Spindle Cell Lipomas Arising at Atypical Locations.

Area of Science:

• Dermatopathology
• Surgical Pathology
• Oncology

Background:

• Spindle cell lipomas (SCLs) are typically found on the posterior neck, upper back, and shoulders.
• These benign lipomatous neoplasms predominantly affect older males.

Purpose of the Study:

• To investigate the occurrence of SCLs at non-classic anatomical sites.
• To characterize the clinical and pathological features of SCLs in atypical locations.

Main Methods:

• Retrospective review of archival cases of SCL.
• Analysis of tumor location, patient demographics, and immunohistochemical markers (CD34, desmin, Rb).

Main Results:

• 57 out of 439 SCL cases occurred at atypical sites (trunk, lower extremities, distal upper extremities).
• Atypical SCLs showed a near-equal sex distribution (32 males, 25 females).
• Immunohistochemistry revealed consistent CD34 positivity, frequent loss of Rb expression, and absence of CPM/MDM2 amplification.

Conclusions:

• Spindle cell lipomas can manifest in the trunk, lower extremities, and distal upper extremities.
• Unlike classic SCLs, those in atypical sites have a balanced sex distribution.
• Awareness of SCLs at non-classic sites is crucial for accurate diagnosis and to prevent misclassification.