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Malignant Fibrous Dermal Tumors at a Glance
  • A group of uncommon and rare cutaneous tumors with varying degrees of malignant potential.
  • Includes dermatofibrosarcoma protuberans (DFSP), atypical fibroxanthoma (AFX), desmoids tumor, myxofibrosarcoma (MFS), undifferentiated pleomorphic sarcomas (UPS), and epithelioid sarcoma (ES).
  • Diagnosis is made by biopsy.
  • DFSP is a locally aggressive tumor with a high rate of local recurrence with rare metastases.
  • AFX is an intermediate-grade neoplasm that usually arises on sun-damaged skin in the eighth decade.
  • Desmoid tumors are slowly growing tumors arising from the muscular aponeurosis that have been associated with a history of trauma or an operation; thus, women undergoing cesarean sections are at greater risk.
  • MFS represent a spectrum of malignant myxoid tumors of fibroblastic origin that exhibit a range of clinical and histopathologic features.
  • UPS is almost never a cutaneous tumor.
  • ES is a rare, highly aggressive tumor that classically presents on the hands and fingers of young males, which can mimic nonneoplastic inflammatory lesions.

Malignant fibrohistiocytic tumors are a heterogeneous group of mesenchymal neoplasms. These neoplasms occur in the dermis and subcutaneous tissue and may cause diagnostic difficulties. This is at least in part due to the fact that these tumors are relatively rare while at the same time there is a perplexing variety of morphological types and subtypes; thus, the individual physician usually has limited experience in these tumors. By light-microscopic examination cells constituting fibrohistiocytic tumors are characterized by morphologic similarities to fibroblasts and histiocytes. Notably, the term “fibrohistiocytic” only denotes this morphologic appearance, it does not necessarily account for the histogenesis of the respective neoplasm.

The initial descriptions of these tumors were based entirely on hematoxylin and eosin (H&E) morphology and the term “fibrohistiocytic” was chosen in an attempt to provide an organizing principle and nomenclature for this group of soft tissue tumors, composed of cells resembling fibroblasts and histiocytes.

Over the last decades all scientific attempts to demonstrate true histiocytic differentiation in these tumors failed. By means of electron microscopy, immunohistochemistry (IHC), and cytogenetics, it became increasingly obvious that the term “fibrohistiocytic” is a misnomer and falsely unite a heterogeneous group of tumors, many of them are probably unrelated. This notion has been also recently endorsed by the World Health Organization by the use of the terminology “So-called Fibrohistiocytic Tumors” indicating that this term is only used descriptively.1

The symptoms that call attention to a fibrohistiocytic tumor are usually those caused by its presence and growth at its site of origin. In most cases the patient may present with an asymptomatic mass. Thus, a biopsy (either open or large-gauge core needle) is needed to obtain adequate tissue for diagnosis. Care should be taken to ensure that the biopsy does not interfere with subsequent optimal definitive surgery. Moreover, it should be kept in mind that fibrohistiocytic tumors can be very heterogeneous: the smaller the biopsy sample, the more likely it is that ...

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