Report of two cases of recurrent scalp dermatofibrosarcoma protuberans and literature review.

Dermatofibrosarcoma protuberans (DFSP) are rare malignant skin tumor, and scalp DFSP is even lesser than 5% of all DFSP, therefore, being seldom reported. We recently treated two cases of recurrent scalp DFSPs. One was a 38-year-old male, who accept lumpectomy for the first time; however, it recurred 9 months later. We then performed a wide excision resulting in no recurrence in the subsequent 4 years. Another patient was a 26-year-old female, who accept an in situ tumorectomy for the first time, and 2 years later; the recurrent mass became 9 × 9 cm in size. We gave her another operation, but only 3 months later local recurrence appeared. For the both cases, we collected their case histories, intraoperative findings, pathologic detections, and follow-up results, all of which may help the dermatologists to extend knowledge about this rare disease. Moreover, an exhaustive review of the literature is included with emphasis on diagnosis, different diagnosis and treatments.

What was known?

Dermatofibrosarcoma protuberans is a low-grade malignant skin tumor; however, wide local excision generally could lead to a cure.

Introduction

Dermatofibrosarcoma protuberans (DFSP) is a low-grade malignant skin tumor, which most frequently affects the dermis and subcutis. It accounts for < 0.1% of all malignancies.[12] Approximately half cases of DFSP present on the trunk, then on extremities (accounting for 20-35% of cases), with the head and neck affected less commonly, in 10-15% of cases.[3] And even less than 5% of these tumors are located on the scalp.[4] Scalp DFSP generally gets more attentions because of its bad effect on patients’ appearance; however, because of its’ low incidence, DFSP of the scalp was seldom reported. In the past 4 years, we treated two cases, and both were recurrent, now we report them as follows.

Case Reports

Case 1

A 38-year-old male with a painless mass (about 4 × 3 cm) in left temporal scalp accept lumpectomy when the first admission; however, 9 months later he found the recurrence of the mass. At the second admission, the tumor mass was about 1 cm in diameter at the original location. The head magnetic resonance imaging (MRI) showed no intracranial or cranioaural infiltration [Figure 1a and b]; the tumor was retreated by wide excision with 3 cm margins, and the local skin, subcutaneous tissue, epicranial aponeurosis and skin periosteum were removed together. Partial temporal muscle was also excised [Figure 2a]. The skin defect was closed with a split-thickness skin graft [Figure 2b]. Pathological examination confirmed the diagnosis of DFSP, with positive expression of CD34 and Vimentin [Figure 3a–c]. The patient has been free of tumor for 4 years [Figure 4].

Figure 1

Magnetic resonance imaging shows a left temporal extracranial space-occupying lesion (red arrow) with T1 low signal (a) and T2 high signal (b)

Figure 2

(a) The intraoperative wide excision. (b) A split-thickness skin graft

Figure 3

Spindle cells in storiform pattern (a) Haematoxylin/eosin staining expressing CD34 (b) and Vimentin (c) (×400)

Figure 4

No recurrence 4 years after operation

Case 2

A 26-year-old female with parietal DFSP first accepted in situ tumorectomy. Two years later, the tumor recurred. Before the second operation, the tumors mass were about 9 × 9 cm in size. And on the tumor surface, blood vessels were visible, with several satellite nodules around, but without skin ulceration [Figure 5]. Computed tomography scans indicate no intracranial or cranioaural erosion [Figure 6a], and MRI showed a tumor with low signal on T1, and high signal on T2, as well as uneven post-contrast enhancement, which indicated intratumoral necrosis [Figure 6b–d]. However, because the patient refused to accept extended resection, only tumor local enucleation was performed. Intraoperatively, the tumor mass was measured to be 9 × 10 × 4.5 cm in size, with a tender texture; and the cross-section of the mass was grey or plum, with sporadic hemorrhage and necrosis [Figure 7a]. Immunohistochemistry detection [Figure 7b–d] showed CD34 (+), Vimentin (+), and Ki67 (+10-15%), but negative with smooth muscle actin (SMA) and factor XIII [Figure 8a and b]. After 3 months follow-up, local recurrence appeared.

Figure 5

The patient's scalp

Figure 6

(a) The computed tomography scans results. (b-d) The magnetic resonance imaging results

Figure 7

(a) The general appearance of tumor section. (b-d) The expressions of CD34, Vimentin and Ki67, respectively (×400)

Figure 8

The negative expressions of SMA (a) and factor XIII (b) (×400)

Discussion

DFSP is a rare soft-tissue tumor with a history of a firm, slow-growing painless cutaneous nodule. Incisional biopsy is most often performed, and the definitive diagnosis is made using histologic analysis, often with the assistance of immunohistochemical stains. Fine-needle aspiration should generally be avoided, because it often will not yield a definitive diagnosis.[5] DFSP in its classic histologic appearance on hematoxylin and eosin (H and E) staining consists of a proliferation of dermal spindle cells. The spindle cells in the deep dermis are often arranged in a storiform or cartwheel pattern. These proliferations are made up of monotonous cells with little pleomorphism and a low mitotic index.

Other than classic types, in rare cases, DFSP shows areas with high-grade fibrosarcomatous changes. When dedifferentiated areas represent more than 5% of tumor tissue, the lesion is classified as fibrosarcomatous (“high-grade”) dermatofibrosarcoma protuberans (FS-DFSP), which represents a more aggressive appearing variant of DFSP. Generally, FS-DFSP showed a high immunoreactivity for SMA compared with other subtypes, in order to exclude the possibility of our cases being FS-DFSP; we detected the expressions of SMA with immunohistochemistry staining, and our results showed that both case were SMA negative.

DFSP may at times be difficult to differentiate from other fibrous tumors, including atypical fibroxanthoma and fibrosarcoma, both of which generally have a greater degree of cellular pleomorphism and more caryomitosis than DFSP. DFSP, in particular, may be difficult to differentiate from dermatofibroma on routine H and E-stained tissue, sometimes; immunohistochemical stains are frequently employed to help differentiate the two. CD34 has been shown in multiple studies to be strongly expressed in many cases of DFSP.[6] In addition to CD34, Vimentin is often highly expressed in DFSP. In contrast, the coagulation factor XIIIa is generally not expressed in DFSP but is strongly expressed in dermatofibroma. These are in line with the two cases of ours.

Imaging features are often suggestive, generally, on MRI, T1 low signal and T2 high signal were consistent features with enhancement seen after gadolinium, which sometimes is inhomogeneous, indicating hemorrhage or necrosis in a large tumor mass. Although the imaging features are not specific; it still can aid in clearly delineating the anatomic structures involved and rule out invasion of deep structures.[7]

Surgical resection is the preferred treatment for DFSP. Before operation, the chest X-ray and ultrasonography detections are suggested to exclude of metastasis or some other possible accompanying tumors, though metastasis of DFSP was seldom reported. For both of our cases, we got no especially positive results. The recurrence rates after operation vary from 10% to 60%.[3] However, the use of wide local excision could lead to a much lower rate of tumor recurrence,[8] where the term “wide local excision” is not well defined in the literature. Most authors consider margins of between 2 and 4 cm to be wide. For the first case, the surgical margin was 3 cm around the lesion, and he has no recurrence after 4 years’ of follow-up. In addition to wide local excision, Mohs micrographic surgery has emerged as an attractive treatment option.[9] DFSP is radiosensitive, and radiation therapy is usually used in the setting of extremely large or recurrent tumors.[10] In addition, imatinib chemotherapy is also considered to be effective in cases of DFSP recurrence after resection or in cases that are deemed unresectable.