Haemosiderotic Fibrolipomatous tumour

Haemosiderotic Fibrolipomatous tumour, Haemosiderotic Fibrohistiocytic lipomatous tumour

Epidemiology

Patients are in the fifth to seventh decade of life, rarely reported in children3. There is a female preponderance. There is often a history of previous trauma to the site.

Clinical features

Tumours are most often found in the foot (often on the dorsal surface) or ankle, occasionally in the hand3.

Macroscopic appearances

The tumours are dark yellow-brown,sometimes with fatty or mucoid foci. Margins are often ill-defined3.

Histopathology

The lesions are subcutaneous. They consist of a nodules of fatty tissue separated by septa of plump spindle cells along with an inflammatory component and abundant haemosiderin, predominantly within macrophages. The adipocytes do not show atypia. There may be focal fat necrosis. The spindle cells may sometimes also form nodules. They have a low mitotic rate (<1/10HPF). At least focally, the spindle cells permeate the fat in a honeycomb fashion. Most cases include a few osteoclast-like giant cells within the spindle cell areas. A case has been reported with floret-type giant cells within the fat3. There may be focal calcification, psammoma like or in the form of metaplastic ossification3.

Immunohistochemistry

		spindle cells
	lysozyme	1/21
	CD68	3/31, 0/103
	Vimentin	2/21
	CD34	3/31, 7/93
	Calponin	2/21
	S100	0/51, 0/103
	HMB45	0/31
	Desmin	0/51, 0/103
	EMA	0/21
	AE1/AE3	0/21
	SMA	0/51, 0/103
	HHF35	0/51
	Caldesmon	0/31

Cytogenetics

There is most commonly a translocation between chromosomes 1p22 and 10q24 along with aberrations of chromosome2.

Differential diagnosis

There may be overlap with myxoinflammatory fibroblastic sarcoma and pleomorphic hyalinizing angiectatic tumour3

fibromatosis
nodular fasciitis
pseudosarcomatous fasciitis
fibrous histiocytoma
dermatofibrosarcoma protuberans
plexiform fibrohistiocytic tumour: more common on the upper limb; the fatty component is entrapped and peripheral; the spindle cell component is positive for SMA;
traumatized lipoma
fat necrosis
spindle cell lipoma; typically occurs on the upper back / neck and is circumscribed
atypical lipomatous tumour / well-differentiated liposarcoma, particularly the spindle cell variant: adipocytes are pleomorphic with hyperchromatic stromal cells and lipoblasts
myxoid liposarcoma
giant cell tumour of soft tissue; also occurs on extremities; there is haemosiderin deposition; an adipocytic component is lacking; the mononuclear cells are positive for CD68, SMA, rarely for S100 and cytokeratins.
in children:

lipofibromatosis; occurs on the extremities within the subcutis, often poorly circumscribed; the spindle cells are more primitive; haemosiderin deposition is limited; giant cells are absent.
fibrous hamartoma of infancy

Management

Surgical excision

Prognosis

Local recurrences are common but metastases have not been reported.

References

1 Marshall-Taylor C, Fanburg-Smith JC. Hemosiderotic fibrohistiocytic lipomatous lesion: ten cases of a previously undescribed fatty lesion of the foot/ankle. Mod Pathol. 2000 Nov;13(11):1192-9.

2 Elco CP, Marino-Enriquez A, Abraham JA, Dal Cin P, Hornick JL. Hybrid myxoinflammatory fibroblastic sarcoma/hemosiderotic fibrolipomatous tumor: report of a case providing further evidence for a pathogenetic link. Am J Surg Pathol. 2010 Nov;34(11):1723-7.

3 Browne TJ, Fletcher CD. Haemosiderotic fibrolipomatous tumour (so-called haemosiderotic fibrohistiocytic lipomatous tumour): analysis of 13 new cases in support of a distinct entity. Histopathology. 2006 Mar;48(4):453-61.