International Journal of Pediatric Otorhinolaryngology Extra
Volume 2, Issue 1 , Pages 1-5, March 2007

Childhood acinic cell carcinoma of the accessory parotid gland: A rare combination

  • Shelby C. Leuin

      Affiliations

    • Department of Otolaryngology, Massachusetts Eye and Ear Infirmary, 243 Charles Street, Boston, MA 02114, United States
    • Corresponding Author InformationCorresponding author. Tel.: +1 617 780 8780.
    • ,
  • Michael J. Cunningham

      Affiliations

    • Department of Otolaryngology, Massachusetts Eye and Ear Infirmary, 243 Charles Street, Boston, MA 02114, United States
    • Tel.: +1 617 573 4250.
    • ,
  • Hugh Curtin

      Affiliations

    • Department of Radiology, Massachusetts Eye and Ear Infirmary, 243 Charles Street, Boston, MA 02114, United States
    • Tel.: +1 617 573 3563.
    • ,
  • William C. Faquin

      Affiliations

    • Department of Pathology, Massachusetts Eye and Ear Infirmary, 243 Charles Street, Boston, MA 02114, United States
    • Tel.: +1 617 573 3957.

Received 31 July 2006; accepted 16 August 2006.

Article Outline

Summary 

Tumors of the accessory parotid gland are rare, extremely so in the pediatric population. This is only the second reported case of an acinic cell carcinoma of the accessory parotid gland in a child. His clinical presentation, physical examination, unusual radiographic features, and confirmatory histopathologic findings are described. The preferred treatment is complete surgical excision with adjuvant radiotherapy in certain “at risk” patients.

Keywords: Acinic cell carcinoma, Parotid gland, Histopathology, Vascular tumor

 

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1. Introduction 

The differential diagnosis for an anterior facial buccal region mass encompasses a wide variety of histopathologic lesions. Most prominent are lesions of salivary gland origin including benign and malignant neoplasms, vascular tumors and malformations, and congenital branchial cyst anomalies. Less frequent are reactive lymphadenopathy, adnexal, neural or mesenchymal tumors, and metastatic lesions.

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2. Case report 

A 12-year-old boy presented with a 6–8 week history of a left cheek mass. He had no history of antecedent trauma and denied associated facial pain, numbness, or weakness. He had been in good health with no fevers, night sweats, or weight loss.

Physical examination revealed a healthy appearing adolescent male with a firm, nontender left cheek mass. The mass approximated 3.0cm in diameter and became more prominent when he clenched his teeth. Although clearly palpable externally, the mass was not appreciable on intraoral examination. The mass was immobile but not fixed to the overlying skin. Its location was grossly judged as buccal, anterior to the parotid gland. There were no additional cervicofacial masses or lymphadenopathy. Facial nerve function was symmetric bilaterally. The remainder of the otolaryngologic examination was unremarkable.

Magnetic resonance imaging with and without contrast revealed an oval-shaped, well circumscribed abnormality deep to the subcutaneous fat of the left cheek, superficial to the left masseter muscle, and anterior to the left parotid gland (Fig. 1). It measured 2.8cm×2.2cm. There was no evidence of invasion of surrounding structures. The lesion was bright both on T1- and T2-weighted images, suggesting proteinaceous fluid or hemorrhage. The wall was very thin. There was no appreciable contrast enhancement within the abnormality. A small part of the accessory parotid gland was identified at the superior margin of the lesion.

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  • Fig. 1. 

    (A) Sagittal T1 weighted image shows oval abnormality (arrow) containing high signal. This signal remained after fat suppression, excluding fat as the etiology. (B) Axial T2 weighted image. The lesion (arrow) shows high signal. (C) Coronal T2 weighted image. The lesion (black arrow) indents the masseter muscle. A small part of residual accessory parotid tissue (small white arrow) is seen at the superior margin of the lesion. Compare with the accessory parotid gland (large white arrow) on the right side.

The patient underwent excision of the left cheek mass via a rhytidectomy approach. Intraoperatively the mass was clearly anterior to the parotid gland and was separable from the masseter muscle. It was excised in total although with spillage of its hemorrhagic fluid contents just prior to its complete removal.

The resected specimen measured 2.7cm×2.0cm×1.7cm, and on sectioning, consisted of a 2.2cm cystic cavity with a firm fibrous wall surrounded by tan-yellow fibroadipose tissue. Microscopic examination revealed a predominantly cystic neoplasm with a thin lining of neoplastic epithelial cells (Fig. 2A). These neoplastic cells were characterized by abundant vacuolated, basophilic cytoplasm and uniform round to oval nuclei that were eccentrically located and contained a small distinct nucleolus (Fig. 2B). Occasional small basophilic cytoplasmic granules suggestive of serous-type acinar differentiation were present (Fig. 2C). Focally, groups of tumor cells exhibited a papillary architecture with a fibrovascular core, and some cells within the groups surrounded microcystic spaces. These histologic findings were diagnostic of a papillary-cystic variant of acinic cell carcinoma.

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  • Fig. 2. 

    (A) Low magnification image showing a cystic neoplasm within salivary gland parenchyma. (B) A higher magnification image shows some areas of the tumor to exhibit a papillary architecture. (C) A high magnification image demonstrates tumor cells with delicate basophilic cytoplasm, focal cytoplasmic granules, vacuoles, and microcystic spaces.

Pediatric oncology consultation was requested. Due to the intraoperative spillage of tumor contents, postoperative radiotherapy was recommended. A total of 60 gray was administered over 8 weeks in stereotactic proton beam fashion.

The patient is currently clinically disease free 18 months status post excision. Follow up imaging performed at 1 year postoperatively showed stable surgical changes with no evidence of recurrent tumor.

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3. Discussion 

Cadaveric studies have shown that approximately 21% of the human population has accessory parotid tissue distinct from the parotid gland [4]. Such accessory parotid tissue usually has an organized glandular segment with secondary ducts that ultimately drain into Stenson's duct. The most common location is on the masseter muscle or within the buccal fat pad, usually between the buccal and zygomatic branches of the facial nerve, on average 6mm anterior to the parotid gland. Accessory parotid tissue is often clinically detectable only when there is an inherent abnormality or disease process.

Evaluation of buccal space masses and potential accessory parotid gland lesions consists principally of roentgenographic studies and fine needle aspiration biopsy. Ultrasound allows differentiation of the mass from the surrounding facial structures and can characterize the mass as cystic or solid. Computed tomography provides additional soft tissue detail and is best for identifying calculi and calcifications. Magnetic resonance imaging is advantageous in that it gives more precise information regarding soft tissue characteristics and anatomical mass location. For specific tissue diagnosis, fine needle aspiration remains the modality of choice.

Information is very limited regarding accessory parotid gland lesions in children. A recently published 13 year review of the surveillance, epidemiology, and end results (SEER) database identified 113 primary salivary gland malignancies in the pediatric age range, but none of accessory parotid origin [9]. Five pediatric accessory parotid gland lesions were described in a recent radiology publication including one acinic cell carcinoma in a 10-year-old female [8]. The other pathologic diagnoses in this series were a hemangioma, a mucoepidermoid carcinoma, a congenital fistula from the accessory parotid to the skin surface, and a case of metastatic B cell lymphoblastic leukemia [2].

Of all parotid gland tumors, an estimated 1–8% are of accessory parotid gland origin. Lesions of the accessory parotid in adults are usually neoplastic and include both benign and malignant tumors; a rate of malignancy has been reported as 26% in contrast to the 18.5% figure quoted for the parotid gland proper [7]. There have been three reported adult cases of acinic cell carcinoma of the accessory parotid gland [2], [1].

Acinic cell carcinoma is the second most common salivary gland malignancy after mucoepidermoid carcinoma in children 12 years of age or younger [9]. It tends to occur at an earlier age than other salivary gland cancers, and has an incidence which is slightly greater in females than in males. Acinic cell carcinoma is believed to arise from progenitor reserve cells of the intercalated ducts of salivary tissue. Although characteristically slow growing with clinical behavior reflective of a low-grade tumor, acinic cell carcinoma can recur in 25–50% of patients if not treated adequately [10]. A subset of acinic cell carcinomas are clinically more aggressive with metastasis to regional lymph nodes and distant sites, particularly the lung, at presentation. Histologic grading of acinic cell carcinomas is controversial and, unlike clinical stage, histomorphology has not proven to be reliable in predicting behavior. The diagnosis of acinic cell carcinoma in both cytologic and resection specimens requires documentation of focal serous acinar differentiation, the hallmark of this tumor. When the tumor is composed of predominantly solid acinar-type cells, the diagnosis is straightforward. The wide range of cell types and architectural patterns that can be seen in some cases yields a broader differential diagnosis, which includes mucoepidermoid carcinoma, oncocytoma, cystadenoma, and cystadenocarcinoma. The identification of serous-type acinar differentiation and the absence of epidermoid and mucinous cells distinguishes acinic cell carcinoma from these other neoplasms. For diagnostically difficult cases, periodic acid Schiff (PAS) plus diastase, a special staining technology, can be used as an ancillary histochemical marker to highlight the cytoplasmic zymogen granules characteristic of acinar cells.

Prognostic data is extrapolated from adult studies with 5-year survival estimated to be 84% [3]. Surgical outcomes experience in adults with acinic cell carcinoma suggests that the best survival results are achieved when there is complete tumor excision at initial surgery. Adjuvant therapy, specifically postoperative radiation, is recommended in the treatment of primary parotid gland acinic cell carcinoma if there are positive margins, tumor spillage, tumor inseparable from the facial nerve, deep lobe involvement, lymph node metastases, extraparotid extension, or tumors >4cm [6]. In this “at risk” population, the addition of radiotherapy following surgical excision increases survival from 29% to 41.5% [5]. The intraoperative spillage of tumor contents prompted the use of postoperative radiotherapy in this patient.

In summary, neoplasms of accessory parotid gland origin are extremely rare in the pediatric population. There has been only one previous report of acinic cell carcinoma within the accessory parotid tissue of a child. The treatment of choice is complete surgical excision, with adjuvant radiotherapy reserved for the perioperative indications outlined above.

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References 

  1. Barbashina V, Harawi S. Pathologic quiz case. Acinic cell adenocarcinoma of accessory right parotid gland. Arch. Pathol. Lab. Med. 2000 Dec;124(12):1835–1836
  2. Currarino G, Votteler TP. Lesions of the accessory parotid gland in children. Pediatr. Radiol. 2006 Jan;36(1):1–7
  3. Ellis GL, Auclair PL. Malignant epithelial tumors. Armed Forces Institute of Pathology. Atlas of Tumor Pathology: Tumors of the Salivary Glands. Third Series fascicle, vol. 17. Bethesda: Universities Associated for Research and Education in Pathology, Inc.; 1996;p. 183
  4. Frommer J. The human accessory parotid gland: its incidence, nature, and significance. Oral. Surg. Oral. Med. Oral. Pathol. 1977;43(5):671–676
  5. Hoffman HT, Karnell LH, Robinson RA, Pinkston JA, Menck HR. National Cancer Data Base report on cancer of the head and neck: acinic cell carcinoma. Head Neck. 1999;21(4):297–309
  6. Kaplan MJ, Johns ME, Cantrell RW. Chemotherapy for salivary gland cancer. Otolaryngol. Head Neck Surg. 1986 Sep;95(2):165–170
  7. Perzik SL, White IL. Surgical management of preauricular tumors of the accessory parotid apparatus. Am. J. Surg. 1966 Oct;112(4):498–503
  8. Rejmanowski T. Lobular carcinoma of accessory parotid in a 10-year-old girl. Pediatr. Pol. 1971;46(12):1545–1547
  9. Shapiro NL, Bhattacharyya N. Clinical characteristics and survival for major salivary gland malignancies in children. Otolaryngol. Head Neck Surg. 2006;134(4):631–634
  10. Spafford PD, Mintz DR, Hay J. Acinic cell carcinoma of the parotid gland: review and management. J. Otolaryngol. 1991;20(4):262–266

PII: S1871-4048(06)00081-5

doi:10.1016/j.pedex.2006.08.002

International Journal of Pediatric Otorhinolaryngology Extra
Volume 2, Issue 1 , Pages 1-5, March 2007

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