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lipomatous hemangiopericytoma

Monday 27 April 2009

The so-called lipomatous hemangiopericytoma is regarded as representing a fat-forming variant of solitary fibrous tumour.

The so-called lipomatous hemangiopericytoma is a soft tissue tumor composed of mature adipocytes and hemangiopericytomatous areas, for which the term "lipomatous hemangiopericytoma" has been proposed.

The tumors occurred in adults and were located in the sinonasal area, the soft tissue of the shoulder, and the retroperitoneum.

The tumors ranged in size from 4 to 10 cm in greatest diameter and grossly were solid and ranged from tan to yellow.

Histologically, they were composed of a variable admixture of benign lipomatous and hemangiopericytomatous components.

Immunohistochemically, they stained with antibodies to vimentin and not to alpha-smooth-muscle actin, muscle-specific actin, desmin, S-100 protein, glial fibrillary acidic protein, epithelial membrane antigen, or keratin.

Ultrastructurally, the cells constituting the hemangiopericytomatous areas had the features of pericytes, and no lipoblasts or transitional forms between lipocytes and pericytes were found.

The histologic differential diagnosis of this neoplasm includes spindle-cell lipoma, angiolipoma, liposarcomas, tumors showing smooth muscle and adipocytic differentiation, and hemangiopericytoma infiltrating fat.

References

- The evolving classification of soft tissue tumours: an update based on the new WHO classification. Fletcher CD. Histopathology. 2006 Jan;48(1):3-12. PMID: 16359532

- Lipomatous hemangiopericytoma. A histologic, ultrastructural and immunohistochemical study of a unique variant of hemangiopericytoma. Nielsen GP, Dickersin GR, Provenzal JM, Rosenberg AE. Am J Surg Pathol. 1995 Jul;19(7):748-56. PMID: 7793472