Sclerosing Polycystic Adenosis: A Rare Tumor of the Salivary Glands

Sclerosing Polycystic Adenosis: A Rare Tumor of the Salivary Glands

 

Christopher G Tang, MD; Justin B Fong; Karen L Axelsson, MD; Deepak Gurushanthaiah, MD

Perm J 2016 Spring;20(2):e113-e114

https://doi.org/10.7812/TPP/15-147

Abstract

Case Presentation: A 74-year-old woman presented to the Head and Neck Surgery clinic with a 4-year history of a slowly growing, painful, left-sided neck mass in the tail of the parotid gland. Fine-needle aspiration suggested well-differentiated adenocarcinoma.
Discussion and Results: The patient underwent a superficial parotidectomy and super-selective neck dissection (level 2). Pathology revealed a tumor consistent with sclerosing polycystic adenosis.
Conclusion: Sclerosing polycystic adenosis is a rare inflammatory process that causes fibrocystic changes in the salivary gland. Apocrine-like metaplasia and epithelial atypia are common pathologic features. To our knowledge, a total of 51 cases have been described in the English-language literature.

Introduction

Sclerosing polycystic adenosis (SPA) is a rare, reactive, inflammatory lesion of the salivary glands resulting in fibrocystic changes and adenosis, similar to what occurs in the mammary glands.1 Lesions present as slow-growing masses in salivary gland parenchyma. They are discrete, pale, and rubbery nodules. The tumors are not encapsulated but are well defined. Pathologically, they display dense sclerotic lobules and cystic change with hyalinized collagen separation. Apocrine-like metaplasia; epithelial atypia; and ductal, acinar hyperplasia are commonly observed. A distinguishing feature of this lesion is focal cystic spaces within the fibrotic stoma. Most observed cases occur in the parotid gland.1-4 We report a typical case of SPA occurring in the parotid gland.

Case presentation

A 74-year-old woman presented to the Head and Neck Surgery clinic at the Kaiser Permanente Medical Center in Oakland, CA, with a 4-year history of a growing, painful, left-sided neck mass. Two years before presentation, the patient underwent fine-needle aspiration with negative results for malignancy and did not pursue further workup. The mass persisted and continued to enlarge. The patient now had a firm 3.5-cm mass in the tail of the left parotid gland without overlying erythema. Fine-needle aspiration suggested a well-differentiated adenocarcinoma. Magnetic resonance imaging showed a well-defined, peripherally enhancing 3.5-cm lobe mass (Figures 1 and 2). Surgery was scheduled, and a superficial parotidectomy and a selective neck dissection (level 2) were performed. Final pathology revealed a 3.5-cm, well-circumscribed tumor consistent with SPA (Figures 3-5).

Sclerosing Polycystic Adenosis: A Rare Tumor of the Salivary Glands

Sclerosing Polycystic Adenosis: A Rare Tumor of the Salivary Glands

Sclerosing Polycystic Adenosis: A Rare Tumor of the Salivary Glands

Discussion and results

SPA is a rare, benign tumor of the salivary glands, which was first described in 1996.5 About 80% of SPA cases present in the major salivary glands—specifically, the parotid gland.1 However, cases have been observed in the minor salivary glands of the nasal septum,2 buccal mucosa,3 hard palate, floor of the mouth, and retromolar pad.4 SPA has also been reported in the lacrimal gland.3 SPA is equally common in men and women, and reported cases have a wide age of distribution.1

Usually, parotid SPA comprises deep-seated, slow-growing, round, palpable masses. Pain and tenderness may be present. The masses are multinodular, with cysts 1 mm to 2 mm in diameter. SPA may be multifocal.1-8

Histologically, SPA is characterized by acinar cells with robust eosinophilic structures similar to zymogen granules. Ductal epithelial atypia is common, and epithelial cells exhibit various cells of apocrine, foamy, vacuolated, and mucinous nature.1-4 The lobular architecture usually includes atypical nests of myoepithelial cells.1-4 However, infiltrative carcinoma growth does not occur.6

SPA is considered benign. However, one case of ductal carcinoma in situ has been reported.6 Most cases of SPA are treated with localized surgical resection with clear margins.8 Recurrence has been reported in up to one-third of cases. Recurrence generally occurs because of inadequate surgical resection and because of the multifocality of the SPA.8 We found no cases of death or of metastasis attributed to SPA in a MEDLINE literature search.

There is a high chance of misdiagnosis because of the rarity of the disease and because clinicians and pathologists may be unfamiliar with it; for example, the present case was initially diagnosed as a well-differentiated adenocarcinoma.2 Differential diagnosis included adenoma; benign polycystic disease; sclerosing sialadenitis; and malignant glandular neoplasias, such as mucoepidermoid carcinoma, acinic cell carcinoma, adenocarcinoma NOS (not otherwise specified), and salivary duct carcinoma.2

Our case was a 3.5-cm mass in the tail of the parotid gland. Presentation in the parotid gland and histologic findings of cysts and lobular architecture with collagen separation are characteristic of SPA.

Conclusion

SPA is a rare inflammatory process that causes fibrocystic changes in the salivary gland. Apocrine-like metaplasia and epithelial atypia are common features. To our knowledge, only 51 cases have been described in the English literature.9

Disclosure Statement

The author(s) have no conflicts of interest to disclose.

Acknowledgment

Leslie Parker, ELS, provided editorial assistance.

References
1.    Petersson F. Sclerosing polycystic adenosis of salivary glands: a review with some emphasis on intraductal epithelial proliferations. Head Neck Pathol 2013 Jul;7 Suppl 1:S97-106. DOI: https://doi.org/10.1007/s12105-013-0465-9.
    2.    Park IH, Hong SM, Choi H, Chang H, Lee HM. Sclerosing polycystic adenosis of the nasal septum: the risk of misdiagnosis. Clin Exp Otorhinolaryngol 2013 Jun;6(2):107-9. DOI: https://doi.org/10.3342/ceo.2013.6.2.107.
    3.    Meer S, Altini M. Sclerosing polycystic adenosis of the buccal mucosa. Head Neck Pathol 2008 Mar;2(1):31-5. DOI: https://doi.org/10.1007/s12105-008-0042-9.
    4.    Mokhtari S, Atarbashi Moghadam S, Mirafsharieh A. Sclerosing polycystic adenosis of the retromolar pad area: a case report. Case Rep Pathol 2014;2014:982432. DOI: https://doi.org/10.1155/2014/982432.
    5.    Smith BC, Ellis GL, Slater LJ, Foss RD. Sclerosing polycystic adenosis of major salivary glands. A clinicopathologic analysis of nine cases. Am J Surg Pathol 1996 Feb;20(2):161-70. DOI: https://doi.org/10.1097/00000478-199602000-00004.
    6.    Petersson F, Tan PH, Hwang JS. Sclerosing polycystic adenosis of the parotid gland: report of a bifocal, paucicystic variant with ductal carcinoma in situ and pronounced stromal distortion mimicking invasive carcinoma. Head Neck Pathol 2011 Jun;5(2):188-92. DOI: https://doi.org/10.1007/s12105-011-0242-6.
    7.    Gurgel CA, Freitas VS, Ramos EA, Santos JN. Sclerosing polycystic adenosis of the minor salivary gland: case report. Braz J Otorhinolaryngol 2010 Mar-Apr;76(2):272. DOI: https://doi.org/10.1590/S1808-86942010000200021.
    8.    Perottino F, Barnoud R, Ambrun A, Poupart M, Pignat JC, Merrot O. Adénose sclérosante polykystique de la parotide: diagnostic et prise en charge thérapeutique. [Article in French]. Annales Françaises d’Oto-Rhino-Laryngologie et de Pathologie Cervico-Faciale 2010 Mar;127(1):20-3. DOI: https://doi.org/10.1016/j.aforl.2010.02.005.
    9.    Kim BC, Yang DH, Kim J, Samayoa SRK, Na HY, Choi EJ, Kim HJ. Sclerosing polycystic adenosis of the parotid gland. Journal of Craniofacial Surgery 2012 Sep;23(5):451-52. DOI: https://doi.org/10.1097/SCS.0b013e318262d2a5.

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