Differentiation of Oral Spindle Cell and Pleomorphic Lipomas From Their Mimics via Retinoblastoma Status Through Immunohistochemistry and Fluorescence In Situ Hybridization

Oral spindle cell/pleomorphic lipomas frequently exhibit prominent collagenous stroma, which results in low-fat and fibrous variants that require careful differentiation from fibrous lipomas or non-adipocytic tumors. Given the diverse histological findings, meticulous diagnosis of rare spindle cell lipoma variants and other lipomas in daily surgical pathology is essential. Specifically, it should apply CD34 and retinoblastoma protein immunohistochemistry, as well as RB1 FISH when necessary.