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Scanning electron microscope and x-ray diffraction analysis assisting the diagnosis of a sialolith in the parotid duct

2011; Elsevier BV; Volume: 112; Issue: 3 Linguagem: Inglês

10.1016/j.tripleo.2011.03.020

1528-395X

Ana Carolina Prado Ribeiro, Adriele Ferreira Gouvêa, Márcio Ajudarte Lopes, Mário José Romañach, Pablo Agustín Vargas,

Oral and gingival health research

A 60-year-old man presented with a painless blackish well defined nodule in the parotid duct region of the left buccal mucosa. The nodule was ∼1.0 cm in diameter, freely movable, and present 2 months (Fig. 1). The medical history was noncontributory, and the main clinical diagnosis was of a foreign body. An excisional biopsy was performed under local anesthesia, and 3 blackened stone-like fragments associated with soft tissue were removed from the parotid duct and submitted to histopathologic examination. Macroscopic analyses of the surgical specimens showed 1 well defined black structure inside the soft tissue and 3 stone-like black fragments (Fig. 2). Microscopic analyses of the soft tissue fragment revealed a sialolith within the dilated excretory salivary duct, which presented squamous metaplasia (Fig. 3, A). The sialolith displayed a lamellated pattern of calcification with alternation between eosinophilic and basophilic zones disposed concentrically (Fig. 3, B). In an attempt to elucidate the nature of the black stone-like material, scanning electron microscopy (SEM; Jeol JSM-5600LV) and energy-dispersive x-ray analysis were performed. The SEM analysis of the external surface displayed a cobblestone aspect, sparse cellular elements, and organic membranous remains on the surface. Also, the longitudinal fracture surface of the black stone-like material showed parallel arrangement of the crystalline structures (Fig. 4, A). The energy-dispersive x-ray analysis detected large amounts of carbon (C), silicium (Si), calcium (Ca), phosphorus (P), and sodium (Na) on the rough external surface, with a predominance of C over the other elements (Fig. 4, B). The chemical components observed in microanalyses of the black stone-like material allowed the diagnosis of sialolith. At the time of writing, the patient had been under clinical follow-up for 12 months with no recurrences and no alteration of parotid gland function.Fig. 3A, Dilated excretory salivary duct presenting squamous metaplasia and containing a sialolith (hematoxylin-eosin [HE], ×25). B, Lamellated pattern of calcification with alternation between eosinophilic and basophilic zones disposed concentrically (HE, ×100).View Large Image Figure ViewerDownload Hi-res image Download (PPT)Fig. 4A, Scanning electron microscopy of the stone-like fragments. B, Energy-dispersive x-ray analysis: peaks of carbon.View Large Image Figure ViewerDownload Hi-res image Download (PPT) Sialoliths often develop in the ducts of the salivary glands, accounting for 30% of salivary diseases and most commonly involving the submandibular glands (83%-94%) and less frequently the parotid glands (4%-10%) and sublingual glands (1%-7%).1Riesco J.M. Juanes J.A. Díaz-González M.P. Blanco E.J. Riesco-López J.M. Vázquez R. et al.Crystalloid architecture of a sialolith in a minor salivary gland.J Oral Pathol Med. 1999; 28: 451-455Google Scholar, 2Torres-Lagares D. Barranco-Piedra S. Serrera-Figallo M.A. Hita-Iglesias P. Martínez-Sahuquillo-Márquez A. Gutiérrez-Pérez J.L. et al.Parotid sialolithiasis in Stensen's duct.Med Oral Patol Oral Cir Bucal. 2006; 11: E80-E84Google Scholar Many theories have been proposed to explain salivary calculi formation, including calcification around foreign bodies, desquamated epithelial cells, and microorganisms. In general, sialoliths are composed of an organic and an inorganic matrix presenting calcium phosphate as the major component; show a central core and a laminar peripheral structure.3Kasaboğlu O. Er N. Tümer C. Akkocaoğlu M. Micromorphology of sialoliths in submandibular salivary gland: a scanning electron microscope and x-ray diffraction analysis.J Oral Maxillofac Surg. 2004; 62: 1253-1258Google Scholar, 4Alcure M.L. Della Coletta R. Graner E. di Hipolito Jr, O. Lopes M.A. Sialolithiasis of minor salivary glands: a clinical and histopathological study.Gen Dent. 2005; 53: 278-281Google Scholar Sialolithiasis usually appear around the age of 40 years old, though it can also have an early onset in teenagers and can also affect older patients. Sialolithiasis has a predilection for male patients, particularly in cases of parotid gland.2Torres-Lagares D. Barranco-Piedra S. Serrera-Figallo M.A. Hita-Iglesias P. Martínez-Sahuquillo-Márquez A. Gutiérrez-Pérez J.L. et al.Parotid sialolithiasis in Stensen's duct.Med Oral Patol Oral Cir Bucal. 2006; 11: E80-E84Google Scholar In the parotid gland, salivary calculi usually occur unilaterally inside the duct, and their size is frequently <1 cm. The present case showed similar clinical features compared with previously reported cases: the patient was a 60-year-old man at the time of the diagnosis, presenting with a unilateral asymptomatic growth in the left parotid duct measuring ∼1 cm. Most patients present with a single stone. However, multiple stones occur in 32% of cases in the parotid gland and 22% in the submandibular gland.5Huang T.C. Dalton J.B. Monsour F.N. Savage N.W. Multiple, large sialoliths of the submandibular gland duct: a case report.Aust Dent J. 2009; 54: 61-65Google Scholar Ben Lagha et al.6Ben Lagha N. Alantar A. Samson J. Chapireau D. Maman L. Lithiasis of minor salivary glands: current data.Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2005; 100: 345-348Google Scholar evaluated 239 published cases of sialoliths of the minor salivary glands and found multiple sialoliths described in 3 cases. Liu et al.,7Liu D.G. Zhang Z.Y. Zhang Y. Zhang L. Yu G.Y. Diagnosis and management of sialolithiasis with a semirigid endoscope.Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2009; 108: 9-14Google Scholar evaluating a semirigid endoscopic technique for diagnosis and management of sialoliths in the Stensen's duct, encountered 6 out of 12 analyzed ducts presenting multiple sialoliths. In the present case, the patient presented 4 sialoliths in the Stensen's duct. Some different blackened foreign materials have been described in different sites of the oral mucosa,8Rocha A.C. Bernabé D.G. Amato-Filho G. Guimarães-Júnior J. Machado G.G. Foreign body in the hard palate of children and risk of misdiagnosis: report of 3 cases.J Oral Maxillofac Surg. 2009; 67: 899-902Google Scholar such as plastic fragments from a child's toy, artificial finger nail, and iron fragment,9Gouvêa A.F. Hanemann J.A.C. Pereira A.A.C. Ribeiro A.C.P. Romañach M.J. Jorge J. et al.Uncommon foreign body reactions occurring in the lip: clinical misdiagnosis and the use of special techniques of analysis.Head Neck Pathol. 2011; 5: 86-91Google Scholar but none inserted in the Stensen's duct. Moreover, the clinical and macroscopic appearance of the material (blackened multiple fragments) was very suggestive of foreign bodies, not sialoliths. Therefore, SEM and energy-dispersive x-ray analysis was used to determine the nature of the material. Riesco et al.1Riesco J.M. Juanes J.A. Díaz-González M.P. Blanco E.J. Riesco-López J.M. Vázquez R. et al.Crystalloid architecture of a sialolith in a minor salivary gland.J Oral Pathol Med. 1999; 28: 451-455Google Scholar and Kasaboğlu et al.3Kasaboğlu O. Er N. Tümer C. Akkocaoğlu M. Micromorphology of sialoliths in submandibular salivary gland: a scanning electron microscope and x-ray diffraction analysis.J Oral Maxillofac Surg. 2004; 62: 1253-1258Google Scholar investigated the structure of sialoliths and their apparent parallel arrangement of the crystalline structures to determine their microscopic morphology and chemical composition. They observed that salivary calculi are mainly composed of Ca, P, carbonate, and small amounts of Mg, potassium chloride, and ammonium. In the present case, SEM analysis showed parallel arrangement of the crystalline structures, and the energy-dispersive x-ray analysis of the crystalline structures detected varied amounts of C, Si, Ca, P, and Na with a predominance of C, leading to the diagnosis of sialolith. In conclusion, this case showed that SEM and energy-dispersive x-ray analysis are useful tools for diagnosis of some oral lesions with distinct presentation, and these special diagnosis techniques might be used to identify the origin of structures associated with the lesions. The authors gratefully acknowledge Adriano Luis Martins from the Department of Oral Diagnosis, Piracicaba Dental School—Unicamp, for his SEM examination.