Head and Neck Pathology

BACKGROUND: Granular Cell Odontogenic Fibroma (GCOF) is a rare odontogenic neoplasm reported over time with different names. The purpose of this study is to review all available data on the GCOF in the scientific literature, with a summary of all reported cases and a report of a new case. METHODS: This review was conducted following the PRISMA guidelines. An electronic search was performed up to November 2022. RESULTS: Thirty-nine studies reporting fifty-three cases were included...

BACKGROUND: Adenoid ameloblastoma (AdAM) is a frequently recurrent tumor that shows hybrid histological features of both ameloblastoma and adenomatoid odontogenic tumor (AOT). AdAM is expected to be classified as a new subtype of ameloblastoma in the next revision of the World Health Organization (WHO) odontogenic tumor classification. However, whether AdAM is a histologic variant of ameloblastoma or AOT remains unclear. To establish a new category, genetic evidence indicating the tumor category is necessary...

BACKGROUND: Intraoral minor salivary gland tumors are relatively rare lesions with histological subtypes not commonly found in major salivary glands. This study aimed to retrospectively evaluate the clinicopathologic features of intraoral minor salivary gland tumors from the Tokyo Dental College Hospital, Japan, and compare them with findings from other epidemiological studies. METHODS: We conducted a retrospective clinicopathologic evaluation of 432 cases of intraoral minor salivary gland tumors [161 male (37...

BACKGROUND: Mycobacterial spindle cell pseudotumor (MSCP) represents an uncommon tumor-like proliferation associated with nontuberculous mycobacterial infection, i.e., M. avium intracellulare, affecting primarily the lymph nodes of immunocompromised men in their 5th decade. Involvement of the nasal cavity by MSCP is exceedingly rare with only 3 well-documented examples in the literature. METHODS: A 74-year-old, HIV-negative, man presented with a 0.5-cm nodule of the left nasal cavity clinically presenting as a "nasal polyp...

BACKGROUND: Lymphadenomas are rare benign tumors of the major salivary glands that are further classified as sebaceous and non-sebaceous. No association with viruses has been reported so far. Little is known about the mechanisms that allow lymphadenomas to undergo malignant transformation. Among these rare instances, there has never been a malignant transformation to Epstein-Barr virus (EBV)-associated lymphoepithelial carcinoma. METHODS: Clinical data of the reported case were retrieved from the patient's electronic medical record...

BACKGROUND: Mucoepidermoid carcinoma is a malignant salivary gland tumor which, in most cases, is composed of variable proportions of mucous, epidermoid, and intermediate cells. METHODS: We report a case of parapharyngeal mucoepidermoid carcinoma with highly unusual ("monomorphic") light microscopic features as well as atypical immunohistochemical properties. Molecular analysis was performed using the TruSight RNA fusion panel. RESULTS: The tumor featured heretofore undescribed histopathological features: sheets and nests composed of monomorphic neoplastic (plump spindle to epithelioid) cells with no mucous, intermediate, glandular/columnar, or any other cell type identified...

BACKGROUND: Odontogenic carcinosarcoma (OCS) is an exceptionally rare malignant mixed odontogenic neoplasm, which mostly arises from recurrent benign odontogenic tumour that undergoes malignant transformation. METHODS: A literature review was conducted using the keyword of "Odontogenic carcinosarcoma" and all relevant articles were screened. The data collected include demographic profile (age, gender), clinical information (symptoms, location, size), radiologic features, histopathological examination, management, recurrence, metastases, and survival status...

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BACKGROUND: Ossifying fibroma (OF) of the craniofacial skeleton is a fibro-osseous lesion characterized by various patterns of bone formation in a cellular fibroblastic stroma. The molecular landscape of OF remains mostly unknown. There are a few known pathogenic abnormalities in OF, including HRPT2 mutations in conventional OF and SATB2 translocations in juvenile psammomatoid OF. On the other hand, conflicting reports exist regarding MDM2 gene amplification and chromosomal copy number alterations (CNA) in OF...

BACKGROUND: Ectomesenchymomas (EMs) are extremely rare neoplasms composed of malignant mesenchymal components and neuroectodermal derivatives. They are described in a wide variety of locations, with the head and neck region being one of the most frequently involved areas. EMs are usually managed as high-risk rhabdomyosarcomas and have similar outcomes. METHODS: We present the case of a 15-year-old female with an EM that arose in the parapharyngeal space and extended into the intracranial space...

BACKGROUND: This systematic review aimed to conduct a complete investigation of the demographic aspects, clinicopathological features, degrees of epithelial dysplasia, and malignant transformation rate of actinic cheilitis. METHODS: The study was performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and registered in the International Prospective Register of Systematic Reviews (CRD42020201254). A search without year and language restrictions was performed using PubMed/MEDLINE, Embase, Virtual Health Library, Scopus, Web of Science, and gray literature...

BACKGROUND: The spectrum of neuroendocrine neoplasia (NEN) of the head and neck region is wide-ranging and diverse, including a variety of diagnoses stretching from benign and low-malignant tumor forms to highly proliferative, poor prognosis neuroendocrine carcinoma (NEC). Moreover, there are several non-neuroendocrine differential diagnoses to keep in mind as well, displaying various degree of morphological and/or immunohistochemical overlap with bona fide neuroendocrine lesions. METHODS: Review...

BACKGROUND: Nested is defined as "cellular clusters arranged in small groupings with intervening vascular or stromal networks, lacking lumens or glandular formation." Using this definition, multiple neoplastic and non-neoplastic lesions of the head and neck come into the differential. We have broadly organized the differential diagnosis of "nested" tumors into entities with neuroendocrine differentiation, squamous differentiation, thyroid follicular cell differentiation, and other lesions...

BACKGROUND: Oral ulcers represent a full thickness loss of the mucosal epithelium leading to exposure of the submucosal connective tissue. These are common and usually self-limited lesions, although they may sometimes result from neoplasms, most commonly squamous cell carcinoma. Lymphoproliferative disorders may be difficult to diagnose in apthous ulcers since they mimic reactive inflammation. METHODS: This review presents ten rare oral lymphoid proliferations which should not be missed when assessing oral ulcer biopsies...

BACKGROUND: Spindled lesions are a challenging area in head and neck pathology. This is particularly true in the sinonasal tract, where several uncommon entities with both unique and overlapping morphologic, immunophenotypic, and/or molecular features can occur. METHODS: Review. RESULTS: The clinicopathologic characteristics of biphenotypic sinonasal sarcoma and nine important differential diagnostic considerations with one or more overlapping feature are summarized to establish a practical framework for approaching spindled lesions of the sinonasal tract...

BACKGROUND: Desmoplastic melanoma is a rare subtype of melanoma mainly appearing on sun-exposed skin. Clinically, it is many times non-pigmented and therefore the diagnosis is often not suspected. METHODS: Review article. RESULTS: In this paper we review the main histopathological, immunohistochemical, and molecular features of desmoplastic melanoma, as well as the top 10 morphologic differential diagnoses which should be considered in most cases...

BACKGROUND: Cystic lesions of the gnathic bones present challenges in differential diagnosis. This category includes a smorgasbord of odontogenic and non-odontogenic entities that may be reactive or neoplastic in nature. While most cystic jaw lesions are benign, variability in biologic behavior makes distinction between these entities absolutely crucial. METHODS: Review. RESULTS: Two clinical cases are presented in parallel and are followed by an illustrated discussion of the ten most likely differential diagnoses that should be considered when confronted with a cystic jaw lesion...

BACKGROUND: Oncocytes are a component of many metaplastic and neoplastic lesions throughout the head and neck area, primarily originating in salivary/seromucinous glands and the thyroid gland. In addition, other lesions can contain cells that mimic oncocytes (pseudo-oncocytes); these can be of epithelial or non-epithelial origin. METHODS: Review article. RESULTS: Oncocytic metaplasia is common in seromucinous glands throughout the upper aerodigestive tract, most notable in the oral cavity, nasopharynx and larynx...

BACKGROUND: Optically clear cytoplasm may occur in neoplastic and non-neoplastic conditions, either as a characteristic feature of a disease entity or as a morphologic rarity, potentially creating diagnostic dilemmas in various organ systems. In the head and neck, clear cell change can occur in lesions of salivary, odontogenic, thyroid, parathyroid, or sinonasal/skull base origin, as well as in metastases to these regions. METHODS: This review elaborates the top ten clear cell lesions in the head and neck, emphasizing their distinguishing histologic, immunohistochemical, and molecular attributes, and presents a rational approach to arriving at an accurate classification...

BACKGROUND: Myoepithelial neoplasms of the salivary gland are benign or malignant neoplasms composed exclusively of neoplastic myoepithelial cells. These tumors, including the benign myoepithelioma and the malignant counterpart myoepithelial carcinoma, exhibit a wide range of cytomorphologic features and architectural patterns. METHODS: Review. RESULTS: Myoepithelial cells can be epithelial, plasmacytoid, clear cell, spindle cell, and/or oncocytic cell, arranging as trabeculae, solid sheets, nests, cords, and/or single cells...