Lipoblasts in spindle cell and pleomorphic lipomas: a close scrutiny

Area of Science:

• Pathology
• Oncology
• Dermatology

Background:

• Spindle cell lipomas (SCL) and pleomorphic lipomas (PL) are benign soft tissue tumors.
• The presence of lipoblasts (LPB) in SCL and PL has not been extensively studied.
• Accurate diagnosis is essential to differentiate these tumors from liposarcoma.

Purpose of the Study:

• To investigate the presence and frequency of lipoblasts (LPB) in a validated cohort of SCL and PL.
• To characterize the histological and immunohistochemical features of LPB-positive SCL and PL.
• To assess the diagnostic implications of LPB in SCL and PL.

Main Methods:

• Histological review of 91 SCL and 38 PL cases.
• Immunohistochemical staining for CD34 and retinoblastoma (Rb) protein.
• Fluorescence in situ hybridization for MDM2, CDK4 amplifications, and FUS gene rearrangements in LPB-positive cases.

Main Results:

• Lipoblasts (LPB) were identified in 41% of SCL (37/91) and 66% of PL (25/38) cases.
• CD34 was expressed in all cases; Rb protein was consistently absent.
• Molecular genetic findings supported the diagnosis of SCL/PL in LPB-positive cases.

Conclusions:

• Lipoblasts (LPB) are a frequent finding in both spindle cell lipomas (SCL) and pleomorphic lipomas (PL).
• The presence of LPB can be variable, ranging from inconspicuous to prominent.
• Recognizing LPB in SCL and PL is critical to avoid misdiagnosis as liposarcoma.