Salivary glands
Other tumors
Lipoma / sialolipoma


Topic Completed: 1 September 2012

Minor changes: 17 March 2020

Copyright: 2003-2020, PathologyOutlines.com, Inc.

PubMed Search: Lipoma[TI] OR sialolipoma[TI] salivary

Adriana Handra-Luca, M.D.
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Cite this page: Handra-Luca A. Lipoma / sialolipoma. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/salivaryglandslipoma.html. Accessed June 1st, 2020.
Definition / general
  • Lipoma:
  • Sialolipoma:
    • Uncommon lipoma variant composed of mature adipose tissue mixed with acinar, ductal, basal and myoepithelial cells of normal salivary gland
    • First described in 2001 by Nagao (Histopathology 2001;38:30)
  • Lipoadenoma:
    • Slow growing tumor with glandular structures with sertoliform features and adipose tissue; oncocytic and sebaceous differentiation
    • Initially described by Yau in 1997 (Mod Pathol 1997;10:242)
Clinical features
  • Lipoma:
    • 3% of parotid tumors - #2 most common benign mesenchymal neoplasms of major salivary glands (#1 is schwannoma)
    • Often incidental (Rev Stomatol Chir Maxillofac 1988;89:117)
    • Ages 40+, usually men, occasionally children
  • Sialolipoma:
    • Mean age 61 years but wide age range at presentation
    • Female gender predominance for minor salivary gland location
    • Parotid and submandibular glands, hard and soft palate
    • May be due to entrapment of salivary gland elements by lipoma
    • Benign behavior, no recurrences reported
Case reports
Gross description
  • Well circumscribed, resembles lipoma at other sites
  • Median 2 cm (range, 1 - 4 cm)
Gross images

Case #49

Well circumscribed tumor



Images hosted on other servers:

Parotid sialoangiolipoma

Microscopic (histologic) description
  • Lipoma: bland appearing adipose tissue; osteolipoma or angiolipoma variants exist
  • Lipoadenoma: mature adipose cells (> 90% mass) and proliferated glandular tissue (sharply demarcated, duct - acinar units or proliferated glands, may resemble sertoliform tubules), oncocytic change, sebaceous differentiation, squamous metaplasia
  • Sialolipoma:
    • Mature adipose tissue mixed with acinar, ductal, basal and myoepithelial cells of normal salivary gland
    • Also duct ectasia with fibrosis, prominent lymphoid infiltrates with nodular aggregates in stroma, oncocytic changes, sebaceous differentiation
    • Vascular variant is sialoangiolipoma
Microscopic (histologic) images

Case #49

Peripheral
lipomatous tissue
with central salivary
gland elements

Lipoma-like areas

Acini and dilated ducts


Ducts with fibrosis of wall infiltrated by lymphocytes



Images hosted on other servers:

Spindle cell lipoma of parotid gland

Lower lip tumor

Submandibular sialoangiolipoma

Parotid sialoangiolipoma


Pleomorphic lipoma with classic floret-like cells

Chondroid lipoma
of lip has chondroid
and lipomatous
features

Oncocytic lipoadenoma of parotid

Cytology description
Cytology images

Images hosted on other servers:

Spindle cell lipoma:
bland spindle cells
with myxoid change
and fat, CD34+

Immunohistochemistry
Molecular / cytogenetics description
  • t(12,14) / HMGA rearrangements
Differential diagnosis
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