Encyclopedia of Pathology

Living Edition
| Editors: J.H.J.M. van Krieken

Dermatofibrosarcoma Protuberans, Genitourinary Tract

  • Raffaele Gaeta
  • Alessandro FranchiEmail author
Living reference work entry
DOI: https://doi.org/10.1007/978-3-319-28845-1_5006-1

Synonyms

Definition

Locally aggressive spindle cell fibroblastic tumor of intermediate malignancy.

Clinical Features

  • Incidence

    Dermatofibrosarcoma protuberans (DFSP) is a rare neoplasm (estimated incidence between 0.8 and 5 cases per one million population per year), but represents the most frequent superficially located sarcoma

  • Age

    Usually adults between 20 and 50 years, but can rarely occurs in infants and children

  • Sex

    Slight male predominance

  • Site

    The trunk, the proximal extremities, and head and neck region are the most common involved sites. To the best of our knowledge, in male genital organ DFSP has been described in scrotum (1 case) and penis (6 cases). Only one testicular metastasis is reported in English literature.

  • Treatment

    Wide surgical resection with excision of subcutaneous fat (2–3 cm margins) in order to prevent recurrence. Imatinib therapy (tyrosine kinase inhibitor) is the gold standard for treatment of inoperable, metastatic, or recurrent DFSP.

  • Outcome

    DFSP has an extremely high tendency for local recurrence after a limited resection. Only rare cases of metastasis in organs and regional lymph nodes have been reported (<0,5%). Progression to fibrosarcoma can rarely occur.

Macroscopy

Nodular, polypoid, or plaque-like neoplasm centered in dermis. The size is extremely variable (mean size 5 cm) and the color is generally gray-white, but may appear brown or black if melanocytes are present. Hemorrhage and necrosis are rarely seen.

Microscopy

DFSP appears as a highly cellular sarcoma with storiform pattern (cells radiating in spokes at right angles around a central point) that infiltrates deeply the dermis into subcutis and entraps fat cells to form a characteristic honeycomb pattern (Fig. 1). Cells are generally uniform and spindle with scant eosinophilic cytoplasm and plump or elongated nuclei. Mitotic figures are <5 per 10 HPF, but atypical ones are not observed. Only mild pleomorphism and focal atypia are present. No giant cells or other inflammatory cells are reported. Collagen is usually thin with small vessels.
Fig. 1

Dermatofibrosarcoma protuberans consists of a uniform population of spindle cells arranged in a storiform pattern and infiltrating fat

Most observed variants: myxoid, atrophic, granular, sclerosing, and pigmented (Bednar’s tumor, rich in pigmented melanocytic cells).

Immunophenotype

Positive: CD34 (strong and consistently in 95%), vimentin, actin (focal), and CD99 (can be weakly positive).

Negative: S-100 (except in Bednar variant), HMB-45, Factor XIIIa (usually), keratin, EMA, desmin, and CD117.

Molecular Features

DFSP presents a t(17;22)(q21;q13) translocation or a supernumerary ring chromosome derived from the translocation r(17;22). The translocation results in the fusion of exon 2 of PDGFB to various exons of the COL1A1 gene related to collagen type 1 alpha 1 gene and platelet-derived growth factor beta chain.

Differential Diagnosis

Dermatofibroma is also a storiform lesion, but it is noninfiltrative. Moreover, it is less cellular than DFSP and shows polymorphous cellular infiltrate. Factor XIIIa is positive and CD34 negative. Pleomorphic undifferentiated sarcoma and atypical fibroxanthoma presents also a storiform pattern, but also moderate to severe cellular pleomorphism and nuclear atypia.

The pigmented variant (Bednar’s tumor) must be distinguished from desmoplastic melanoma which, however, lacks storiform pattern, displaces or destroys fat, shows dense collagenous stroma, and is CD34 negative and S-100 and SOX10 positive.

References and Further Reading

  1. Abdulfatah, E., Chaudhry, R., Bandyopadhyay, S., & Qureshi, F. (2016). Myxoid dermatofibrosarcoma protruberans of the scrotum: A rare diagnosis in an unreported location. Human Pathology: Case Reports., 6, 40–44.Google Scholar
  2. Chryssogonidis, I. A., Vorkas, G., Papadopoulos, C., & Lytras, C. (2002). Testicular metastasis of dermatofibrosarcoma protuberans: A case report (an ultrasonography approach). Archive of Oncology, 10(1), 33–34.CrossRefGoogle Scholar
  3. Patel, K. U., Szabo, S. S., Hernandez, V. S., Prieto, V. G., Abruzzo, L. V., Lazar, A. J., & López-Terrada, D. (2008). Dermatofibrosarcoma protuberans COL1A1-PDGFB fusion is identified in virtually all dermatofibrosarcoma protuberans cases when investigated by newly developed multiplex reverse transcription polymerase chain reaction and fluorescence in situ hybridization assays. Human Pathology, 39(2), 184–193.CrossRefGoogle Scholar
  4. Peard, L., Cost, N. G., & Saltzman, A. F. (2018). Dermatofibrosarcoma protuberans in a male infant. Urology. pii: S0090-4295(18)31135-X.  https://doi.org/10.1016/j.urology.2018.08.050. [Epub ahead of print]

Copyright information

© Springer Nature Switzerland AG 2019

Authors and Affiliations

  1. 1.Department of Translational Research and of New Technologies in Medicine and SurgeryUniversity of Pisa, ItalyPisaItaly