Pathogenesis and Diverse Histologic Findings of Sialolithiasis in Minor Salivary Glands

Sialolithiasis of minor salivary gland: a challenging diagnostic dilemma

Minor salivary gland sialolithiasis (MSGS) is a not uncommon oral mucosal disease. Its clinical appearance may mimic a mucocyst or other benign submucosal overgrowth. Stasis of saliva, which accompanies MSGS, usually results in minor salivary gland inflammation, with a chronic sialadenitis appearance. MSGS typically is a painless lesion but can become painful when the salivary gland parenchyma or excretory duct becomes infected, with or without pus. However, misdiagnosis of this condition is rather common, as the clinical appearance is asymptomatic. The most common location is the upper lip, and MSGS affects males and females, with a slight predilection for males. The sialolith causing MSGS may be obvious during surgical excision, as in the case reported. In other cases, sialolith may be absent or fragmented. Differential diagnosis includes mucocele, swelling due to local irritation like fibroma and diapneusia, chronic abscess of the oral mucosa, and neoplasms either benign (lymphangioma, pleiomorphic adenoma) or malignant. Histopathological examination is needed to establish clinical diagnosis.

A case of minor salivary gland sialolithiasis of the upper lip

BACKGROUND

Sialolithiasis is the most common disease of the salivary glands. Sialolithiasis usually develops in the major salivary glands, and rarely in the minor salivary glands, with only 2% of all cases of sialolithiasis occurring in the minor salivary glands and sublingual glands. Sialoliths in the minor salivary glands result in few or no clinical symptoms and are seldom identified on imaging.

CASE PRESENTATION

We report herein our experience with a case of minor salivary gland sialolithiasis in a 67-year-old woman. On examination, an elastic soft, mobile, and well-circumscribed mass was palpable within the left upper lip. Ultrasound examination revealed a hypoechoic mass with heterogeneous internal echoes. The mass was excised under local anesthesia. Based on histopathological findings, a diagnosis of minor salivary gland sialolithiasis was established.

CONCLUSIONS

Diagnosis of minor salivary gland sialolithiasis is challenging due to the difficulty of detecting sialoliths on imaging. A well-circumscribed mass was detected in the upper lip, and ultrasound examination revealed a round lesion, raising the suspicion of a benign tumor. Other diseases that can develop at the upper lip are calcified lymph node, phlebolith, fibroma, pleomorphic adenoma, myxoma, vascular malformation, salivary gland tumor, non-specific sialadenitis, and malignant tumor. Surgical excision is the favored approach for confirming a diagnosis of intramucosal nodular lesions.

Sialolitíase em equino: relato de caso

RESUMO Sialolitíase é uma afecção que afeta as glândulas salivares ou seus ductos, caracterizada pela presença de estruturas calcificadas, denominadas de sialolitos, com crescimento lento e gradual, geralmente assintomático, dificultando ou impedindo o fluxo normal de saliva. Devido à ausência de relatos na literatura nacional, descreve-se o caso de uma égua de 15 anos, que apresentava um sialolito de 13cm no ducto parotídico havia mais de dois anos, próximo à crista facial. O diagnóstico foi realizado por meio do exame clínico: visualização do aumento de volume, palpação do sialolito, avaliação odontológica; e de exames complementares: radiografia e ultrassonografia. Optou-se pelo tratamento cirúrgico, através do acesso percutâneo, pois é o mais indicado para cálculos grandes, realizando-se sutura do ducto de Stenon, sem presença de fístulas no pós-operatório. Foi de extrema importância a avaliação e os cuidados odontológicos durante a realização do procedimento, pois as pontas dentárias facilitam a formação dos cálculos.

A Case of Sialolithiasis in a Minor Salivary Gland of the Buccal Mucosa

Sialolithiasis is a common disease of the major salivary glands. In contrast, Sialolithiasis of Minor Salivary Glands (SMSG) is very rare. Only 2% of all cases of sialolithiasis develop in minor salivary glands and sublingual glands. Furthermore, the clinical and imaging features of SMSG frequently differ from those encountered in major salivary glands thus, hindering proper clinical diagnosis of SMSG. Histologically, SMSG is characterized by ductal ectasia (sometimes with deep cystic dilatation), acinar atrophy and periductal inflammation. Herein, we describe a patient suffering from SMSG in the left buccal region. Based on the clinicopathological findings of this case and a review of the literature, we propose that this entity should be included in the differential diagnosis of intra-mucosal nodules.

A Solitary Phlebolith in the Buccal Mucosa: Report of a Rare Entity and Clinicopathologic Correlation

Pathological conditions can give rise to calcifications within oral mucosa representing either a local or systemic disturbance. Inflammation, trauma, debris acting as nidus and vascular lesions have been attributed as principal causes for occurrence of calcifications within the oral mucosa. Occurrence of multiple calcified thrombi (phleboliths) is considered pathognomonic for hemangiomas and vascular malformations in the oral and maxillofacial region. Isolated occurrence of phlebolith in oral mucosa though very rare, especially without any underlying vascular lesions, can be diagnostically challenging. Either a traumatic association at that site or a hemangioma of childhood that has regressed once the individual became an adult are the possible explanations suggested for the occurrence of these unique solitary phleboliths. Histologically, an "onion-ring"-like concentric lamellar fibrosis around a central core with varying amounts of calcifications and presence of minute vascular channels within or around calcified lamellae is characteristic for phlebolith. There is a high propensity for misdiagnosing solitary phlebolith located in sites like the buccal mucosa where various other pathologic soft-tissue calcifications, such as sialoliths, calcified lymph nodes, traumatic myositis ossificans, etc. can occur and they too appear radiopaque in radiographs. Besides, the absence of any associated underlying vascular lesion adds to the mispercep-tion. In such cases, histopathological examination with routine hematoxylin and eosin staining alone may not be sufficient to determine the accurate diagnosis. Allied clinical history and immunohistochemistry can aid to arrive at the final diagnosis. We report such a case of nonvascular lesion-associated solitary phlebolith in the right buccal mucosa of a healthy 49-year-old male patient and discuss its differential diagnosis with emphasis on histological presentation.

Sialolithiasis of minor salivary glands: A review of 17 cases

Background/purpose

To our knowledge, sialolithiasis in minor salivary glands is very rare, and information about the disease is limited. The current study aimed to provide updated data regarding the disease in Taiwan. The data were compared with those of previous case series studies.

Materials and methods

The features of 17 cases of histopathologically confirmed sialolithiasis in minor salivary glands between 1991 and 2015 in our institution were retrospectively analyzed.

Results

Most of the patients were male (n = 14; 82.35%), with only three female patients (17.65%). The mean age of the 17 patients was 62.93 years (range, 35–82 years). Fifteen cases (∼88%) were found within the 6^th–9^th decades. Seven cases (∼41%) were identified in patients aged ≥70 years, six of which had been diagnosed in the most recent 5 years (2011–2015). The most common site was the buccal mucosa (n = 7; 41.18%), followed by the upper lip (n = 5; 29.41%), lower lip (n = 3; 17.65%), and vestibule and retromolar area (each n = 1; 5.88%). Only one case (5.88%) was clinically diagnosed as sialolithiasis prior to biopsy examination.

Conclusion

The current study demonstrated an aging tendency and a male predilection of sialolithiasis in minor salivary glands in Taiwan when compared with published case series studies.

Vascular Calcification and Stone Disease: A New Look towards the Mechanism

Calcium phosphate (CaP) crystals are formed in pathological calcification as well as during stone formation. Although there are several theories as to how these crystals can develop through the combined interactions of biochemical and biophysical factors, the exact mechanism of such mineralization is largely unknown. Based on the published scientific literature, we found that common factors can link the initial stages of stone formation and calcification in anatomically distal tissues and organs. For example, changes to the spatiotemporal conditions of the fluid flow in tubular structures may provide initial condition(s) for CaP crystal generation needed for stone formation. Additionally, recent evidence has provided a meaningful association between the active participation of proteins and transcription factors found in the bone forming (ossification) mechanism that are also involved in the early stages of kidney stone formation and arterial calcification. Our review will focus on three topics of discussion (physiological influences-calcium and phosphate concentration-and similarities to ossification, or bone formation) that may elucidate some commonality in the mechanisms of stone formation and calcification, and pave the way towards opening new avenues for further research.

Structure and growth of sialoliths: computed microtomography and electron microscopy investigation of 30 specimens

Theories have been put forward on the etiology of sialoliths; however, a comprehensive understanding of their growth mechanisms is lacking. In an attempt to fill this gap, the current study has evaluated the internal architecture and growth patterns of a set of 30 independent specimens of sialoliths characterized at different scales by computed microtomography and electron microscopy. Tomography reconstructions showed cores in most of the sialoliths. The cores were surrounded by concentric or irregular patterns with variable degrees of mineralization. Regardless of the patterns, at finer scales the sialoliths consisted of banded and globular structures. The distribution of precipitates in the banded structures is compatible with a Liesegang-Ostwald phenomenon. On the other hand, the globular structures appear to arise from surface tension effects and to develop self-similar features as a result of a viscous fingering process. Electron diffraction patterns demonstrated that Ca- and P-based electrolytes crystallize in a structure close to that of hydroxyapatite. The organic matter contained sulfur with apparent origin from sulfated components of secretory material. These results cast new light on the mechanisms involved in the formation of sialoliths.

Intraoral approach for removal of large sialolith in submandibular gland

Sialolithiasis is a benign pathology that occurs most frequently in the submandibular salivary gland due to its anatomic features. Depending on the size and degree of calcification, a sialolith can be visible in radiographic examinations. Patients commonly experience pain and/or edema when the ducts are obstructed. The authors report two cases of sialolithiasis of the submandibular gland after searching for the source of swelling in the submandibular region. The diagnosis was confirmed by clinical and tomographic examinations. Despite the considerable size of the sialoliths, treatment consisted of the removal of the calcified mass using an intraoral surgical approach. The prognosis is often good and there is generally no recurrence of the condition.

Proteomic and scanning electron microscopic analysis of submandibular sialoliths

OBJECTIVES

Several theories have been proposed regarding the genesis of sialoliths, including the organic core theory, which suggests epithelial or bacterial etiology originating in the central core. Our aim was to use novel methodologies to analyze central areas (the core) of calculi from sialolithiasis patients.

MATERIALS AND METHODS

The structures of the halves of six submandibular salivary stones were analyzed by scanning electron microscopy (SEM). After structural analysis, from the other six halves, samples from the central parts of the core and peripheral parts of the core were digested with trypsin and analyzed by matrix-assisted laser desorption ionization-time of flight mass spectrometry. The peptide mass fingerprints were compared with the results of in silico digestion.

RESULTS

SEM analysis of the sialoliths showed that organic structures (collagen/fibrous-like structures, bacterial fragments) were visible only outside of the core in the concentric layers of external areas, but not in the core area. The mass spectrometry (MS)/MS post-source decay experiments were completed from the four, most intense signals observed in the MS spectrum and human defensin was proven to be present in three of the examined samples, originated from the peripheral region of three cores.

CONCLUSIONS

Although proteomic analysis demonstrated defensin protein in the peripheral region of the core in three sialoliths, SEM failed to prove organic structures in the core.

CLINICAL RELEVANCE

New investigation modalities still cannot prove organic structures in the core, henceforward challenging the organic core theory.

Intra-oral surgical access for the treatment of bilateral submandibular sialolithiasis: case report

Sialolithiasis is a disease that affects the salivary glands. It is characterized by the presence of calcified structures within the duct system or within the glandular parenchyma. Those calculi, or sialoliths, can obstruct normal salivary flow, potentially leading to infectious sialadenitis, with pain, local swelling, and purulent discharge. Treatment typically consists of the surgical removal of the calculus, often in conjunction with sialoadenectomy. The authors report an atypical case of bilateral submandibular gland sialolithiasis treated conservatively, using intra-oral access to remove the calculi.