Spindle cell / pleomorphic lipoma

Definition

A benign tumour typically occurring on the neck or back of elderly males, consisting of spindle cells, floret giant cells and ropey collagen.

Clinical features

Most tumour occur on the shoulders or posterior neck; head and upper arms are less common sites. 90% of cases occur in males, usually over 55 years of age.

Macroscopic appearances

Tumours vary from yellow to white, often firmer than typical lipomas, but may be gelatinous.

Histopathology

This tumour forms a spectrum:

spindle cell lipomas are composed of bland spindle cells in parallel arrays between adipocytes, with thick ropey collagen.
pleomorphic lipoma are composed of small spindle and round cells with hyperchromatic nuclei, and multinucleate cells with a ring or floret of nuclei.

Mast cells may be abundant and there may be a lymphoplasmacytic infiltrate.

Immunohistochemistry

CD34 positive in the spindle cells
S-100 rarely positive in the spindle cells.
bcl-2 positive

Differential diagnosis

neurofibroma: S-100 positive
dermatofibrosarcoma protuberans: also CD34 positive
solitary fibrous tumour: also CD34 and bcl-2 positive
angiolipoma

Management

Local excision is sufficient.

References

World Health Organization Classification of Tumours, Tumours of Soft Tissues and Bone, IARC Press 2002.

Diagnostic Immunohistochemistry edited by Professor D. J. Dabbs, page 74

This page last revised 29.6.2004.