The juxtaoral organ-a pitfall for pathologists

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.

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

Prognostic value of frozen section in t1, t2 carcinoma of oral cavity

Complex anatomy of oral cavity makes it difficult for a surgeon to assess margins of oral cancer accurately and positive margins compromise loco regional disease control, thus surgeon may rely on frozen section assessment for marginal status. We discussed the prognostic value of frozen section in early carcinoma of oral cavity. 90 patients with pT1 and pT2 oral cavity cancer operated from January 2010 to December 2011 under single consultant surgeon were retrospectively evaluated. Log rank test and multivariate cox regression model was used for testing frozen section against the survival and recurrence free status. Survival of patients with positive or negative frozen section was significant (p = 0.037), Survival of patients with positive or negative histology report was significant (p = 0.004), however; prognosis of patients with positive margins despite revision under frozen control was poorer to the patients with negative margin. Frozen section assessment is accurate but their use in the surgery of oral cavity cancer might not improve loco regional disease control or survival when used routinely.

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.

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.

Solid glomus tumor of the pterygoid fossa: a lesion mimicking an epithelial neoplasm of low-grade malignancy

An example of a solid glomus tumor occurring in the pterygoid fossa is described. Despite its epithelial appearance on light microscopy, the tumor was of connective tissue origin. The diagnosis of glomus tumor was based on characteristic cytologic, ultrastructural, and immunohistochemical features, but the unusual site of the tumor made the diagnosis difficult.