Primary ameloblastoma of the sinonasal tract: a clinicopathologic study of 24 cases

Maxillary Ameloblastoma in an Asiatic Black Bear (Ursus thibetanus)

An approximately 30-year-old intact female Asiatic black bear (Ursus thibetanus) was presented for annual examination and a history of ptyalism. A large 9.5 cm × 5 cm × 5 cm, firm, round mass was identified attached to the hard palate on physical examination. A computed tomography scan was performed, and the heterogeneous, mineral-attenuating mass was seen arising from the right aspect of the palatine bone and extending rostrally to the level of the last maxillary molars, caudally into the oropharynx, and dorsally into the nasal choana. Surgical debulking was performed to remove the portion of the mass within the oral cavity. Histopathologic analysis was consistent with a keratinizing ameloblastoma. Nine months postoperatively, the patient was asymptomatic for the tumor. The patient was euthanized 23-months postoperatively, and severe diffuse pustular dermatitis, growth of the ameloblastoma on the hard palate, and various degenerative and aging changes were noted on necropsy at that time. This is the first report of an ameloblastoma in a member of the Ursidae family.

Ameloblastoma of the Mandible in a 16-Year-Old Female-Case Report

Ameloblastoma is a benign epithelial tumor that has aggressive, destructive and unlimited growth potential, having the capacity for recurrence and malignant transformation. Regarding the symptoms and clinical signs, the presentation of ameloblastoma is poor. In children and young people, ameloblastoma can be difficult to diagnose, because it mimics other benign lesions. Its diagnosis requires a combination of imaging data, histopathological analysis and molecular tests. The methods of treatment consist of radical surgery (segmental resection) and conservative treatments (enucleation with bone curettage). The particularity of the presented case is represented by the late request for medical consultation, a direct consequence of the measures implemented to prevent and control the spread of COVID-19.

Malignant and Nonmalignant Sinonasal Tumors

Sinonasal tumors are rare, diverse, complex lesions with overlapping demographic and clinical features. Malignant tumors are more common, with a grave prognosis, and require biopsy for accurate diagnosis. This article briefly reviews the classification of sinonasal tumors and provides imaging examples and imaging characteristics of each clinically important nasal and paranasal mass lesions. Although there are no true pathognomonic imaging features, it is important for the radiologist to have a broad knowledge of the various CT and MR imaging findings that can help narrow the differential diagnosis and aid in early diagnosis and mapping of tumor for treatment planning.

Endoscopic Management of Recurrent Maxillary Sinus Ameloblastoma in a Child With Autism Spectrum Disorder: A Case Report

Ameloblastomas are slow-growing, aggressive odontogenic epithelial tumors that originate from the jawbone. One of the most easily relapsing maxillofacial tumors, ameloblastomas mainly occur in the mandibular molar area and ascending branch, although they can occasionally occur in the nasal cavity and paranasal sinuses. A 14-year-old child with autism spectrum disorder underwent sinus computed tomography (CT) under anesthesia. A swollen tumor had grown in the left maxillary sinus, and the bone of the maxillary sinus was damaged. Nine months after the first operation, recurrence was observed in the left maxillary sinus. The pathological diagnosis was ameloblastoma. Due to the child's inability to communicate and cooperate with the treatment normally, he underwent endoscopic surgery again combined with low-temperature plasma treatment. No tumor recurrence was found on reexamination 6 months after surgery.

Update from the 5th Edition of the World Health Organization Classification of Head and Neck Tumors: Nasal Cavity, Paranasal Sinuses and Skull Base

The World Health Organization Classification of Head and Neck Tumours recently published the 5th edition. There are new entities, emerging entities, and significant updates to the taxonomy and characterization of tumor and tumor-like lesions, specifically in this article as it relates to nasal cavity, paranasal sinuses and skull base. Importantly, the number of diagnostic entries has been reduced by creating category-specific chapters for soft tissue, hematolymphoid, melanocytic, neuroectodermal, and metastatic tumors. Bone and salivary gland tumors are also not separately reported in the sinonasal tract, but included in the jaw and salivary gland sections, respectively. Repetition of characteristic entities in each anatomic site was also reduced, instead highlighting only the unique features in each anatomic site. Two new entities (SWI/SNF complex-deficient sinonasal carcinomas and HPV-related multiphenotypic sinonasal carcinoma) will be highlighted in this review, with a discussion of several emerging entities. There is a short description of updated information for all 24 diagnostic entities included in this edition to allow the reader a snapshot of current state of knowledge, but to encourage more investigation and further broaden understanding of these diverse and rare entities.

Maxillary Ameloblastoma: A Review With Clinical, Histological and Prognostic Data of a Rare Tumor

Diagnosis of odontogenic tumors can be challenging due to their rarity and diverse morphology, but when arising near the tooth, the diagnosis could be suspected. When their location is not typical, like inside the paranasal sinuses, the diagnosis is less easy. Maxillary ameloblastomas are exceedingly rare with only sparse information on their epidemiological, histological and genetic characteristics. The aim of this report is to thoroughly review the available literature in order to present the characteristics of this tumor. According to available data, maxillary ameloblastomas can occur in all ages but later than mandible ones, and everywhere within the maxillary region without necessarily having direct contact with the teeth. No sex preference has been shown. The most common histological patterns seen in this location are the follicular and plexiform ones. Maxillary ameloblastomas are locally aggressive neoplasms, thus therapy aims for excision including normal bone beyond the lesion. In contrast to mandible ameloblastomas, maxillary ones most commonly show mutations of the SMO gene. Furthermore, differential tumor diagnosis is thoroughly discussed in the present review.

Rare Diseases of the Nose, the Paranasal Sinuses, and the Anterior Skull Base

Due to their low incidence and thus resulting limited diagnostic criteria as well as therapeutic options, rare diseases of the nose, the paranasal sinuses, and the anterior skull base are a significant challenge. The value as of which a disease has to be considered as rare amounts to a maximum of 5 patients per 10 000 people. Within these diseases, however, there are extreme differences. Some rare or orphan diseases like for example the inverted papilloma belong to regularly diagnosed and treated diseases of larger departments of oto-rhino-laryngology whereas other rare diseases and malformations have only been described in less than 100 case reports worldwide. This fact emphasizes the necessity of bundling the available experience of diagnostics and therapy. The present article gives an overview about rare diseases of the nose, the paranasal sinuses, and the anterior skull base from the field of diseases/syndromes of the olfactory system, malformations of the nose and paranasal sinuses, ventilation and functional disorders as well as benign and malignant tumors. The classification and data on diagnostic and therapeutic options were established based on the current literature.

Dentigerous cyst exhibiting prominent mucous cell metaplasia: report of a unique case mimicking central mucoepidermoid carcinoma

A Japanese male aged 61 presented with persistent pain in the left posterior area of the mandible for several weeks. A panoramic X-ray revealed a unilocular lesion showing characteristics of a dentigerous cyst associated with an impacted third molar. A cystectomy was performed and histopathological examination revealed a cystic lesion with a fibrous wall. The lumen was covered with non-keratinizing squamous cells with obvious intercellular bridges, which were intermingled with partially ciliated goblet-cell-type mucous and columnar cells. Such cystic lesions should be carefully examined to distinguish them from the glandular odontogenic cyst and central mucoepidermoid carcinoma of the jawbone.

Maxillary Sinus Ameloblastoma: Transnasal Endoscopic Management

Ameloblastoma (AM) is a slow growing and aggressive benign tumor with an odontogenic epithelial origin arising from the mandible or maxilla. The odontogenic neoplasm invades local tissues asymptomatically and accounts for 1% of oral tumors and over 10% of odontogenic tumors. A 64-year-old man with a history of allergic fungal rhinosinusitis (AFRS) undergoing a revision image-guided endoscopic sinus surgery was found to have a fibrous mass suspicious of malignancy projecting inferolaterally and attached to the floor of the left maxillary sinus. Diagnostic biopsies were taken, and additional surgery was required to successfully resect the tumor via a transnasal endoscopic dissection. Multiple permanent pathology samples concluded the diagnosis of an AM. Endoscopic investigations led to the incidental discovery and ultimate complete endoscopic resection of the AM. The utilization of an endoscopic resection compared to the traditional maxillectomy with reconstruction results in significant less short and long-term morbidity for the patient.

Synchronous occurrence of odontogenic keratocyst and ameloblastoma: A case report and review of the literature

Odontogenic keratocyst (OKC) and ameloblastomas are distinct histopathologically diagnosed odontogenic lesions of the oral cavity. Both are primarily located in the posterior regions of the mandible, however, they can involve the maxilla as well. The occurrence of both an OKC and ameloblastoma in a patient is very uncommon. This case demonstrated such a lesion in the mandible of a 57 years old female. The diagnostic work-up and features of both lesions are illustrated with special focus on histopathological variances distinguishing OKC from ameloblastoma with the support of immunohistochemistry. This case highlights the importance of identifying accurate diagnoses for such lesions which may prompt clinical implications. Clinico-pathologic understanding of both lesions signifies the need for careful management plan and prevention of recurrence. Previously reported simultaneous occurrences of odontogenic cysts and/or tumors in the oral cavity are also reviewed.

Sinonasal Ameloblastoma

Ameloblastomas are benign but aggressive odontogenic tumors that most commonly affect the posterior mandible. Approximately 15% occur in the maxilla, with a subset thought to originate from the epithelial lining of the sinonasal cavities. Histologically, sinonasal ameloblastomas are identical to those of the oral cavity, with classical features of palisaded columnar basilar cells surrounding a central proliferation that resembles the stellate reticulum of a developing tooth. Unlike the gnathic variant, sinonasal ameloblastomas tend to affect males more than females, and the incidence of diagnosis peaks at a later age, approximately 60 years old. The overall prognosis is favorable, with local recurrence being the most common long-term sequalae.

Endoscopic Management of Benign Sinonasal Tumors: A Decade of Experience

Background

A variety of benign tumors present in the nasal and paranasal sinuses.

Methods

We review our experience over the last 10 years with endoscopic management of these tumors and discuss presentation, diagnostic considerations, and therapeutic options.

Results

Eighteen patients with benign sinonasal tumors were managed with endoscopic techniques. Representative cases are presented, including pleomorphic adenoma, ameloblastoma, meningioma, cholersterol granuloma, ossifying fibroma, fibrous dysplasia, and osteomas. Three patients (16.7%) required one revision endoscopic sinus procedure. Average follow-up was 4 years.

Conclusions

With the treatment of more complex cases being undertaken endoscopically, the need for individual therapeutic consideration and close follow-up is stressed. The combination of removal of benign tumors endoscopically and endoscopic surveillance in the outpatient setting has allowed a less radical surgical approach while resulting in decreased morbidity and better tumor control.

Odontogenic Cysts and Tumors

This article presents various odontogenic cysts and tumors, including periapical cysts, dentigerous cysts, odontogenic keratocysts, orthokeratinized odontogenic cysts, lateral periodontal cysts, glandular odontogenic cysts, ameloblastomas, clear cell odontogenic carcinomas, adenomatoid odontogenic tumors, calcifying epithelial odontogenic tumors, squamous odontogenic tumors, ameloblastic fibromas, ameloblastic fibro-odontomas, odontomas, calcifying cystic odontogenic tumors, and odontogenic myxomas. The authors provide an overview of these cysts and tumors, with microsopic features, gross features, differential diagnosis, prognosis, and potential diagnostic pitfalls.

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.

Odontogenic tumors, WHO 2005: where do we go from here?

As our knowledge of disease improves, its classification continually evolves. The last WHO classification of odontogenic tumors was 9 years ago and it is time for revision. We offer the following critique as a constructive, thought provoking challenge to those chosen to provide contemporary insight into the next WHO classification of odontogenic cysts, tumors, and allied conditions.

[Maxillary ameloblastoma extending into the sinonasal tract]

Maxillary ameloblastomas can extensively expand into the paranasal sinuses or even the nasal cavity due to a slow growth pattern. Sinusitis is rarely the first tumor-related complaint. Due to the various growth forms of ameloblastomas the challenging histological differential diagnosis includes several other odontogenic as well as benign and malignant non-odontogenic tumors, e.g. tumors from the mucosa of the paranasal sinuses, salivary glands and Rathke's pouch. Despite the radical surgical approach a complete resection with wide margins cannot always be achieved. Maxillary ameloblastomas show the highest recurrence rates.

[Primary plexiform ameloblastoma in the sinonasal tract of a 49-year-old female patient. Case report]

Sinonasal ameloblastoma is a rare tumor, which most frequently affects male patients in the 6th-7th decade. We report on the case of 49-year-old female patient presenting with nasal obstruction. Computed tomography revealed a solid and hypodense mass filling the maxillary sinus and the nasal cavity. The histological examination showed a plexiform ameloblastoma without significant bone erosion. Viewing this together with the literature review, we suggest that sinonasal ameloblastoma in female patients becomes apparent approximately one decade earlier than in male patients. This tumor should be considered in the differential diagnosis of unilateral sinonasal symptoms.

Ameloblastoma of the nasal septum origin: a case report

Background. Ameloblastoma is the most common odontogenic tumor. It represents about 1% of all tumors of the jaw. Extragnathic location of the ameloblastoma is typical and extremely rare. Case Report. We report a case of ameloblastoma of the nasal septum origin, causing nasal obstruction. According to our information, this is the first reported case of ameloblastoma coming from the nasal septum as a primary tumor without maxillary sinus involvement. Conclusions. Ameloblastoma can not only locate in the maxilla and mandible, but also in other regions of the craniofacial. Ameloblastoma should be considered in the differential diagnosis of tumors causing nasal obstruction. Nonspecific clinical features of sinonasal ameloblastoma make it extremely important to perform accurate diagnostic imaging and histopathological examination.

Ameloblastoma of the sinonasal tract: report of a case with clinicopathologic considerations

Ameloblastomas are locally aggressive jaw tumours with a high propensity for recurrence and are believed to arise from remnants of dental lamina or odontogenic epithelium. Extragnathic ameloblastomas are unusual, and primary sinonasal tract origin is very uncommon with few cases reported in the literature. We herein report a case of primary sinonasal ameloblastoma presented in a 74-year-old male with nasal obstruction, rhinorrhoea, and sinusitis. Nasal endoscopy showed the right nasal cavity completely obstructed by a polypoid lesion attached to the lateral nasal wall. A preoperative CT scan was performed showing a solid lesion, measuring 2 cm in the maximum diameter, extending from the nasopharynx area with obstruction of the ostiomeatal unit and sphenoethmoidal recess into the lateral pharyngeal space, laterally to the parotid, without continuity with maxillary alveola and antrum. The tumour was completely excised endoscopically, and a final diagnosis of ameloblastoma was rendered. At the 12-month followup, there was no evidence of recurrence.

Ameloblastoma: a rare nasal polyp

Ameloblastomas are locally aggressive jaw tumours with a high propensity for recurrence and are believed to be derived from remnants of odontogenic epithelium which does not undergo transformation to the point of enamel formation. Extragnathic ameloblastomas are unusual and primary nasal origin is extraordinarily uncommon.

Infrasellar craniopharyngiomas: case report and review of the literature

Although craniopharyngiomas account for a large percentage of pediatric intracranial tumors, there is a bimodal age distribution. Most of these neoplasms are suprasellar or sellar in location. In this report we describe an unusual case of an infrasellar craniopharyngioma in a child. Only four previous cases of infrasellar craniopharyngiomas with no sellar involvement have been described. Infrasellar craniopharyngiomas are part of the continuum representing intracranial craniopharyngiomas and ameloblastomas of the jaw. A transnasal endoscopic biopsy was performed with a preliminary diagnosis of craniopharyngioma. The patient then underwent a radical resection of the infrasellar tumor via a subfrontal transbasal approach. This case illustrates a rare and unusual location for a craniopharyngioma. Craniopharyngiomas should be considered in the differential diagnosis of infrasellar neoplasms. Infrasellar craniopharyngiomas compromise part of the spectrum of tumors originating from enamel-forming neural crest cells.

Ameloblastic carcinoma

Ameloblastic carcinoma (AC) is a rare aggressive malignant epithelial odontogenic tumor of the maxillofacial skeleton with a distinct predilection in the mandible. It may appear de novo or originate from a pre-existing ameloblastoma or odontogenic cyst. It exhibits cytological features of ameloblastoma and carcinoma. It may present as a cystic lesion with benign clinical features or as a large tissue mass with ulceration, significant bone resorption and tooth mobility. The clinical course of ameloblastic carcinoma is typically aggressive, with extensive local destruction. Direct extension of the tumour, lymph node involvement and metastasis to various sites has been reported. Wide local excision is the treatment of choice. Regional lymph node dissection should be considered and performed selectively. Radiotherapy and chemotherapy have limited role in the treatment of ameloblastic carcinomas. Close periodic reassessment of the patient is mandatory.

Ameloblastoma of the frontal sinuses: a rare site for recurrence

Ameloblastoma is a benign odontogenic tumour which commonly recurs after initial surgery; most recurrences occur at the site of the primary tumour. A rare case of recurrence of a maxillary ameloblastoma in the frontal sinuses is presented. To our knowledge there are no previous reports in the literature of a benign maxillary ameloblastoma extending into the frontal sinuses.

Ameloblastoma of the Sinonasal Tract: A Case Report

Ameloblastomas are locally aggressive gnathic tumors with a high propensity for recurrence. Presentation of an ameloblastoma exclusively in the sinonasal tract is extremely rare, with few reported cases in the literature. Management involves surgical excision and close follow-up. We report a case in which the patient had complete unilateral nasal obstruction caused by an ameloblastoma. The tumor was completely excised endoscopically, and at the 12-month follow-up, there was no evidence of recurrence.

Epizootic Ameloblastomas in Chinook Salmon (Oncorhynchus tshawytscha) of the Northwestern United States

Abnormal growths were observed on the lips and in the oral cavities of 2- and 3-year-old Chinook salmon (Oncorhynchus tshawytscha) maintained in one freshwater and one saltwater captive fish-rearing facility in the Columbia River (Pacific Northwest). Initially presenting as bilaterally symmetrical, red, irregular plaques on oral mucosal surfaces, the lesions developed progressively into large, disfiguring masses. Of the 502 natural parr collected for captive broodstock, 432 (86%) displayed these tumors, whereas cohort salmon (i.e., same year classes) in these same facilities remained unaffected. Morphologically similar neoplasms were collected occasionally from adult Chinook salmon that had returned to their natal streams. Histologic features of the tumors suggested that they were derived from the portion of dental lamina destined to form tooth root sulci; therefore, these neoplasms were diagnosed as ameloblastomas. The lesions also resembled archived specimens of Chinook salmon oral tumors, which had been described decades earlier. Etiologic investigations performed during the current outbreak included bacteriologic, virologic, genetic, ultrastructural analyses, and cohabitation exposure studies. Results of these efforts did not indicate an obvious genetic basis for this syndrome, attempts to isolate potentially causative viruses or bacteria were negative, and disease transmission to naïve fish was unsuccessful. A few intracytoplasmic hexagonal structures, possibly consistent with viral particles (∼100 nm), were observed ultrastructurally in a tumor cell from 1 of 6 specimens submitted for transmission electron microscopy. Although the presence of these particles does not constitute sufficient evidence for causality, an infectious or multifactorial etiology seems plausible.

Ameloblastic carcinoma arising from anterior skull base

Ameloblastic carcinoma (AC) is an aggressive malignant epithelial odontogenic tumor. It may appear de novo or originate from a pre-existing ameloblastoma or odontogenic cyst. To our knowledge, an AC that originates from the anterior skull base has not been reported before in the English literature. We report a case of an AC that originated from the anterior skull base and invaded the dura of the anterior fossa and discuss its clinical course and treatment.

Primary extracranial meningioma of the sinonasal tract

Meningiomas occurring outside the cerebrospinal axis can be primary at an extracranial site (nasal cavity, paranasal sinuses, and nasopharynx) or secondary extending from an intracranial lesion. Magnetic resonance imaging findings of an 8-year-old child with primary meningioma before and after surgery have been reviewed and compared to computed tomography and histological evaluation. The child had difficulty breathing through the left nostril and tearing of the left eye. After physical and radiological examination, a tumor comprising the left lower, middle turbinate, and ethmoidal cells was found and radically extirpated. On histological examination, the tumor was identified as meningothelial meningioma. On the basis of the clinical, radiological, and histological features, the tumor was diagnosed as extracranial meningioma of the sinonasal tract. A follow-up examination 6 months later revealed no evidence of recurrence of the tumor.

Ameloblastin gene (AMBN) mutations associated with epithelial odontogenic tumors

Ameloblastin (AMBN, MIM *601259) gene expresses an important protein (AMBN), present in the organic matrix of enamel. The AMBN protein has an important role in the differentiation of ameloblast cells and epithelium-mesenchyme signaling during odontogenesis which prompted us to investigate this gene in aggressive epithelial odontogenic tumors, such as ameloblastomas, and in some non-aggressive ones, such as the adenomatoid odontogenic tumor and the squamous odontogenic tumor. Six cases of epithelial odontogenic tumors were studied and normal cells of the patient's mucosa were used as negative controls. The results demonstrated novel mutations in all tumors, while mucosal cells showed the wild type DNA sequence. Our data demonstrates that AMBN gene has an important role in the tumorigenesis of subtypes of epithelial odontogenic tumors and that this phenotypic heterogeneity could be caused by genetic heterogeneity.

Odontogenic cysts, odontogenic tumors, fibroosseous, and giant cell lesions of the jaws

Odontogenic cysts that can be problematic because of recurrence and/or aggressive growth include odontogenic keratocyst (OKC), calcifying odontogenic cyst, and the recently described glandular odontogenic cyst. The OKC has significant growth capacity and recurrence potential and is occasionally indicative of the nevoid basal cell carcinoma syndrome. There is also an orthokeratinized variant, the orthokeratinized odontogenic cyst, which is less aggressive and is not syndrome associated. Ghost cell keratinization, which typifies the calcifying odontogenic cyst, can be seen in solid lesions that have now been designated odontogenic ghost cell tumor. The glandular odontogenic cyst contains mucous cells and ductlike structures that may mimic central mucoepidermoid carcinoma. Several odontogenic tumors may provide diagnostic challenges, particularly the cystic ameloblastoma. Identification of this frequently underdiagnosed cystic tumor often comes after one or more recurrences and a destructive course. Other difficult lesions include malignant ameloblastomas, calcifying epithelial odontogenic tumor, squamous odontogenic tumor, and clear-cell odontogenic tumor. Histologic identification of myxofibrous lesions of the jaws (odontogenic myxoma, odontogenic fibroma, desmoplastic fibroma) is necessary to avoid the diagnostic pitfall of overdiagnosis of similar-appearing follicular sacs and dental pulps. Fibroosseous lesions of the jaws show considerable microscopic overlap and include fibrous dysplasia, ossifying fibroma, periapical cementoosseous dysplasia, and low-grade chronic osteomyelitis. The term fibrous dysplasia is probably overused in general practice and should be reserved for the rare lesion that presents as a large, expansile, diffuse opacity of children and young adults. The need to use clinicopathologic correlation in assessing these lesions is of particular importance. Central giant cell granuloma is a relatively common jaw lesion of young adults that has an unpredictable behavior. Microscopic diagnosis is relatively straightforward; however, this lesion continues to be somewhat controversial because of its disputed classification (reactive versus neoplastic) and because of its management (surgical versus. medical). Its relationship to giant cell tumor of long bone remains undetermined.

Factors in the pathogenesis of tumors of the sphenoid and maxillary sinuses: a comparative study

OBJECTIVES/HYPOTHESIS

To explain the processes that lead to the development of tumors in the maxillary and sphenoid sinuses.

STUDY DESIGN

A 32-year review of the world's literature on neoplasms of these two sinuses and a randomized case-controlled study comparing the normal mucosal architecture of the maxillary to the sphenoid sinus.

METHODS

Analysis of a 32-year world literature review reporting series of cases of maxillary and sphenoid sinus tumors. Tumors were classified by histological type and separated into subgroups if an individual incidence rate was reported. Histomorphometry of normal maxillary and sphenoid sinus mucosa was performed in 14 randomly selected patients (10 sphenoid and 4 maxillary specimens). Specimens were fixed in 10% formalin, embedded in paraffin, and stained with periodic acid-Schiff (PAS) and hematoxylin. Histomorphometric analysis was performed with a Zeiss Axioscope light microscope (Carl Zeiss Inc., Thornwood, NY) mounted with a Hamamatsu (Hamamatsu Photonics, Tokyo, Japan) color-chilled 3 charge coupled device digital camera. The images were captured on a 17-inch Sony (Sony Corp., Tokyo, Japan) multiscan monitor and analyzed with a Samba 4000 Image Analysis Program (Samba Corp., Los Angeles, CA). Five random areas were selected from strips of epithelium removed from each sinus, and goblet and basal cell measurements were made at magnifications x 100 and x 400.

RESULTS

The literature review revealed that the number and variety of tumors in the maxillary sinus are much greater than those in the sphenoid. The incidence of metastatic lesions to each sinus is approximately equal. No recognized pattern of spread from any particular organ system could be determined. On histomorphometric study there were no statistically significant differences between the sinuses in the concentration of goblet cells, basal cells, or seromucinous glands.

CONCLUSIONS

Factors involved in the pathogenesis of tumors of the maxillary and sphenoid sinuses include differences in nasal physiology, embryology, morphology, and topography. There are no significant histological differences in the epithelium and submucous glands between the two sinuses to explain the dissimilar formation of neoplasms.

Sinonasal imaging: malignant disease

The clinical presentation of sinonasal malignancy overlaps that of more common benign inflammatory disease. For this reason, unsuspected malignant lesions are often first recognized on the screening CT exam. We will focus on the initial CT appearance of various malignancies and discuss the goals of imaging including the use of MR.