Sialolipomas of minor salivary glands: A multi‐institutional study and literature review

Abstract

Background Sialolipoma is a rare histological variant of lipoma commonly misdiagnosed and composed of a proliferation of mature adipocytes with secondary entrapment of normal salivary gland tissue. The purpose of the present study is to report the clinicopathologic and immunohistochemical features of 10 new cases of sialolipomas in conjunction with a review of the literature. Methods A retrospective descriptive cross‐sectional study was performed. A total of 54,190 biopsy records of oral and maxillofacial lesions from four oral and maxillofacial pathology services in Brazil were analysed. All cases of lipomas were reviewed, and clinical, demographic and histopathological data were collected of all cases compatible with sialolipomas. In addition, immunohistochemistry stains (AE1/AE3, CK7, 34βE12, S‐100, HHF35, α‐SMA and Ki‐67) and a literature review based on a search of three electronic databases (PubMed, Web of Science and Scopus) were performed. Results Among all lipomas reviewed, there were 10 cases of sialolipomas. The series comprised of 7 females (70.0%) and 3 males (30.0%), with a mean age of 46.1 ± 21.5 years (range: 11‐71 years) and a 2.3:1 female‐to‐male ratio. The lower lip (n = 3, 30.0%) and tongue (n = 2, 20.0%) were the most common locations, presenting clinically as a nodule of slow growth and normal colour. Conservative surgical excision was the treatment in all cases. No recurrence was observed. Conclusion Sialolipomas are a rare histological variant of lipoma, affecting the salivary glands, mainly in the parotid gland and palate of female adults. Pathologists must recognise sialolipomas to avoid misdiagnoses with other lipomatous tumours that can affect salivary glands.

Oncocytic Lipoadenoma: Report of 3 Rare Cases Involving the Parotid Gland, Including a Synchronous Presentation With Paraganglioma of the Right Carotid Bifurcation and Literature Review

“…In addition, sialolipomas tend to exhibit multiple lobes of fat tissue, with the salivary gland elements uniformly distributed within the fatty component. 2,4 Interestingly, tumors exhibiting both characteristics of OL and sialolipoma have been illustrated by other investigators and described as "oncocytic sialolipomas." 21,34 Pusiol et al 34 reported an interesting case of a probable sialolipoma affecting the submandibular gland with a prominent oncocytic component.…”

“…In addition, sialolipomas tend to exhibit multiple lobes of fat tissue, with the salivary gland elements uniformly distributed within the fatty component. 2,4…”

“…2,14,33 Differential diagnosis also includes sialolipomas, a rare histological variant of the lipoma composed of adipocytes and normal salivary gland tissue. 4 Although epithelial/ myoepithelial elements of sialolipomas may exhibit focal oncocytic metaplasia in some cases, in general, it does not have a prominent oncocytic component such as OLs. In addition, sialolipomas tend to exhibit multiple lobes of fat tissue, with the salivary gland elements uniformly distributed within the fatty component.…”

“…However, other tumors can also exhibit oncocytic features such as pleomorphic adenoma, myoepithelioma, sialolipoma, mucoepidermoid carcinoma, and epithelial–myoepithelial carcinoma. 1,2,4-7…”

“…However, other tumors can also exhibit oncocytic features such as pleomorphic adenoma, myoepithelioma, sialolipoma, mucoepidermoid carcinoma, and epithelial-myoepithelial carcinoma. 1,2,[4][5][6][7] Recently, another oncocytic tumor affecting the salivary glands has been described and named oncocytic lipoadenoma (OL) or oncocytic adenolipoma. 2,8,9 The term oncocytic lipoadenoma, first coined in 1998 by Hirokawa et al, 8 describes a rare morphologically distinct tumor composed of oncocytes and mature adipocytes.…”