Soft tissue

Adipose tissue tumors

Other benign lesions

Lipoblastoma / lipoblastomatosis



Last author update: 20 December 2022
Last staff update: 20 December 2022

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PubMed Search: Lipoblastoma / lipoblastomatosis

Jamshid Abdul-Ghafar, M.D., Ph.D.
Nasir Ud Din, M.B.B.S.
Page views in 2022: 10,808
Page views in 2023 to date: 909
Cite this page: Abdul-Ghafar J, Haidari M, Ud Din N. Lipoblastoma / lipoblastomatosis. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/softtissueadiposelipoblastoma.html. Accessed February 3rd, 2023.
Definition / general
  • Benign, rapidly growing neoplasm composed of embryonal white fat with variable degrees of myxoid changes (Mod Pathol 2021;34:584, J Clin Med 2022;11:1938)
  • Occurs predominantly in infancy, early childhood and very rarely in adulthood (J Clin Med 2022;11:1938)
  • Lipoblastoma: superficial, localized, well circumscribed; complete excision easy; common type
  • Lipoblastomatosis: deep, diffuse, irregular borders; complete excision difficult; rare type (J Clin Med 2022;11:1938)
Essential features
  • Benign, rapidly growing neoplasm that is commonly superficial and well defined
  • 75 - 90% are seen before the age of 3 years, with male predilection (M:F = 2.8:1)
  • Mostly occurs in trunk and extremities
  • Lobular architecture with intersecting fibrovascular septa, myxoid changes and a spectrum of fat cell maturation
  • Positive stains are S100, CD34 (adipocytes and vascular network), desmin (mesenchymal cells)
Terminology
  • Lipoblastoma: well circumscribed and superficial (J Clin Med 2022;11:1938)
  • Lipoblastomatosis: deep seated with ill defined borders (J Clin Med 2022;11:1938)
  • Not recommended: fetal lipoma, fetal fat tumor, fetocellular lipoma, embryonal lipoma, congenital lipomatoid tumor, lipoblastic tumor of childhood
ICD coding
  • ICD-O: 8881/0 - lipoblastomatosis
  • ICD-10: D17.9 - benign lipomatous neoplasm, unspecified
  • ICD-11: 2E80.1 & XH8L55 - lipoblastoma / lipoblastomatosis
Epidemiology
Sites
Pathophysiology
  • Exhibits pseudodiploid or hyperdiploid karyotypes combined with structural alteration of 8q11-q13, which leads to PLAG1 rearrangement (J Clin Med 2022;11:1938)
  • Numerical change in one or more extra copies of chromosome 8, with or without concurrent rearrangement of 8q11-q13 (J Clin Med 2022;11:1938)
Etiology
Clinical features
Diagnosis
Radiology description
Radiology images

Contributed by Nasir Ud Din, M.B.B.S.
Lipomatous lesion with septations

Lipomatous lesion with septations



Images hosted on other servers:
Circumscribed, lobulated hyperechoic mass

Circumscribed, lobulated hyperechoic mass

Localized mass of soft tissue, without calcification

Localized mass of soft tissue, without calcification

T1 fat saturation (MRI)

T1 fat saturation (MRI)

Cervical mass, greasy density

Cervical mass, greasy density

Prognostic factors
Case reports
Treatment
Clinical images

Images hosted on other servers:
Right lower leg mass

Right lower leg mass

Intraoperative aspect of lipoblastoma

Intraoperative aspect of lipoblastoma

Gross description
Gross images

Contributed by Nasir Ud Din, M.B.B.S.
Gross appearance

Round mass

Cut surface

Cut surface

Gross appearance

Multilobulated mass

Microscopic (histologic) description
Microscopic (histologic) images

Contributed by Nasir Ud Din, M.B.B.S.
Lobulation Lobulation

Lobulation

Vasculature

Vasculature

Myxoid background Myxoid background

Myxoid background

Lipoblasts in various stages

Lipoblasts in various stages


Lipoblasts and mesenchymal cells

Lipoblasts and mesenchymal cells

Septation

Septation

Zonation

Zonation

Primitive mesenchymal cells

Primitive mesenchymal cells

Desmin IHC stain

Desmin IHC stain

CD34 IHC stain

CD34 IHC stain

Virtual slides

Images hosted on other servers:
Lipoblastoma / lipoblastomatosis

Lipoblastoma / lipoblastomatosis

Cytology description
Cytology images

Images hosted on other servers:
Mature adipocytes and lipoblasts

Mature adipocytes and lipoblasts

Myxoid stromal with capillaries

Myxoid stromal with capillaries

Univacuolated and multivacuolated lipoblasts

Univacuolated and multivacuolated lipoblasts

Positive stains
Negative stains
Molecular / cytogenetics description
  • Clonal rearrangements involving chromosomal region 8q11 > q13 (8q12) is the hallmark (BMC Res Notes 2018;11:42)
  • Oncogene PLAG1 (pleomorphic adenoma gene 1) is located on band 8q12 (BMC Res Notes 2018;11:42)
  • Other rare fusion partners of PLAG1 are COL1A2 (7q21.3), HAS2 (8q24.13), RAD51B (14q24.1), COL3A1 (2q32.2), RAB2A (8q12.1-q12.2) and BOC (3q13.2) (Mod Pathol 2021;34:584)
  • Novel reported fusions are HNRNPC::PLAG1, SRSF3::PLAG1, PCMTD1::PLAG1, YWHAZ::PLAG1, CTDSP2::PLAG1 and PPP2R2A (Mod Pathol 2021;34:584)
Molecular / cytogenetics images

Images hosted on other servers:
PLAG1 RNA expression

PLAG1 RNA expression

Molecular confirmation of fusions

Molecular confirmation of fusions

FISH / CISH of PLAG1 gene FISH / CISH of PLAG1 gene

FISH / CISH of PLAG1 gene

Videos

Lipoblastoma histopathology

Sample pathology report
  • Soft tissue, thigh, left, excisional biopsy:
    • Benign adipocytic neoplasm with features favoring lipoblastoma (see comment)
    • Tumor size: 7 x 6 x 4 cm
    • Margins are free of tumor
    • Comment: Histological examination shows an adipocytic neoplasm with a lobular architecture by intersecting fibrous septa and zonation along with myxoid areas. A spectrum of fat cell maturation, from primitive stellate to spindled mesenchymal cells, multivacuolated lipoblasts to mature fat cells are seen. Immunohistochemically, the tumor cells are showing positivity for S100 and CD34 and are negative for MDM2, CKD4 and p16. This constellation of morphological and immunohistochemical features strongly supports the diagnosis of lipoblastoma. This is a benign, rapidly growing soft tissue neoplasm prone to recur unless completely excised.
Differential diagnosis
Board review style question #1

A 12 month old boy presents with a large, painless mass at lateral part of the left thigh. Excisional biopsy shows a well defined lobulated mass with fibrovascular septa, myxoid areas, aggregates of spindle cells and a mixture of mature and immature adipocytes. The adipocytic cells are positive for CD34 and CD56. The desmin is positive in spindle cells. The tumor cells are negative for MDM2 and p16. Which of the following is true regarding the above scenario?

  1. Adipocytic tumor with low malignant potential
  2. Findings are compatible with myxoid liposarcoma
  3. Radiological examinations are the main diagnostic tool
  4. The tumor cells are also positive for CKD4 IHC stain
  5. The tumor mainly exhibits PLAG1 rearrangement
Board review style answer #1
E. The tumor mainly exhibits PLAG1 rearrangement

Comment Here

Reference: Lipoblastoma / lipoblastomatosis
Board review style question #2
Which of the following is true about lipoblastoma / lipoblastomatosis?

  1. It is a highly infiltrative lesion, which leads the majority to recur
  2. It is common in women and complete resection is the treatment of choice
  3. It is the most common benign neoplasm with no chance of recurrence
  4. It usually appears as a superficial, round, lobulated mass with male predilection
  5. Negative CD34 IHC stain confirms the diagnosis of lipoblastoma
Board review style answer #2
D. It usually appears as a superficial, round, lobulated mass with male predilection

Comment Here

Reference: Lipoblastoma / lipoblastomatosis
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