Abstract
Spindle cell / pleomorphic lipoma is a relatively rare mesenchymal adipocytic tumor occurring typically in subcutaneous fat tissue in the posterior neck region in middle aged and elderly male. Microscopically, the tumor is usually well-circumscribed consisting of spindle shaped cells with myxoid stroma and variable amount of adult fat tissue.
Entrapped collagen fibers and mast cells are constant finding. The lesion is characterized by positive CD34 immunohistochemistry.
The tumor belongs to a family with chromosomes 13 and/or 16 deletion and loss of tumor suppressor gene RB1. Several histological variants including "fat-poor" spindle cell lipoma with minimal or absent fat cells may rarely occur.
In this article we report a case of elderly man with a voluminous posterior neck tumor diagnosed as a fat-poor spindle cell lipoma based on histological examination, CD34-positivity and loss of Rb1 expression shown by immunohistochemistry. The diagnosis was confirmed by a molecular proof of RB1 deletion.
The paper discusses a wide differential diagnosis of spindle cell myxoid CD34+ mesenchymal tumors.