Indian Journal of Pathology and Microbiology

: 2014  |  Volume : 57  |  Issue : 4  |  Page : 647--648

Myxoinflammatory fibroblastic sarcoma with areas resembling hemosiderotic fibrolipomatous tumor: A rare case indicating proximity between the two tumors

Bharat Rekhi, Shraddha Adamane 
 Department of Pathology, Tata Memorial Hospital, Dr E.B. Road, Parel, Mumbai, Maharashtra, India

Correspondence Address:
Dr. Bharat Rekhi
Department of Pathology, 8th Floor, Annex Building, Tata Memorial Hospital, Dr E.B. Road, Parel, Mumbai - 400 012, Maharashtra

How to cite this article:
Rekhi B, Adamane S. Myxoinflammatory fibroblastic sarcoma with areas resembling hemosiderotic fibrolipomatous tumor: A rare case indicating proximity between the two tumors.Indian J Pathol Microbiol 2014;57:647-648

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Rekhi B, Adamane S. Myxoinflammatory fibroblastic sarcoma with areas resembling hemosiderotic fibrolipomatous tumor: A rare case indicating proximity between the two tumors. Indian J Pathol Microbiol [serial online] 2014 [cited 2022 Jan 23 ];57:647-648
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Myxoinflammatory fibroblastic sarcoma (MIFS) is a unique, locally aggressive neoplasm of modified fibroblasts with proclivity for occurrence in the proximal and distal extremities (acral sites). This tumor has characteristic histopathological features and invariably a protracted clinical course. [1] Hemosiderotic fibrolipomatous tumor (HFLL) is another recently described soft tissue tumor, but with uncertain differentiation, histopathologically characterized by adipocytes, hemosiderin-laden macrophages and scattered chronic inflammatory cells. HFLL commonly occurs in distal extremities and similar to a MIFS, is characterized by a protracted clinical course. [2] Recent studies have unravelled proximity between these tumors, including presence of common cytogenetic anomaly, including a der (10) t (1; 10), and abnormalities of chromosome 3. [3],[4]

A 58-year-old gentleman presented with a slowly increasing, painless and non-mobile, visibly 'peanut-sized' swelling over his right ankle since 1 year that increased in size up to 2 cm. Ultrasonogram revealed a 6.8 6.6 2.9 cm 3 sized oval soft tissue mass. He underwent surgical excisions on two occasions, followed by radiotherapy. Paraffin blocks from the tumor were submitted to us for review. Histopathological examination showed a poorly delineated tumor exhibiting alternate nodules of myxoid areas and inflammatory cells, including lymphocytes, plasma cells, eosinophils and neutrophils. Intervening fibroblastic cells exhibited moderate to marked nuclear pleomorphism, including 'virocyte-like' intranuclear inclusions and smudgy hyperchromatic nuclei. Interspersed were fibrohistiocytic giant cells, including Langhan's type. Focal necrosis was seen. However, mitotic figures were not identified. In addition, distinct areas of adipocytic differentiation with groups and sheets of pigment histiocytes, spindly forms and inflammatory cells were also noted. Prussian blue staining highlighted hemosiderin pigment [Figure 1]a-e. Immunohistochemically, tumor cells were positive for CD34 and CD68. Ki67/ MIB1 count was approximately 2-3% in focal areas. P53 highlighted rare tumor cells [Figure 2]a-d. Diagnosis of MIFS with focal areas resembling HFLL was formed. Post excision, patient underwent radiotherapy and has been free of disease since 2 years, but is suffering from lymphedema.{Figure 1}{Figure 2}

MIFS is characterized by classical histopathological features, especially inclusion-body like nucleolus/pseudoinclusion and/or smudgy hyperchromatic nuclei. [1] The importance of correct identification of this tumor is to avoid over diagnosis of pleomorphic sarcoma of fibrohistiocytic type/malignant fibrous histiocytoma, as occurred in present case at the referring laboratory. This led to adjuvant radiotherapy that the patient was offered. At the same time, such tumors at proximal sites can be underdiagnosed as giant cell tumor of tendon sheath. [5] In view of its inflammatory component, inflammatory myofibroblastic tumor (IMT) forms an important differential of MIFS. However, unlike MIFS, IMT more commonly occurs in sites like lungs and abdomen; histopathologically lacks pleomorphic giant cells with 'virocyte-like' nuclear inclusions, pseudolipoblasts, aggregates of pigment histiocytes, features that were noted in the present case. Moreover, by immunohistochemistry, IMT displays cytoplasmic ALK positivity in 50% cases, unlike MIFS.

Recent studies have disclosed entities like hybrid myxoinflammatory fibroblastic sarcoma/hemosiderotic fibrolipomatous tumor that seem to provide further evidence for a pathogenetic link between MIFS and HFLL. [3.4] The present tumor showed distinct focal areas resembling HFLL, reinforcing morphological proximity between MIFS and HFLL. CD68 immunostaining in giant cells and CD34 positive immunostaining pointed towards fibrohistiocytic differentiation of this tumor. In their case, Elco et al.[3] observed CD34 positivity and CD68 negativity. In a recent series of 103 cases of MIFS, Laskin et al.[5] observed presence of HFLL-like areas in 4 (3.8%) tumors, indicating extreme rarity of such tumor association. They observed CD34 positivity in 50% cases and CD68 positivity in 27% cases and necrosis in 17.3% cases. Additional cases of MIFS resembling HFLL will shed more light on the proximity between these two soft tissue tumors, at least in some cases.


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