Haemosiderotic fibrolipomatous tumor

Last revised by Joachim Feger on 22 Oct 2022

Haemosiderotic fibrolipomatous tumors or haemosiderotic fibrohistiocytic lipomatous lesions are locally aggressive soft tissue tumors of uncertain differentiation.

Haemosiderotic fibrolipomatous tumors are rare with an estimated incidence of less than 0.2% of all benign lipomatous lesions. They have been described in all ages, but are predominantly seen in women in their 5th and 6th decades of life 1-3.

Haemosiderotic fibrolipomatous tumors are diagnosed based on typical histological and molecular pathological features.

Diagnostic criteria according to the WHO classification of soft tissue tumors (blue book) 1:

  • mature adipose tissue intermingled with bland hemosiderin-containing spindle cells and macrophages

The following criterion is desirable:

  • TGFBR3 and/or OGA rearrangement

Clinically the tumors commonly manifest as a slow-growing subcutaneous mass sometimes associated with pain. Less often they occur in the deep soft tissues 1

Haemosiderotic fibrolipomatous tumors are unencapsulated neoplasms consisting of adipocytes and spindle cells with intracytoplasmatic hemosiderin inclusions 1.

The etiology of haemosiderotic fibrolipomatous tumors is unknown 1.

Haemosiderotic fibrolipomatous tumors are predominantly found in the following locations 1:

  • dorsum of the foot and ankle region
  • hands
  • calf and thighs
  • cheeks

Macroscopically haemosiderotic fibrolipomatous tumors are poorly delineated friable lesions with a dark yellow to brown color. They can be quite sizable on detection with an average of 7-8 cm 1-3

Microscopically haemosiderotic fibrolipomatous tumors consist of lobules of mature adipocytic cells mixed with fascicles of hemosiderin-containing fibroblastic spindle cells and hemosiderin-laden macrophages and giant cells. Beyond that, there are sometimes features resembling pleomorphic hyalinizing angiectatic tumors as ectatic partially thrombosed vessels with perivascular hyalinisation. There is usually no necrosis and a low mitotic activity 1,3.

On immunohistochemistry stains, haemosiderotic fibrolipomatous tumors usually express CD34 and calponin 1.

Similar to pleomorphic hyalinizing angiectatic tumors of soft parts, haemosiderotic fibrolipomatous tumors are associated with rearrangements of the TGFBR3 and/or OGA genes 1.

On MRI haemosiderotic fibrolipomatous tumors have been described as an ill-defined complex predominantly fat-intense mass with intermixed lipomatous and fibrous elements and with hemosiderin deposits 1-4, often displaying a blooming phenomenon on gradient echo sequences 5.

  • T1: heterogeneous in up to 2/3 iso- to hypointense to muscle 5
  • T2: heterogeneously hyperintense
  • STIR/PDFS: heterogeneously hypointense
  • T1C+ (Gd): heterogeneous enhancement

The radiological report should include a description of the following:

  • form, location and size
  • tumor margins and transition zone
  • relations to the muscular fascia
  • relation to adjacent neurovascular structures
  • relations to bones

Treatment includes surgical excision. Local recurrence occurs in about 30-50% of the resected lesions in particular upon incomplete excision. The tumor itself does not metastasize but transformations to myxoid sarcoma have been described 1-3.

Haemosiderotic fibrolipomatous tumors have been first reported by the American pathologists, Cristina Marshall-Taylor and Julie C. Fanburg-Smith in 2000 2,3,6.

Tumors or conditions which can mimic the presentation and/or appearance of haemosiderotic fibrolipomatous tumors include lipomasatypical lipomatous tumors and pleomorphic hyalinizing angiectatic tumors of soft parts 2,3.

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