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

Sinonasal Specific Bone Lesions, Including Fibro-Osseous and Select Odontogenic Lesions

Sinonasal bone lesions encompass a diverse spectrum, ranging from nonneoplastic and benign conditions to aggressive, malignant neoplasms. These lesions can affect individuals across various age groups, from pediatric to adult patients. Recognizing these entities is crucial, given the variability in treatment approaches, recurrence rates, and prognoses. This review explores the common and uncommon but distinctive bone lesions affecting the sinonasal region, highlighting key clinical, radiographic, morphologic, and genetic features for each. Additionally, we provide helpful tips on distinguishing and accurately classifying each lesion within its relevant differential diagnoses.

Infantile Sinonasal Tract Myxomas with Orbital Involvement: Presentation of Two Cases and Comprehensive Literature Review

Objective: Our aim is to present two cases of infantile sinonasal tract myxoma with orbital involvement and conduct a comprehensive literature review of the topic. We aim to provide a summary of the presentation of infantile sinonasal tract myxomas to effectively aid clinicians in considering this rare entity as a potential diagnosis. Methods: We present a case series and a retrospective review of the published literature in the English language. A search was conducted between 1945 and 2023 on sinonasal myxoma. Cases of infantile (<3 years) sinonasal myxoma in the literature were reported as well as two cases of our own. Data was collected from each of the identified articles on the age of presentation, sex, initial presentation, tumor location, imaging, pathology, and treatment. Results: Forty-eight cases of sinonasal myxoma in children <3 years of age were identified. These cases had a slight male preponderance (F:M, 1:1.39) and an average age of diagnosis of sixteen months. Of the cases included, the majority involved the maxilla and maxillary sinuses (83.3%) and commonly presented with a painless slow-growing mass in the region of the tumor. Characteristic CT findings are homogenous solid masses with heterogeneous contrast enhancement. On MRI, these lesions appear hypointense on T1 with highly variable contrast enhancement and hyperintense on T2. Conclusions: We present two cases of infantile sinonasal myxoma with secondary orbital involvement followed by a major review. Treatment of these cases with surgical excision (confirmed clear margins) provided 0% rates of recurrence in the reported cases. Due to the rarity of these tumors and recent histological reclassification, a comprehensive review of this condition will assist clinicians in their management of it.

Mesenchymal Tumors of the Head and Neck

The majority of neoplasms of the head and neck are of epithelial origin primarily including mucosal squamous cell neoplasms (papillomas; squamous cell carcinoma) as well as salivary gland neoplasms. However, the full spectrum of mesenchymal neoplasms (benign and malignant) typically arising in soft tissue sites may also develop in superficial layers of the upper aerodigestive tract. The diversity of mesenchymal neoplasms arising in the head and neck is beyond the scope of this article, and our focus will be on some of the more common and/or diagnostic problematic mesenchymal tumors occurring in the sinonasal tract, oral cavity/odontogenic, pharynx, larynx, and neck.

Odontogenic Myxomas Harbor Recurrent Copy Number Alterations and a Distinct Methylation Signature

Odontogenic myxoma is a rare, benign, and locally aggressive tumor that develops in the tooth-bearing areas of the jaw. The molecular mechanisms underlying odontogenic myxomas are unknown and no diagnostic markers are available to date. The aim of this study was to analyze DNA methylation and copy number variations in odontogenic myxomas to identify new molecular signatures for diagnostic decision-making. We collected a cohort of 16 odontogenic myxomas from 2006 to 2021 located in the mandible (n = 10) and maxilla (n = 6) with available formalin-fixed paraffin-embedded or fresh frozen tumor tissue from a biopsy or resection material. Genome-wide DNA methylation and copy number variation data were generated from 12 odontogenic myxomas using the Illumina Infinium Methylation EPIC array, interrogating >850,000 CpG sites. Unsupervised clustering and dimensionality reduction (Uniform Manifold Approximation and Projection) revealed that odontogenic myxomas formed a distinct DNA methylation class. Copy number profiling showed recurrent whole-chromosome gains (trisomies) of chromosomes 5, 8, and 20 in all cases, and of chromosomes 10, 12, and 17 in all except one case. In conclusion, odontogenic myxomas harbor recurrent copy number patterns and a distinct DNA methylation profile, which can be used as an additional diagnostic tool in the appropriate clinical and radiologic context. Further research is needed to explain the genetic mechanisms caused by these alterations that drive these locally aggressive neoplasms.

Different Shades of Desmoid-Type Fibromatosis (DTF): Detection of Noval Mutations in the Clinicopathologic Analysis of 32 Cases

BACKGROUND

Desmoid-type fibromatosis (DTF) is a locally aggressive myofibroblastic/fibroblastic neoplasm with a high risk of local recurrence. It has a variety of histologic features that might confuse diagnosis, especially when detected during core needle biopsy. The Wnt/β-catenin pathway is strongly linked to the pathogenesis of DT fibromatosis.

METHOD

This study examined 33 desmoid-type fibromatoses (DTFs) from 32 patients, analyzing its clinical characteristics, histologic patterns, occurrence rates, relationship with clinical outcomes, immunohistochemical and molecular findings.

RESULTS

The DTFs exhibit a range of 1 to 7 histologic patterns per tumor, including conventional, hypercellular, myxoid, hyalinized/hypocellular, staghorn/hemangiopericytomatous blood vessels pattern, nodular fasciitis-like, and keloid-like morphology. No substantial association was found between the existence of different histologic patterns and the clinical outcome. All thirty-three (100%) samples of DTF had a variable percentage of cells that were nuclear positive for β-catenin. An NGS analysis detected novel non-CTNNB1 mutations in two DTFs, including BCL10, MPL, and RBM10 gene mutations.

CONCLUSIONS

This study reveals a diverse morphology of DTFs that could result in misdiagnosis. Therefore, surgical pathologists must comprehend this thoroughly. Also, the importance of the newly identified non-CTNNB1 gene mutations is still unclear. More research and analyses are needed to completely grasp the clinical implications of these mutations.

Spindle Cell Tumors of the Sinonasal Tract: A Diagnostic Update with Focus on Ancillary Workup

Spindle cell neoplasms arising in the head and neck may be challenging to recognize due to their relative rarity. While underlying molecular alterations are increasingly elucidated, testing for these features may not be readily available. In most cases, combinations of key morphologic features and diagnostic immunohistochemical markers can be used to replace molecular diagnostics. Conversely, some molecular alterations and expression of their surrogate biomarkers are not specific for any one entity, and it is important to recognize these to avoid diagnostic pitfalls. In this review, we discuss both old and new spindle cell tumors of the sinonasal tract, with an emphasis on histologic features and clinically relevant immunohistochemical markers serving as surrogate markers for underlying genomic alterations.