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Bilateral myoepithelioma of the nasopharynx: A case report
Auris Nasus Larynx 36 (2009) 496–500 www.elsevier.com/locate/anl
Bilateral myoepithelioma of the nasopharynx: A case report Elena Gaio a,*, Antonio Perasole b, Francesco Bagatella a a
Department of Otolaryngology-Head and Neck Surgery, City Hospital, Castelfranco Veneto, Italy b Department of Pathology, City Hospital, Castelfranco Veneto, Italy Received 18 March 2008; accepted 28 October 2008 Available online 30 December 2008
Abstract Myoepithelioma is a rare salivary tumour which is usually encountered in the parotid gland. Outside the parotid, myoepithelioma may arise from minor salivary glands of the hard palate and less frequently in bronchi or breast. In this report we describe the unique case of a metachronous bilateral nasopharyngeal myoepithelioma arising from the tubaric regions. Its microscopic features, immunophenotype, and the differential diagnosis together with a review of literature are discussed. # 2008 Elsevier Ireland Ltd. All rights reserved. Keywords: Nasopharynx; Myoepithelioma; Minor salivary gland
1. Introduction Neoplasms of minor salivary gland origin are rare in the sinonasal tract; in 1986 Spiro [1] revised 2807 consecutive cases of salivary neoplasm: 150 were localized in paranasal sinuses, only 9 (0.3%) arose in the nasopharynx [2]. The majority of cases of sinonasal salivary neoplasms usually are represented by pleomorphic adenomas [3]. Myoepitheliomas are rare tumours which are best defined in the major salivary glands, although they have been reported also in breast and lungs [4]. They account for less than 1% of all salivary neoplasms; the parotid gland and the minor glands of the hard palate are the most common sites of occurrence [5,6]. Their constituting element derives from myoepithelial cells that surround the salivary acina and intercalated ducts, exhibiting immunohistochemical and ultrastructural features of both epithelial and smooth-muscle cells [7]. Neoplastic myoepithelial cells may have different morphologies (epithelioid, spindle, plasmacytoid, and clear cell), and only occasionally they can have a biphasic pattern [8]. The considerable overlap in the histologic appearances * Corresponding author. Present address: via Madonna dei Prati 27 bis, 36040 Brendola (VI), Italy. Tel.: +39 0338 3090070; fax: +39 0444 401728. E-mail address: [email protected] (E. Gaio).
of pleomorphic adenomas and myoepitheliomas has lead many investigators to think that these tumours lie on a morphologic continuum [5,9] spanning from myoepithelioma (composed only by myoepithelial cells) to canalicular adenoma (composed only by epithelial duct cells). At the midpoint lie pleomorphic adenomas, constituted by proliferated myoepithelial cells and epithelial duct elements in variable proportion, embedded in a myxochondroid stroma of myoepithelial derivation. The close relationship between myoepithelioma and pleomorphic adenoma has also been investigated through cytogenetic studies: myoepitheliomas share the chromosome 12q alteration reported in a subset of pleomorphic adenomas [10]. The characteristic plasticity of myoepithelial cells, the resultant broad morphologic spectrum of myoepithelial tumours and the potential of myoepithelioma to originate outside major salivary glands account for the difficulties often experienced in its correct diagnosis.
2. Case report A 47-year-old woman presented to our Department in January 1998 with a 3-month history of left nasal obstruction and aural fullness. Three times earlier (in 1991, 1992 and 1994) she had already undergone in another hospital surgical
0385-8146/$ – see front matter # 2008 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.anl.2008.10.007
E. Gaio et al. / Auris Nasus Larynx 36 (2009) 496–500
497
excision of a left nasopharyngeal mass which was diagnosed as myoepithelioma. Unfortunately we could not access any information about her previous surgical treatments. On otolaryngological examination, the patient presented a large exophytic tumour growing from the left posterolateral nasopharyngeal wall occupying the homolateral half of the nasopharynx. The remainder of otolaryngological examination showed a retracted left tympanic membrane with limpid transudate behind it. A pure-tone audiometry revealed a left conductive hearing loss; the tympanogram showed a Jerger B-type curve in the left ear and an A-type curve in the right one. Nuclear magnetic resonance (NMR) scan revealed a mass 2 cm 2 cm in size in the left nasopharynx (Fig. 1). The surgical treatment involved a transfacial excision performed via a lateronasal approach with nasomaxillary pedicled flap, as previously described by the senior author (F.B.) [11]. The skin was incised starting at the inner tip of the eyebrow, proceeding in a Z shape as far as the caudal edge of the nasal bone, and continuing around the nostril to the piriform opening (Fig. 2). After detaching laterally the soft tissues of the orbit and cheek, three osteotomies were done to prepare the nasomaxillary flap, to expose the nasal fossa and nasopharynx (Fig. 3). During surgery the mass was noted to enter the left Eustachian tube, which was partially resected in order to assure a complete excision with clear margins. The surgical specimen (Fig. 4) revealed a 2 cm 3 cm, greyish, lobulated mass; it was firm in consistence, and grossly well circumscribed. Fig. 2. Z-shaped lateronasal skin incision.
Fig. 1. First axial NMR scan (1998) reveals tumour of the left nasopharynx.
The patient was followed up for 84 months without any sign of tumour recurrence; a CT performed in June 2004 failed to reveal any evidence of disease. In January 2005 the patient presented with a complaint of right nasal obstruction and homolateral mucopurulent secretions. She underwent a computed tomography which showed a solid tumour arising from the right lateral nasopharyngeal wall. NMR revealed that the mass had sharply defined margins and did not infiltrate either the pterygoid muscle or the surrounding bones (Fig. 5). On the left half of nasopharynx there was no sign of recurrence. The patient underwent a fine needle aspiration biopsy which was consistent with a myoepithelioma. A partial right maxillectomy via a lateronasal approach with nasomaxillary pedicled flap [11] was performed. Intraoperatively the tumour was noted to origin from the right Eustachian tube, which had to be partially sacrificed. Histologically, the tumour was surrounded by a thin pseudocapsule and had an expansive growth pattern. Microscopic appearance in both cases was remarkably similar and characterized by a diffuse solid pattern of growth with an overall vague lobular architecture formed by large nests of polyhedral cells with optically clear cytoplasm and round nuclei with inconspicuous nucleoli (Fig. 6A and B).
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E. Gaio et al. / Auris Nasus Larynx 36 (2009) 496–500
Fig. 5. In 2005 an NMR scan demonstrates a right nasopharynx mass.
Fig. 3. Surgical approach to nasopharynx.
The stroma was pale eosinophilic and showed only focally a myxoid alcianophylic quality. Neither mitotic figures, nor areas of necrosis were observed after an extensive sampling of the surgical specimen. Immunohistochemically, the tumour cells reacted strongly to S100-protein, cytokeratin-14, cytokeratin-5/6, smooth-muscle actin, calponin and p63 protein (Fig. 6C–H). The patient has no evidence of recurrence to date at 39 months’ follow-up (Fig. 7).
3. Discussion
Fig. 4. Macroscopic appearance of surgical specimen.
To the best of our knowledge, only three cases more of sinonasal myoepithelioma have been described in the literature to date. In 1989, Dardick et al. [12] briefly mentioned the first case, the second was thoroughly described by Be´gin et al. in 1991 [3], the last was published by Lateef et al. in 1999 [5]. All of the patients described in literature (considering also our case) were middle-aged females (average: 66.5, range: 64–69 years), whose major complaint was nasal obstruction; only 1 patient reported epistaxis [3]. The mass originated from the inferior turbinate in one case [3], from the nasal piriform aperture in another [5], from the nasopharynx in our case. Only Be´gin et al. [3] gave sufficient information about follow-up since no recurrence was registered 33 months after the surgery.
E. Gaio et al. / Auris Nasus Larynx 36 (2009) 496–500
499
Fig. 6. Nests of polyhedral cells with optically clear cytoplasms and round nuclei with inconspicuous nucleoli [hematoxylin and eosin stain, original magnification 100 (A); original magnification 250 (B)]. Myoepithelioma tumour cells showing strong immunoreactivity for S100-protein (C), cytokeratin14 (D), cytokeratin-5/6 (E), smooth-muscle actin (F), calponin (G) and p63 (H) [original magnification 250].
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E. Gaio et al. / Auris Nasus Larynx 36 (2009) 496–500
must be aware that malignant myoepitheliomas can be composed of cytologically bland elements, for this reason a generous sampling of the periphery of tumour at the interface with the surrounding tissue is adviced, to rule out any evidence of infiltrative growth [13]. Although histologic variants are not thought to be prognostically predictive, the clear cell variant may have an unpredictable clinical course, despite its deceptive morphology [13]. An overall recurrence rate of 18% has been reported, and the recurrence rate is higher (42%) for those tumours with aggressive features [8]. The prognosis of soft tissue myoepitheliomas remains uncertain, although most behave benign; it is probable that its optimal treatment is a wide local excision with clear surgical margins [4]. As for pleomorphic adenoma, longterm follow-up may be required to assess potential recurrence or multicentric tumours [3].
Fig. 7. Last NMR scan (performed in December 2007), which confirms no relapses.
The present case represents the first report of a metachronous myoepithelioma originated bilaterally in the nasopharynx. The resection of the left myoepithelioma was conducted with wide and pathologically free margins in order to assure radicality. The right nasopharyngeal wall was carefully preserved during surgical excisions, trying to avoid tumour cells seeding. Unfortunately we do not have any information about the three previously performed surgical excision of the left myoepithelioma, so that we are not able to assure that tumour seeding can be excluded at all. However we reviewed CT scans done before our first surgical treatment, and all right nasopharyngeal structures were macroscopically free of tumour. 84 months after radical excision of the left nasopharyngeal myoepithelioma an analogous lesion appeared contralaterally. If we exclude the tumour seeding during the three previous attempts to remove the left myoepithelioma, the right localization might be due to the lymphatic or haematogenous spread or to the multicentric presence of embryonic rest of minor salivary gland tissue, which is considered the origin of most myoepitheliomas [5]. The biologic potential of myoepitheliomas is uncertain, a meta-analysis study of 42 previously reported myoepithelial tumours of the head and neck found that 93% of them were benign, whereas only 7% pursued a malignant course [13]. Hornick and Fletcher [9] suggest that soft tissue myoepithelial tumours with at least moderate cytologic atypia should be considered clinically malignant. Nevertheless, one
References [1] Spiro RH. Salivary neoplasms: overview of a 35-year experience with 2,807 patients. Head Neck Surg 1986;8:177–84. [2] Amilibia E, Nogues J, Sandoval M, Arias G, Dicenta M. Tumor de gla´ndulas salivares menores en rinofaringe. Acta Otorrinolaring Esp 1997;48:671–3. [3] Be´gin LR, Rochon L, Frenkiel S. Spindle cell myoepithelioma of the nasal cavity. Am J Surg Pathol 1991;15:184–90. [4] Venkatraman L, Sinnathuray AR, Raut V, Brooker DS, McCluggage WG. Soft tissue myoepithelioma: a case report. Pathology 2002;34:451–4. [5] Lateef SS, Castillo M, Mukherji SK, Cooper LL. Myoepithelioma of the nasal piriform aperture: CT findings. Am J Roentgenol 1999;173:1413–4. [6] Testa D, Galera F, Insabato L, Vassallo A, Mesolella M, Galli V. Submandibular gland myoepithelioma. Acta Otolaryngol 2005;125: 664–6. [7] Michal M, Miettinen M. Myoepitheliomas of the skin and soft tissues. Virchows Arch 1999;434:393–400. [8] Galvao Neto A, Pineda-Daboin K, Luna MA. Myoepithelioma of the soft tissue of the head and neck: a case report and review of the literature. Head Neck 2004;26:470–3. [9] Hornick JL, Fletcher CDM. Myoepithelial tumors of soft tissue. Am J Surg Pathol 2003;27:1183–96. [10] El-Naggar AK, Lovell M, Callender DL, Ordonez NG, Killary AM. Cytogenetic analysis of a primary salivary gland myoepithelioma. Cancer Genet Cytogenet 1999;113:49–53. [11] Bagatella F, Mazzoni A. Microsurgery in juvenile nasopharyngeal angiofibroma: a lateronasal approach with nasomaxillary pedicled flap. Skull Base Surg 1995;5:219–26. [12] Dardick I, Thomas MJ, Van Nostrand AWP. Myoepithelioma—new concepts of histology and classification: a light and electron microscopic study. Ultrastruct Pathol 1989;13:87–224. [13] Nayak JV, Molina T, Smith JC, Branstetter BF, Hunt JL, Snyderman CH. Myoepithelial neoplasia of the submandibular gland. Arch Otolaryngol Head Neck Surg 2003;129:359–62.
Bilateral myoepithelioma of the nasopharynx: A case report Elena Gaio a,*, Antonio Perasole b, Francesco Bagatella a a
Department of Otolaryngology-Head and Neck Surgery, City Hospital, Castelfranco Veneto, Italy b Department of Pathology, City Hospital, Castelfranco Veneto, Italy Received 18 March 2008; accepted 28 October 2008 Available online 30 December 2008
Abstract Myoepithelioma is a rare salivary tumour which is usually encountered in the parotid gland. Outside the parotid, myoepithelioma may arise from minor salivary glands of the hard palate and less frequently in bronchi or breast. In this report we describe the unique case of a metachronous bilateral nasopharyngeal myoepithelioma arising from the tubaric regions. Its microscopic features, immunophenotype, and the differential diagnosis together with a review of literature are discussed. # 2008 Elsevier Ireland Ltd. All rights reserved. Keywords: Nasopharynx; Myoepithelioma; Minor salivary gland
1. Introduction Neoplasms of minor salivary gland origin are rare in the sinonasal tract; in 1986 Spiro [1] revised 2807 consecutive cases of salivary neoplasm: 150 were localized in paranasal sinuses, only 9 (0.3%) arose in the nasopharynx [2]. The majority of cases of sinonasal salivary neoplasms usually are represented by pleomorphic adenomas [3]. Myoepitheliomas are rare tumours which are best defined in the major salivary glands, although they have been reported also in breast and lungs [4]. They account for less than 1% of all salivary neoplasms; the parotid gland and the minor glands of the hard palate are the most common sites of occurrence [5,6]. Their constituting element derives from myoepithelial cells that surround the salivary acina and intercalated ducts, exhibiting immunohistochemical and ultrastructural features of both epithelial and smooth-muscle cells [7]. Neoplastic myoepithelial cells may have different morphologies (epithelioid, spindle, plasmacytoid, and clear cell), and only occasionally they can have a biphasic pattern [8]. The considerable overlap in the histologic appearances * Corresponding author. Present address: via Madonna dei Prati 27 bis, 36040 Brendola (VI), Italy. Tel.: +39 0338 3090070; fax: +39 0444 401728. E-mail address: [email protected] (E. Gaio).
of pleomorphic adenomas and myoepitheliomas has lead many investigators to think that these tumours lie on a morphologic continuum [5,9] spanning from myoepithelioma (composed only by myoepithelial cells) to canalicular adenoma (composed only by epithelial duct cells). At the midpoint lie pleomorphic adenomas, constituted by proliferated myoepithelial cells and epithelial duct elements in variable proportion, embedded in a myxochondroid stroma of myoepithelial derivation. The close relationship between myoepithelioma and pleomorphic adenoma has also been investigated through cytogenetic studies: myoepitheliomas share the chromosome 12q alteration reported in a subset of pleomorphic adenomas [10]. The characteristic plasticity of myoepithelial cells, the resultant broad morphologic spectrum of myoepithelial tumours and the potential of myoepithelioma to originate outside major salivary glands account for the difficulties often experienced in its correct diagnosis.
2. Case report A 47-year-old woman presented to our Department in January 1998 with a 3-month history of left nasal obstruction and aural fullness. Three times earlier (in 1991, 1992 and 1994) she had already undergone in another hospital surgical
0385-8146/$ – see front matter # 2008 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.anl.2008.10.007
E. Gaio et al. / Auris Nasus Larynx 36 (2009) 496–500
497
excision of a left nasopharyngeal mass which was diagnosed as myoepithelioma. Unfortunately we could not access any information about her previous surgical treatments. On otolaryngological examination, the patient presented a large exophytic tumour growing from the left posterolateral nasopharyngeal wall occupying the homolateral half of the nasopharynx. The remainder of otolaryngological examination showed a retracted left tympanic membrane with limpid transudate behind it. A pure-tone audiometry revealed a left conductive hearing loss; the tympanogram showed a Jerger B-type curve in the left ear and an A-type curve in the right one. Nuclear magnetic resonance (NMR) scan revealed a mass 2 cm 2 cm in size in the left nasopharynx (Fig. 1). The surgical treatment involved a transfacial excision performed via a lateronasal approach with nasomaxillary pedicled flap, as previously described by the senior author (F.B.) [11]. The skin was incised starting at the inner tip of the eyebrow, proceeding in a Z shape as far as the caudal edge of the nasal bone, and continuing around the nostril to the piriform opening (Fig. 2). After detaching laterally the soft tissues of the orbit and cheek, three osteotomies were done to prepare the nasomaxillary flap, to expose the nasal fossa and nasopharynx (Fig. 3). During surgery the mass was noted to enter the left Eustachian tube, which was partially resected in order to assure a complete excision with clear margins. The surgical specimen (Fig. 4) revealed a 2 cm 3 cm, greyish, lobulated mass; it was firm in consistence, and grossly well circumscribed. Fig. 2. Z-shaped lateronasal skin incision.
Fig. 1. First axial NMR scan (1998) reveals tumour of the left nasopharynx.
The patient was followed up for 84 months without any sign of tumour recurrence; a CT performed in June 2004 failed to reveal any evidence of disease. In January 2005 the patient presented with a complaint of right nasal obstruction and homolateral mucopurulent secretions. She underwent a computed tomography which showed a solid tumour arising from the right lateral nasopharyngeal wall. NMR revealed that the mass had sharply defined margins and did not infiltrate either the pterygoid muscle or the surrounding bones (Fig. 5). On the left half of nasopharynx there was no sign of recurrence. The patient underwent a fine needle aspiration biopsy which was consistent with a myoepithelioma. A partial right maxillectomy via a lateronasal approach with nasomaxillary pedicled flap [11] was performed. Intraoperatively the tumour was noted to origin from the right Eustachian tube, which had to be partially sacrificed. Histologically, the tumour was surrounded by a thin pseudocapsule and had an expansive growth pattern. Microscopic appearance in both cases was remarkably similar and characterized by a diffuse solid pattern of growth with an overall vague lobular architecture formed by large nests of polyhedral cells with optically clear cytoplasm and round nuclei with inconspicuous nucleoli (Fig. 6A and B).
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E. Gaio et al. / Auris Nasus Larynx 36 (2009) 496–500
Fig. 5. In 2005 an NMR scan demonstrates a right nasopharynx mass.
Fig. 3. Surgical approach to nasopharynx.
The stroma was pale eosinophilic and showed only focally a myxoid alcianophylic quality. Neither mitotic figures, nor areas of necrosis were observed after an extensive sampling of the surgical specimen. Immunohistochemically, the tumour cells reacted strongly to S100-protein, cytokeratin-14, cytokeratin-5/6, smooth-muscle actin, calponin and p63 protein (Fig. 6C–H). The patient has no evidence of recurrence to date at 39 months’ follow-up (Fig. 7).
3. Discussion
Fig. 4. Macroscopic appearance of surgical specimen.
To the best of our knowledge, only three cases more of sinonasal myoepithelioma have been described in the literature to date. In 1989, Dardick et al. [12] briefly mentioned the first case, the second was thoroughly described by Be´gin et al. in 1991 [3], the last was published by Lateef et al. in 1999 [5]. All of the patients described in literature (considering also our case) were middle-aged females (average: 66.5, range: 64–69 years), whose major complaint was nasal obstruction; only 1 patient reported epistaxis [3]. The mass originated from the inferior turbinate in one case [3], from the nasal piriform aperture in another [5], from the nasopharynx in our case. Only Be´gin et al. [3] gave sufficient information about follow-up since no recurrence was registered 33 months after the surgery.
E. Gaio et al. / Auris Nasus Larynx 36 (2009) 496–500
499
Fig. 6. Nests of polyhedral cells with optically clear cytoplasms and round nuclei with inconspicuous nucleoli [hematoxylin and eosin stain, original magnification 100 (A); original magnification 250 (B)]. Myoepithelioma tumour cells showing strong immunoreactivity for S100-protein (C), cytokeratin14 (D), cytokeratin-5/6 (E), smooth-muscle actin (F), calponin (G) and p63 (H) [original magnification 250].
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E. Gaio et al. / Auris Nasus Larynx 36 (2009) 496–500
must be aware that malignant myoepitheliomas can be composed of cytologically bland elements, for this reason a generous sampling of the periphery of tumour at the interface with the surrounding tissue is adviced, to rule out any evidence of infiltrative growth [13]. Although histologic variants are not thought to be prognostically predictive, the clear cell variant may have an unpredictable clinical course, despite its deceptive morphology [13]. An overall recurrence rate of 18% has been reported, and the recurrence rate is higher (42%) for those tumours with aggressive features [8]. The prognosis of soft tissue myoepitheliomas remains uncertain, although most behave benign; it is probable that its optimal treatment is a wide local excision with clear surgical margins [4]. As for pleomorphic adenoma, longterm follow-up may be required to assess potential recurrence or multicentric tumours [3].
Fig. 7. Last NMR scan (performed in December 2007), which confirms no relapses.
The present case represents the first report of a metachronous myoepithelioma originated bilaterally in the nasopharynx. The resection of the left myoepithelioma was conducted with wide and pathologically free margins in order to assure radicality. The right nasopharyngeal wall was carefully preserved during surgical excisions, trying to avoid tumour cells seeding. Unfortunately we do not have any information about the three previously performed surgical excision of the left myoepithelioma, so that we are not able to assure that tumour seeding can be excluded at all. However we reviewed CT scans done before our first surgical treatment, and all right nasopharyngeal structures were macroscopically free of tumour. 84 months after radical excision of the left nasopharyngeal myoepithelioma an analogous lesion appeared contralaterally. If we exclude the tumour seeding during the three previous attempts to remove the left myoepithelioma, the right localization might be due to the lymphatic or haematogenous spread or to the multicentric presence of embryonic rest of minor salivary gland tissue, which is considered the origin of most myoepitheliomas [5]. The biologic potential of myoepitheliomas is uncertain, a meta-analysis study of 42 previously reported myoepithelial tumours of the head and neck found that 93% of them were benign, whereas only 7% pursued a malignant course [13]. Hornick and Fletcher [9] suggest that soft tissue myoepithelial tumours with at least moderate cytologic atypia should be considered clinically malignant. Nevertheless, one
References [1] Spiro RH. Salivary neoplasms: overview of a 35-year experience with 2,807 patients. Head Neck Surg 1986;8:177–84. [2] Amilibia E, Nogues J, Sandoval M, Arias G, Dicenta M. Tumor de gla´ndulas salivares menores en rinofaringe. Acta Otorrinolaring Esp 1997;48:671–3. [3] Be´gin LR, Rochon L, Frenkiel S. Spindle cell myoepithelioma of the nasal cavity. Am J Surg Pathol 1991;15:184–90. [4] Venkatraman L, Sinnathuray AR, Raut V, Brooker DS, McCluggage WG. Soft tissue myoepithelioma: a case report. Pathology 2002;34:451–4. [5] Lateef SS, Castillo M, Mukherji SK, Cooper LL. Myoepithelioma of the nasal piriform aperture: CT findings. Am J Roentgenol 1999;173:1413–4. [6] Testa D, Galera F, Insabato L, Vassallo A, Mesolella M, Galli V. Submandibular gland myoepithelioma. Acta Otolaryngol 2005;125: 664–6. [7] Michal M, Miettinen M. Myoepitheliomas of the skin and soft tissues. Virchows Arch 1999;434:393–400. [8] Galvao Neto A, Pineda-Daboin K, Luna MA. Myoepithelioma of the soft tissue of the head and neck: a case report and review of the literature. Head Neck 2004;26:470–3. [9] Hornick JL, Fletcher CDM. Myoepithelial tumors of soft tissue. Am J Surg Pathol 2003;27:1183–96. [10] El-Naggar AK, Lovell M, Callender DL, Ordonez NG, Killary AM. Cytogenetic analysis of a primary salivary gland myoepithelioma. Cancer Genet Cytogenet 1999;113:49–53. [11] Bagatella F, Mazzoni A. Microsurgery in juvenile nasopharyngeal angiofibroma: a lateronasal approach with nasomaxillary pedicled flap. Skull Base Surg 1995;5:219–26. [12] Dardick I, Thomas MJ, Van Nostrand AWP. Myoepithelioma—new concepts of histology and classification: a light and electron microscopic study. Ultrastruct Pathol 1989;13:87–224. [13] Nayak JV, Molina T, Smith JC, Branstetter BF, Hunt JL, Snyderman CH. Myoepithelial neoplasia of the submandibular gland. Arch Otolaryngol Head Neck Surg 2003;129:359–62.