rare. This case highlights that it is advisable to perform a core needle biopsy in cases of nondiagnostic fine needle aspiration results.

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.

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 Recurrent Cheek Mass

Solitary infantile myofibroma is a benign fibrous tumor occurring in early childhood. Although rare, it is the most common benign fibrous tumor of infancy. The clinical course of the disease is almost uniformly good since most tumors regress spontaneously. When indicated, conservative surgical excision is the treatment of choice, with a low recurrence rate. We present a case of solitary infantile myofibroma that recurred after three attempts of surgical excision, questioning the reported recurrence rate and the standard of care in recurrent solitary infantile myofibroma.

A rare low-grade myofibroblastic sarcoma in lower jaw with the resemblance to benign lesions

Background

Low-grade myofibroblastic sarcoma (LGMS) is a rare solid infiltrative soft tissue tumor with a predilection for the head and neck region.

Case presentation

We report the diagnostic steps of a fast-growing lesion of the lower left jaw in a 45-year-old otherwise healthy woman. A first biopsy and subsequent histopathological examination showed potential differentials of a benign myofibroma, benign nodular fasciitis or an LGMS. This diagnostic overlap was a challenge for the decision of the further treatment approach. The treatment consisted of a segmental en bloc resection of the mandible including the second premolar, first and second molar. Histopathological examination of the resected tumor confirmed an LGMS.

Conclusion

The histopathologic resemblance of LGMS to a range of benign and reactive tumors may lead to misdiagnosis and mistreatment. The rarity of LGMS explains the lack of established treatment protocols. This case shows the importance of adequate clinical decisions, expertise in the histopathology of rare tumors and interdisciplinary exchange to achieve state-of-the-art patient management.

Mandibular Myofibroma and Severe Trismus: A Complex Case and Review of Complications

A female child was investigated for insidious onset of temporomandibular joint dysfunction and trismus in the setting of a mandibular myofibroma. Myofibromas, benign mesenchymal neoplasms composed of spindle cells, are rarely found in the oral cavity, most commonly in the mandible. These lesions are historically described as indolent with a high cure rate and minimal recurrence rates following surgical resection. The patient initially presented with concerns regarding snoring, retrognathia, and jaw ankylosis, as well as a history of trouble latching as an infant but without obvious physical deformities. Imaging revealed a large expansile lytic mass of the mandible, but no temporomandibular joint involvement; surgical biopsy evidenced myofibroma, and the lesion was resected. Over the course of disease, the lesion continued to expand, and the patient’s maximal incisal opening continued to decrease despite conservative management with jaw physiotherapy; eventually she could not open her mouth despite the absence of joint involvement. Re-exploration along with formal jaw physiotherapy was achieved and optimal jaw opening was maintained. Myofibromas are rare benign desmoid tumors that can present anywhere in the body in solitary and multicentric forms, and previously did not present significant challenges to surgical and medical management. Tumors of the mandible may present with trismus and soft tissue ankylosis, which can mimic temporomandibular joint dysfunction in the absence of joint involvement. Physical therapy, rehabilitation, and soft tissue contracture release are key to management and improving outcomes in oral cancer patients, regardless of tumor pathology.

Oral myofibroma presenting as an aggressive gingival lesion

Myofibromas are benign neoplasms of myofibroblastic origin and rarely encountered in the oral cavity. Myofibroma may frequently grow rapidly leading to suspicion of malignancy. This may lead to a tendency for aggressive management. The histopathology of this tumour has similarity with other spindle cell tumours and often requires immunohistochemical staining for diagnosis. Here, we present a case of myofibroma in a 15-year-old female patient who reported with an aggressive gingival swelling and discuss the various histopathological differential diagnosis.

[Isolated neurofibroma of the tongue]

A clinical case of successful treatment of isolated tongue neurofibroma presented patient K., 64 years old, referred to the clinic complaining of a feeling of «discomfort» on swallowing. With a comprehensive examination, a diagnosis of an isolated tongue neurofibroma was established. Surgical treatment was performed. The diagnosis was confirmed morphologically. The presented clinical case of isolated tongue neurofibroma in an elderly patient is casuistic in nature, of scientific and practical interest due to the rarity and unusualness of the disease.

Immunohistochemistry: An indispensable aid in diagnosis and management of infantile myofibroblastoma

Myofibroma is a benign tumor of myofibroblasts occurring commonly in infants and children. It can occur as a solitary lesion or as multiple lesions in the soft tissues or intraosseously. The presence of the solitary lesion is common in the soft tissues of the head-and-neck region but rare in jawbones. Histologically, it has a biphasic pattern of presentation and mimics spindle cell tumors. Immunohistochemistry is essential for its confirmatory diagnosis. This article describes a case of this rare lesion presenting as a solitary lesion in the left body of the mandible in a 7-month-old boy baby. The diagnostic and therapeutic challenges have been discussed.

Benign connective and soft-tissue neoplasms of the oral and maxillofacial region: Cross-sectional study of 1066 histopathological specimens

BACKGROUND

Benign connective and soft-tissue neoplasms (CSTNs) are unusual in the head and neck region. The aim of the present study was to evaluate the demographic and clinicopathological features of these neoplasms.

METHODS

A cross-sectional study was conducted of cases diagnosed as benign CSTNs, with data collected from biopsy records. The chi-square test was used. A p-value <0.05 was considered indicative of statistical significance.

RESULTS

Among the 38 119 specimens, 1066 (2.79%) were benign CSTNs: 369 fibroblastic/myofibroblastic, 250 adipocytic, 179 vascular, 130 neural, 94 osseous/cartilaginous, 19 muscular, and two fibrohistiocytic. Most patients were female (62.8%) and white-skinned (45.8%). Mean age was 42 years. The tongue (25.2%) was the most affected site for extraosseous neoplasms.

CONCLUSION

This study had the largest sample of benign oral and maxillofacial CSTNs. Although these tumors have similar clinical features, the characterization and differentiation detailed here may help clinicians with regards to the correct diagnosis.

Aggressive Intraosseous Myofibroma of the Maxilla: Report of a Rare Case and Literature Review

Myofibroma (MF) is a benign mesenchymal myofibroblast-derived tumor, which occurs most frequently in children, and rarely affects the maxilla. We reported a case of an aggressive intraosseous lesion found in the maxilla of a 9-year-old female child. Intraorally, the swelling extended from tooth 12 to 16, causing displacement of teeth 13, 14, and 15. Computed tomography revealed a large osteolytic lesion causing thinning and cortical erosion. Microscopically, the lesion showed a proliferation of spindle-shaped cells, with elongated nuclei and eosinophilic cytoplasm, arranged in interlaced fascicles. The immunohistochemical analysis revealed cytoplasmic positivity for α-SMA and HHF-35, and negativity for desmin, laminin, S-100, β-catenin, and CD34. Ki-67 was positive in 8% of tumor cells. The diagnosis was MF. Herein, we describe an additional case of central MF arising in the maxilla, including clinical, imaging, microscopical, and immunohistochemical features, as well as a review of the literature.

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.

Infantile myofibromatosis treated by mandibulectomy and staged reconstruction with submental flap and free fibula flap: a case report

BACKGROUND

Infantile myofibromatosis is the most common benign fibrous tumor in infants. Three different types have been reported in the literature. The most commonly affected areas are the head, the neck and the trunk. Our patient showed a very high level of mandibular destruction resistant to all mandibular sparing treatment strategies requiring segmental mandibulectomy and complex reconstruction.

CASE PRESENTATION

We describe a rare case of multicentric infantile myofibromatosis with mandibular bone destruction. The treatment required a succession of chemotherapy, a subtotal transoral resection and a hemi-mandibulectomy. The mandibular reconstruction was staged with initial bridging titanium plate with a submental flap, followed later by a fibula free flap.

CONCLUSION

Mandibular involvement by myofibromatosis is rare, and the extend of bone destruction and reconstruction make this case unique. To our knowledge, this is the only reported case of fibula free flap mandibular reconstruction in a patient with infantile myofibromatosis , as well as one of the youngest reported submental island flaps for any pathology. We describe the clinical presentation and management, including relevant imaging, histopathology, medical and surgical treatment as well as a review of relevant literature.

Myofibroblastic lesions in the oral cavity: Immunohistochemical and ultrastructural analysis

OBJECTIVE

To immunohistochemically characterize a group of oral myofibroblastic lesions (MLs) and to evaluate the ultrastructural features of myofibroblasts.

MATERIAL AND METHODS

Using a tissue microarray technique (TMA), cases of myofibroma (MF), of nodular fasciitis (NF), of desmoplastic fibroma (DF), and of myofibroblastic sarcoma (MS) from the Universidad Autónoma Metropolitana Xochimilco, and a Private Oral Pathology Service in Mexico City were stained with antibodies against alpha-smooth muscle actin (α-SMA), H-caldesmon, vimentin, desmin, β-catenin, CD34, anaplastic lymphoma protein kinase (ALK-1), and Ki-67.

RESULTS

Nineteen of the 22 MF cases, 2/5 of the NF cases, 1/10 of the DF cases, and 1/2 of the MS cases were positive for α-SMA. 1/2 of the MS cases were positive for desmin; 6/10 of the DF cases were positive for β-catenin, and 2 of the MF cases were positive for ALK-1. All of the MLs were positive for vimentin and negative for H-caldesmon and CD-34. The Ki-67 labeling index in all of the 8/22 MF, 3/5 NF, and 2/2 MS cases was ≥10%. For all of the MLs evaluated, ultrastructural analysis revealed spindle-shaped cells containing endoplasmic reticulum and peripheral actin filament bundles.

CONCLUSION

In certain myofibroblastic lesions, the use of auxiliary techniques (such as immunohistochemistry) can be critical for differential diagnosis.

Solitary myofibroma of the lumbar vertebra in young adult: A case report with 4-year follow-up of postoperative CT or MRI

BACKGROUND

Solitary myofibroma of the spine is extremely rare, particularly among adults. To the best of our knowledge, only 3 cases affecting lumbar vertebrae have been reported in the English language literature. Of them, only 1 case was an adult case of solitary myofibroma affecting the L1 vertebra.

METHODS

We report a case of solitary myofibroma affecting the L5 vertebra in an 18-year-old man and the postoperative imaging of solitary myofibroma for the first time. Conventional radiographs demonstrated an expansile osteolytic lesion with thinned cortex and marginal sclerosis. Computed tomography (CT) showed a purely osteolytic expansile lesion with partial disappearance of thinned cortex. MRI of the lesion revealed an isointense signal on T1-weighted images, an inhomogeneous slightly hyperintense signal on T2-weighed images, and homogeneous avid enhancement with gadolinium.

RESULTS

Surgical excision was performed and the lesion was diagnosed as solitary myofibroma on pathological examination. One-year follow-up postoperative CT demonstrated decreased size of the osteolytic lesion with sclerotic change. Four-year follow-up postoperative MRI revealed complete resolution of the lesion replaced by normal fatty marrow.

CONCLUSION

If a benign-looking expansile osteolytic lesion reveals a homogeneously isointense signal on T1-weighted image, inhomogeneous slightly hyperintense signal on T2-weighted image, and homogeneous avid enhancement with gadolinium, solitary myofibroma should be considered in the differential diagnosis of spine bone tumors. It can be resolved completely.

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.

Pseudomyogenic Hemangioendothelioma: A Vascular Tumor Previously Undescribed in the Oral Cavity

The pseudomyogenic hemangioendothelioma (PMH) is a low-grade malignant vascular neoplasm of different tissue planes including skin and soft tissue. Primary tumors in the skeletal muscle and bone have also been diagnosed. The PMH was introduced into the WHO classification of tumors of soft tissue and bone in 2013. This is the first description of oral involvement. A 21-year-old female presented with a 2-month old swelling of her gingiva. The swelling appeared red in color and was soft in consistency. A clinical diagnosis of a pyogenic granuloma was made and an incisional biopsy was submitted for histopathological evaluation. The lesion consisted of a proliferation of spindle and epithelioid looking cells. Cells were arranged in loose fascicles and sheets. Rhabdomyoblast-like cells were also seen. No mitotic figures were present. Lesional cells were reactive to cytokeratin AE1/AE3 and CD31. Lesional cell reactivity to S100 protein, HMB 45, SMA, Desmin and CD34 was negative. Following the diagnosis, a wide excision for clear margins was performed. No recurrence has been reported 2 years since the removal. The PMH is a cutaneous tumor that behaves in an indolent fashion. This is the first report of oral involvement by this neoplasm. Recognition of its histopathological features and immunohistochemical reactivity will prevent misadventures in the diagnosis of oral lesions.

Central myofibroma of the maxilla

Myofibroma is a rare benign localized or generalized proliferation of myofibroblastic tissue occurring mostly in infants or children. In the oral region, most lesions occur in the mandible, lip, buccal mucosa, and tongue; however, the lesions arising in the maxilla are very rare. Myofibroma has an aggressive clinical presentation and is often treated aggressively because of an inappropriate diagnosis. A unique feature of central myofibroma of the jaws is the potential for teeth and other odontogenic structures to be involved by tumor. We report a case of myofibroma arising in the left side of the maxilla of a 12-year-old girl and describe the differential diagnosis from other spindle cell lesions of neural and smooth muscle origin. We treated the case using surgical excision under general anesthesia. Immunohistochemical staining was done for establishing the diagnosis since histopathological diagnosis with conventional staining could not distinguish myofibroma from spindle cell tumors.

Nasal Cavity and Paranasal Sinuses

The nasal cavity and paranasal sinuses occupy the top of the upper respiratory tract and form pneumatic spaces connected with the atmosphere. They are located immediately beneath the base of the cranium, where crucial vital structures are harbored. From this region, very much exposed to airborne agents, arise some of the more complex and rare benign and malignant lesions seen in humans, whose difficulties in interpretation make this remarkable territory one of the most challenging in the practice of surgical pathology.

Contents of this chapter cover inflammations and infections, polyps and pseudotumors, fungal and midfacial destructive granulomatous lesions, as well as benign, borderline, and malignant neoplasms. Among the neoplasms, emphasis is made on those entities characteristic or even unique for the sinonasal region, such as Schneiderian papillomas, glomangiopericytoma, intestinal- and non-intestinal-type adenocarcinomas, olfactory neuroblastoma, nasal-type NK-/T-cell lymphoma, and teratocarcinosarcoma. Moreover, recently recognized entities involving this territory, i.e., HPV-related non-keratinizing carcinoma, NUT carcinoma, and SMARCB1-deficient basaloid carcinoma, are also discussed in the light of their specific molecular findings. Furthermore, the text is accompanied by numerous classical and recent references, several tables, and 100 illustrations.

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.

Solitary myofibroma of the mandible: an immunohistochemical and ultrastructural study with a review of the literature

A solitary myofibroma (MF) is an unusual spindle cell neoplasm that usually arises in the soft tissue, skin, or bone of the head and neck region in infancy. We report an extremely rare case of MF of the mandible in an 18-year-old Japanese woman together with the conventional histologic, immunohistochemical, and electron microscopic findings. The tumor was well circumscribed and composed of fibroblast-like or myofibroblast-like spindle cells. On immunohistochemical evaluation the tumor cells were positive for vimentin, α-smooth muscle actin, HHF-35, and calponin, but negative for neurogenic antigens and markers for vascular endothelial cells. The Ki-67 labeling index was 10 % and the p53 labeling index was 10 %. Ultrastructural examination revealed smooth muscle cell differentiation. The patient was treated by surgical resection and underwent follow-up without any signs of recurrence. MF presents a wide range of differential diagnosis, including benign and malignant neoplasms. Therefore, accurate diagnosis may avoid an unnecessarily aggressive therapy.

Solitary myofibroma of the mandible in an adult with magnetic resonance imaging and positron emission tomography findings: a case report

Myofibroma is a benign tumor composed of myoid spindle cells. The prevalence of myofibroma in the oral cavity is very low, with the mandible being the most common site. This report describes an adult case of myofibroma that arose on the mandible and includes magnetic resonance imaging (MRI) and positron emission tomography (PET) findings. On the MRI T1-weighted images, the tumor appeared with signal iso-intensity and was highly and heterogeneously enhanced with contrast material. On the T2-weighted images, it appeared with increased signal intensity. ¹⁸ F-fluorodeoxyglucose (FDG)-PET imaging showed abnormal strong accumulation of FDG in the left mandibular region. The tumor was removed by marginal resection of the left mandible under general anesthesia. Histopathological findings revealed that the tumor stroma contained abundant thin-walled vessels. The postoperative course was uneventful, and we found no evidence of recurrence at the postoperative 34-month follow-up.

Submandibular myofibroma: a case report

PURPOSE

Myofibroma is a rare benign spindle cell neoplasm, and the aim of the present study was to carry out a literature review and present a clinical case of a patient with a myofibroma in the submandibular region and its management.

CONCLUSIONS

Diagnosis of myofibroma can be reached by a histopathologic and immunohistochemical analysis and surgical excision is the treatment of choice.