Dermatofibrosarcoma Protuberans
Key Points
Dermatofibrosarcoma protuberans is a fibroblastic cutaneous sarcoma that represents the most common dermal sarcoma
It has a very low metastatic potential but has a tendency for local recurrence when incompletely resected
It typically arises within the dermis and subcutaneous fat and runs an indolent, low-grade course
Cases have been associated with tattoos and areas of previous trauma and radiation exposure
Lesions present as an asymptomatic, skin-colored to red-brown, slowly growing, indurated, superficial soft tissue plaque
The mainstay of treatment is surgical resection with negative margins
The prognosis is generally very good if the tumor is widely excised
Dermatofibrosarcoma protuberans (DFSP) is a fibroblastic cutaneous sarcoma that represents the most common dermal sarcoma.1 It generally runs an indolent course and is associated with a high cure rate when completely resected.2 The classic form of DFSP has a very low metastatic potential but has a tendency for local recurrence when incompletely resected. However, this tumor may undergo a fibrosarcomatous transformation in 5% to 15% of cases, and this is associated with an increased risk of metastases, of about 10% to 15%.3 The presence of transformed fibrosarcomatous features can often be detected in the primary tumor, but in some cases, it is identified only in relapsed tumors.3,4 DFSP was first established as a distinct disease by Darier and Ferrand in 1924.5 The term dermatofibrosarcoma protuberans was coined in 1925 by Hoffman,6 and in 1962 Taylor and Helwig emphasized its histopathologic findings.7
DFSP is an indolent, low-grade cutaneous soft tissue sarcoma that typically arises within the dermis and subcutaneous fat, and in some cases infiltrates deeper into muscle and fascia.8 Rarely, this tumor can arise within subcutaneous fat, either without involvement of the dermis or with only minimal dermal involvement.8 It represents less than 0.1% of all malignancies, less than 5% of adult soft tissue sarcomas, about 18% of all cutaneous soft tissue sarcomas,9 and fewer than 1% of all malignant tumors of the head and neck.10,11 It has an incidence of 0.8 to 4.2 cases per million persons per year.12,13
DFSP is a soft tissue sarcoma that usually originates from the dermis of the skin. It rarely metastasizes (less than 5%), but there is a high propensity for local recurrence, often associated with significant morbidity.14 The tumor can be locally aggressive when it extends into deeper subcutaneous layers.15
This tumor usually occurs in the third to sixth decades of life, but it has also been reported in infants, children, and adolescents, with pediatric patients accounting for about 6% of cases.16,17 Males are affected slightly more frequently than females (about 57%),18,19 and blacks have an incidence that is almost double that reported among Caucasians.20
DFSP occasionally exhibits fibrosarcomatous transformation (DFSP-FS), seen in 7% to 16% of cases.18,21 In these instances, it exhibits a more aggressive course, shows an increased capacity for hematogenous dissemination, and is associated with a risk of metastasis of about 10%.22,23,24,25 The main sites for DFSP-FS metastasis are the lungs, bones, soft tissue, and brain.26,27 Clinically, DFSP-FS is indistinguishable from classic DFSP and requires histopathology for differentiation.28
Etiology and Pathogenesis
The etiology of DFSP remains unknown. Cases have been associated with tattoos,29,30 and can occur in areas of previous trauma such as vaccination scars, central venous lines, and burn scars, and have been associated with tanning bed use.31,32,33,34 Postradiation DFSP has been reported in seven cases.35,36,37,38,39,40
The histogenesis of DFSP remains controversial and has been attributed to fibroblastic, myofibroblastic, and neural origins. Dominguez-Malagon et al41 presented ultrastructural evidence supporting a dendritic dermal cell origin. DFSP is characterized by the chromosomal translocation t(17;22) (q22;q13) between chromosomes 17 and 22. This translocation is present in more than 90% of DFSP and is thought to be a key factor in its pathogenesis. This leads to the fusion of the genes encoding for platelet-derived growth factor-beta polypeptide (PDGFB) and collagen type 1A1 gene (COL1A1). The resulting fusion gene upregulates PDGFB, resulting in overproduction of PDGF and leading to cellular proliferation and tumor formation.1,42
Molecular profiling in a small number of cases (five DFSP and five DFSP with FS transformation) indicated that the FS progression was sustained by a transcriptional reprogramming, paralleled by a loss of genomic material from a nontranslocated chromosome 22q, and occasional loss of the short arm of chromosome 22.22
 FIGURE 130.1 Subcutaneous nodule of dermatofibrosarcoma in the medial lower eyelid and medial canthus. (Courtesy of Drs. John Holds and Scott Fosko.) |
 FIGURE 130.2 DFS of the medial brow. (Courtesy of Dr. Jurij Bilyk.) |
 FIGURE 130.3 Surgical excision of the lesion in Figure 130.1 showing the subcutaneous location. (Courtesy of Drs. John Holds and Scott Fosko.) |
Clinical Presentation
DFSP usually presents as an asymptomatic, skin-colored to red-brown, slowly growing, indurated, superficial soft tissue plaque that eventually develops single or multiple raised violaceus nodules in early to middle adult life (Figures 130.1 and 130.2). Tumors are usually firm, and hemorrhages or cystic degeneration may be seen. A pigmented variant (known as Bednar tumor) is seen in less than 5% of cases. Necrosis is rare and suggests the possibility of high-grade transformation.43
The mean duration of symptoms before presentation is 2 to 3 years but can range from a few months to as much as 60 years.44 The most common sites of occurrence are the trunk (40%-60%), proximal extremities (20%-40%), and head and neck (10%-15%).18,45,46
Most lesions remain localized within the dermis and subcutaneous tissue (Figure 130.3), but recurrent or long-standing tumors can invade more deeply into the fascia, muscle, periosteum, and even bone. In the early growth phase, tumors are fixed to the overlying skin without involvement of deeper tissues, but later they can begin a rapid growth phase where they can infiltrate into deeper fascial planes. Rapid tumor enlargement often reflects fibrosarcomatous transformation.47
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