Dermatofibrosarcoma Protuberans: Pathological and Imaging Review Bilal Mujtaba, MD, Felicia Wang, Ahmed Taher, MD, Rizwan Aslam, MD, John E. Madewell, MD, Rosario Spear, Sameh Nassar, MD* Department of Diagnostic Radiology, University of Texas MD Anderson Cancer Center, Houston, TX ABSTRACT Dermatofibrosarcoma protuberans (DFSP) is a rare, low-to-intermediate grade sarcoma that typically arises in the dermis and infiltrates subcutaneous tissue. Due to superficial appearance of DFSP, imaging techniques are not always utilized. However, they may be useful in large or atypical cases. The standard treat- ment for DFSP is excision of the lesion. In this article, we review the role of different imaging modalities in the assessment and management of DFSP. © 2020 Elsevier Inc. All rights reserved. Introduction Soft tissue sarcomas are a rare group of tumors that accounts for less than 1% of all malignant tumors. 1 Dermatofibrosarcoma protuberans (DFSP) is a rare soft tissue sarcoma of the skin. This fibroblastic tumor was first named by Hoffman in 1925 and is generally considered a low to intermediate grade sarcoma. 2,3 The lesion typically begins in the der- mis but also has a propensity for infiltrating the underlying tissues. 4,5 DFSP is known to have a high rate of local recurrence and a low ten- dency to metastasize. 6 The imaging features of DFSP are nonspecific, but may assist with the assessment and diagnosis of the lesion. 6,7 A defini- tive diagnosis of DFSP is typically made with biopsy in conjunction with histopathological and immunohistochemistry analysis. 8,9 Incidence Dermatofibrosarcoma protuberans represents about 0.1% of all malignancies and 1.8%-6% of all soft tissue sarcomas. 7,10, 11 The estimated incidence of DFSP is approximately 0.8-5 cases per million persons per year. 1, 9,10 While DFSP may occur in all age groups, it is most commonly found between the second and fifth decades of life, peaking around 40- 50 with rates declining thereafter. 1, 3,7 A potential male predominance has been both reported and disputed in the literature, with more recent reports indicating an equal distribution. 11-13 Dermatofibrosarcoma pro- tuberans has been found to occur more frequently in blacks than whites, with incidence rates around 1.5-2 times greater in blacks. 1,13 Presentation Initially, the tumor typically presents as an indurate, cutaneous nodule or plaque that is fixed to the superficial skin but moves freely over deeper layers. 11,12 The lesion has been described to range from pink-violet to red-brown and skin toned in color. 9,11 The size of DFSP is generally small, less than 5 cm. 14 While the tumor often grows slowly over a long period of time, periods of rapid growth have been reported and the tumor can reach 20 cm or greater in size. 12,15 As the disease advances the tumor may also infiltrates deeper tissue layers and demonstrates nodular growth. 4 Owing to the indolent growth pattern, the tumor may proceed undiagnosed for many years. 9 The most common location of DFSP is the trunk, with the majority of studies reporting around half of lesions presenting on the trunk. The lower and upper extremities followed by the head and neck region are the next most common sites of DFSP. 10,11,15 DFSP of the breast and vulva have also been observed. 13,16,17 Etiology The exact etiology of DFSP is not fully understood. Prior trauma to the affected region has been suggested, but is likely coincidental. 2,18,19 Genetic factors play an important role in the pathogenesis of DFSP. The chromosomal translocation t(17;22)(q22;q13) is present in approxi- mately 90% of cases. 7,8 This results in the fusion of the collagen, type 1, alpha 1 gene (COL1A1) to the platelet-derived growth factor b-chain gene (PDGFB). 6 This COL1A1-PDGFB fusion transcript leads to the con- tinuous activation of the PDGFB receptor, promoting the proliferation of DFSP tumor cells. 11,20 Inhibition of the PDGFB receptor tyrosine kinase pathway was shown to disrupt tumor growth, suggesting its impor- tance in tumorigenesis. 21 Pathology Grossly DFSP typically appears as an oval shaped mass that is often multinodular. 22 The excised lesion has been described as rub- bery to firm, fibrous tissue that is yellow to gray-white in color. 18 Hemorrhagic or cystic areas have been reported. 19 Microscopically, DFSP is characterized by a uniform population of spindle-shaped fibroblasts arranged in a storiform “cartwheel” pattern along with a Conflict of Competing Interest: None. *Reprint requests: Sameh Nassar MD, Department of Diagnostic Radiology, Univer- sity of Texas MD Anderson Cancer Center, Houston, TX 77030 E-mail address: SMNassar@mdanderson.org (S. Nassar). https://doi.org/10.1067/j.cpradiol.2020.05.011 0363-0188/© 2020 Elsevier Inc. All rights reserved. ARTICLE IN PRESS Current Problems in Diagnostic Radiology 000 (2020) 1À5 Current Problems in Diagnostic Radiology journal homepage: www.cpdrjournal.com