A case of nodular hyperplasia of the juxtaoral organ in man

The juxta-oral organ of Chievitz (organum yuxtaorale) updated: Embryology, anatomy, function and pathology

BACKGROUND

The Chievitz's organ or juxta-oral organ is a mysterious bilateral structure, phylogenetically preserved, which develops from the mouth epithelium as an invagination that loses connection to it in the prenatal period. It is located laterally to the walls of the oral cavity in an imprecise anatomical location and receives abundant innervation from the buccal nerve. Structurally it consists of non-keratinizing squamous-like neuroepithelial cells surrounded by two layers of connective tissue with nerve fibers and different morphotypes of sensory corpuscles. Its function is completely unknown although based on its rich innervation it is assumed that works as a mechanoreceptor.

METHODS

We have performed immunohistochemistry for axonal and Schwann cells, and the putative mechanoproteins ASIC2, TRPV4 and Piezo2 in sections of fetal juxta-oral organ.

RESULTS

Intraparenchymatous nerve fibers and sensory corpuscles were observed as well as immunoreactivity for Piezo2 in both nerve fibers and epithelial parenchymatous cells.

CONCLUSIONS

We add indirect evidence that the juxtaoral organ is a mechanoreceptor because in addition to its dense innervation, the epithelial cells and sensory nerve fibers display immunoreactivity for the mechanogated ion channel Piezo2. Based on current knowledge, the functional and clinical importance of the juxta-oral organ should be further investigated.

Neuroepithelial Structures of the Oral Soft Tissues Including the Juxtaoral Organ of Chievitz: A Literature Review and Audit of Diagnosed Cases

The juxtaoral organ of Chievitz (JOOC) is a part of microanatomy composed of bland epithelial islands closely associated with small nerves and usually described within the soft tissue on the lingual aspect of the posterior mandible. Similar structures are documented in the posterior tongue. There is a risk of misinterpretation as carcinoma showing perineural invasion. An audit was undertaken of diagnosed cases of the JOOC and similar neuroepithelial structures identified within the oral soft tissues of surgical specimens. Nineteen cases were identified. Epithelial islands ranged < 0.5-4 mm in maximum dimension and lay in close association with small nerves. Epithelial cells showed a squamoid appearance but were without keratinisation. There was no atypia and mitotic figures were not seen. In 53% of cases the epithelial cells showed cytoplasmic clearing, in 26% of cases there was brown pigment and in 11% of cases there were calcifications. In 53% of cases, these neuroepithelial structures lay within the soft tissue lingual to the mandible in the retromolar area, 26% of the structures were placed buccal to the mandible, 11% of the structures lay adjacent to the maxillary tuberosity and 11% of the structures were within the posterior tongue.

Juxtaoral Organ of Chievitz, an Obscure Anatomical Structure Masquerading as Perineural Invasion of Mucoepidermoid Carcinoma

The juxtaoral organ was first described by Chievitz in 1885. This is typically located deep to the medial pterygoid muscle (unilaterally or bilaterally) in the pterygomandibular space. Juxtaoral organ of Chievitz (JOOC) is usually incidentally detected in biopsies or resection specimen of other tumors but exceptionally, it can present as mass lesions. Awareness of this normal anatomic structure is important, because the epithelial islands in this area could be misinterpreted as an invasive carcinoma, mucoepidermoid carcinoma, an odontogenic tumor such as ameloblastoma or adenomatoid odontogenic tumor, or a perineural invasion by carcinoma. When a portion of the juxtaoral organ of Chievitz is accidentally exposed by frozen biopsy, there is an even higher risk of mistaking these cells for an invasive cancer or a perineural invasion of carcinoma. We report this to create awareness about this obscure structure and to draw attention to its differential diagnosis

Organogenesis of the juxta-oral organ in mice

The juxta-oral organ is a bilateral organ in the mammalian bucca. It consists of epithelial cords with surrounding mesenchyme. It develops from embryonic oral epithelium, but its macroscopic morphology in mice is less studied and seems to be very different from that of humans. The juxta-oral organ in mice extends more widely from the subcutaneous tissue of the mandible near the lateral fascia of the masseter to the submucosa of the soft palate. In this paper, we report that the mutant mouse allele Bmp7(lacZ) presented intense lacZ expression in the epithelial component of the juxta-oral organ in its homo- and heterozygous states. The main aims of this study were to show that this mutant mouse allele is suitable for observing macroscopic structure of the juxta-oral organ and to describe the development of this organ during embryonic and postnatal stages. Whole-mount beta-gal staining of this strain of mouse showed that the juxta-oral organ in mice appeared at E12.0 from oral epithelium and lost connection with it before E12.5. Then, the juxta-oral organ extended anteriorly to the lateral fascia of the masseter and posteriorly to the submucosal layer of the soft palate via the orbit. The mature juxta-oral organ had no connection to other epithelia such as those of the bucca and parotid duct. It persisted until adulthood and there seemed to be no tendency to regress. Transmission electron microscopy showed that each part of the juxta-oral organ was an epithelial cord surrounded by a basement membrane and mesenchymal tissue.

Morphogenesis of the juxtaoral organ in humans

The juxtaoral organ was studied using light microscopy in 55 human embryos and 90 fetuses at different stages of development. The juxtaoral organ arises from the epithelium at the bottom of the transverse opening of the primitive mouth during O'Rahilly stage 16 and becomes detached from the epithelium after O'Rahilly stage 18. The juxtaoral organ is innervated by the buccal nerve from O'Rahilly stage 20 onward, and its connective tissue capsule is clearly visible after week 11 of development. This study enabled us to describe three main periods of juxtaoral organ development: (1) the period of epithelial condensation and invagination, at O'Rahilly stages 16-17; (2) the period during which the juxtaoral organ becomes detached from the oral epithelium and is innervated, at O'Rahilly stages 18-23; and (3) the period during which the connective tissue capsule is formed, after week 11 of development. We also analysed the juxtaoral organ of five additional fetuses by immunohistochemistry with anti-NF-200 to verify their innervation. The results show that the juxtaoral organ may have a function in the mechanical activity of the region.

Juxtaoral organ of Chievitz presenting clinically as a tumour

An extremely rare hamartomatous lesion of the juxtaoral organ of Chievitz (JOOC) in a 63 year old man is reported. The tumour appeared as a large mass in the infratemporal fossa with associated mandibular bone resorption; histologically, it was well encapsulated and composed of numerous tangled masses of benign squamous epithelial nests and mature fibrofatty tissue. There were no histological features suggestive of neoplastic transformation. A literature survey confirmed that this is the first adult case of JOOC presenting clinically as an extraoral tumour.

Tumour of the juxtaoral organ

The juxtaoral organ is a normal and constant structure of the oral cavity. It consists of benign epithelial nests. We describe an intraoral tumour of the juxtaoral organ in a child. The tumour was not diagnosed after clinical and radiological examinations because it is extremely rare. A histological examination revealed a tumour of the juxtaoral organ, presumed to be neuroid hamartoma. This is only the second time that a tumour of the juxtaoral organ has been described in a child. We also describe the location, the embryology, the histology and the function of this organ. This is important because this structure can be confused with carcinomas of the oral cavity when examining frozen sections.

Intraoral tumor of Chievitz in a child

Juxtaoral organs known as organs of Chievitz are intramuscular embryonic structures found close to the angle of the mandible near the insertion of the pterygomandibular raphae. They are considered of neuroepithelial origin with no known function. We describe the first tumor of the organ of Chievitz which presented intraorally in a child. Immunohistochemically, the Chievitz nests showed positive reaction for vimentin, cytokeratins, and epithelial membrane antigen and ultrastructurally demonstrated cytoplasmic processes and intermediate filament bundles. These observations, together with light microscopic features, suggest that the epithelial nests of the organ of Chievitz are meningothelial rather than neuroepithelial.

Neuroepithelial hamartoma of the oral cavity

We report a previously undescribed gingival lesion composed of squamous epithelial islands in close association with bundles of nonmyelinated nerves. A review of the pertinent literature is presented and the histologic differential diagnosis is discussed. We suggest the term neuroepithelial hamartoma for this lesion.

A microscopic focus of traumatic neuroma with intralesional glandular structures: an incidental finding

A 50-year-old man received radiation therapy and chemotherapy for squamous cell carcinoma of the right floor of the mouth. Histologic examinations of surgical materials revealed the presence of benign ductal epithelial structures containing mucinous material within a small traumatic neuroma of the mandibular alveolar mucosa. Presumably, the residual salivary ducts of the sublingual glands may become incorporated during the development of a traumatic neuroma secondary to the destruction of tissue. Our search of the literature has failed to reveal a similar recorded occurrence.

The juxtaoral organ-a pitfall for pathologists

The first well-documented case in which the juxtaoral organ was identified in a surgical specimen removed because of oral cancer is reported. Recognition of this normal structure, the histological picture of which considerably resembles that of a mucoepidermoid carcinoma was crucial in determining the precise extent of the malignant process. Misinterpreting the JOO as cancer may lead to false prognoses or to unnecessarily extensive surgery. The differential diagnostic importance of orofacial epithelial structures localised perineurally is discussed.