Dermatofibrosarcoma Protuberans of the Scalp: A Relatively unusual Site of Occurrence

Keywords

Dermatofibrosarcoma Protruberans; Scalp; IMATINIB.

Introduction

Dermatofibrosarcoma protuberans (DFSP) is a rare, low to intermediate grade soft tissue sarcoma originating from the dermal layer of the skin. It is a locally aggressive but rarely metastatic skin tumor, which tends to recur after excision [1]. Although historically it has been attributed as fibroblastic in origin, recent immunohistochemical evidence suggests that it may arise from dendritic cells in the skin. In 1924, Darier and Ferrad first described DFSP as a “progressive and recurring dermatofibroma’’ underscoring its predilection for local recurrence. Despite sharing some histologic features with fibrohistiocytic tumors, DFSP grows in an aggressive, locally infiltrative manner. Despite reports from all body areas, it is most common on the trunk, followed by the extremities, and rarely occurs on the head and neck [2]. While DFSP represents less than 0.1% of all malignant neoplasms, it is the most frequent skin sarcoma (1% of all soft tissue sarcomas). On the head and neck, it represents 1% of all malignant tumors, and 7% of sarcomas [3, 4]. This article describes a case of dermatofibrosarcoma of the scalp in a young female patient. The difficulties in managing this condition in a resource limited setting are highlighted.

Case Report

A 20-year-old female was referred to dermatological Department of the Hassan II university Hospital in Fes, with a massive tumor of his scalp, extending down his front. She had a 10 year history of a large gradually swelling of the frontal region of her scalp. The swelling was non-tender, firm, non transilluminant and non pulsatile. Interrogation of the patient and examination of the records revealed that she had undergone surgery 2 times during the past 10 years for recurrent scalp tumor. Local surgical excision was used in her first operation. Recurrence was detected after 7 years of operation coinciding with her first pregnancy. Incomplete Re-excision was applied in her second operation. Three years after, during the second pregnancy, she developed progressively this giant tumor.

Examination of the patient revealed a scalp tumor 15 cm X 14 cm X 9 cm in dimensions (Figure 1). The tumour was tethered to the overlying skin. Its surface was ulcerative, nodular and firm. The tumor extended from his front down (Figure 1). Systemic examination was unremarkable. No lymph node in the neck, occipital region, or axilla palpable. Her routine laboratory tests were normal. Skull X-ray did not reveal any bony involvement. CT scan was performed. Soft tissue mass in fronto-biparietal region was detected in CT scan without bone involvement or intracranial extensions (Figure 2).

×

Figure1:

Close

Figure 1. A large, non-tender, firm, nodular ‘turban’ tumor with focal ulceration was present in this20 year-old patient.

×

Figure2:

Close

Figure. 2. The prominant soft tissue mass without bone involvement or intracranial extension is noted in this CT scan.

On histological examination, the tumor was located in the dermis with involvement of the hypodermis. The epidermis overlying the tumor was regular and surmounted by orthokeratosis. The tumor was highly cellular consisting of spindle-shaped cells arranged in the characteristic storiform pattern of growth resembling a “straw mat”. Eosinophilic cytoplasm, nuclei few atypical with regular contours, fine chromatin and few mitotic figures were noted. Tumor stroma was inflammatory. Pleomorphism, giant cells and foamy or hemosiderin-laden cells were absent. Skin adnexal structures such as hair follicles, sweat and sebaceous glands were seen entrapped within the tumor (Figures 3 a,b). Immunohistochemical staining showed positivity of CD34 and negativity of S-100 protein (Figure. 4 a,b).

×

Figure3:

Close

Figure 3. a: The typical storiform proliferation of spindle-shaped cells without mitoses is noted in this dermatofibrosarcoma-protuberans. (Hematoxylin and eosin, x40). b: The base of the tumor demonstrates infiltration of the hypodermis.(Hematoxylin and eosin, x100)

×

Figure4:

Close

Figure 4. a: Immunohistochemistry demonstrated positive staining (CD34, 40); b : The spindle-shaped in filtrating cells in the hypodermis demonstrate similar staining (CD34, x100).

Total excision of the tumor with margins of 3 to 5 cm was impossible in places, particularly with forehead extension, nearly orbits. After a multidisciplinary discussion the decision to give the patient chemotherapy treatment by IMATINIB for reduction of the tumor mass was taken. After 9 months of treatment the results were encouraging with a significant reduction of the tumor mass (Figure 5, 6). Surgical resection is then provided after the end of 12 months of treatment with IMATINIB.

×

Figure5:

Close

Figure 5. Three months of treatment with IMATINIB the tumor demonstrates a considerable reduction in size.

×

Figure6:

Close

Figure 6. Nine months of treatment with IMATINIB demonstrated continuing shrinkage of the tumor to the point where surgical excision with 3 – 5 cm margins was practical.

Discussion

Epidemiology

The estimated incidence of DFSP is 4.5 cases per million persons per year in the United States, nearly three in France, and four in Sweden [5]. There are no published incidence reports in Morocco or Africa. DFSP affects either sex but occurs slightly more often in men, with a male-to female ratio of 3:2 [6, 7]. There is some suggestion, however, that women may be at increased risk of the development of DFSP-FS [8]. The incidence among African- Americans compared with Caucasians is almost double (6.5 vs. 3.9 per million) [9]. Although it appears predominantly in adults (30–50 years), it has also been reported in children [6, 8, 10-12]. No evidence of hereditary or familial predisposition exists. The five-year relative survival rates for all reported population-based studies can reach up to 100% [5].

The tumour has marked predilection for the trunk, although, no anatomical region is spared except for hands [13]. Head and neck regions are rarely involved. Burkhardt [14] reported six cases involving the scalp out of 56 cases of dermatofibrosarcoma protuberance. Tamoney [15] in review of cases of dermatofibrosarcoma, found head and neck involvement is 40 out of 261 cases. Mbonde [16] however, reported higher incidence of the tumour in head and neck region and lower limbs, implicating trauma as the probable cause.

Clinical Presentation

Dermatofibrosarcoma protuberans usually presents as an asymptomatic plaque or nodule, purple or pink, with a history of slow but persistent growth [17]. It may start as a small asymptomatic papule, which is likely ignored, and then gradually enlarges into a lumpy nodule or it may evolve into an atrophic and/or sclerotic plaque [18]. Over time, it develops into an ulcerative protuberant tumor. Commonly, DFSP develops superficially and is mobile upon palpation, as it is initially adhered to the overlying skin but not with its underlying tissues. Infiltration of adipose tissue as well as fixation to deeper structures such as fascia and muscle may present in the latter stage of the tumor. Scalp fixation caused by periosteal attachment may occur in early stages due to the thickness of skin and soft tissue in this area. Telangiectasias may be apparent on the surface or at the periphery. Delay in diagnosis and clinical misdiagnosis of the initial lesion is not uncommon and may be due to absence of symptoms or confusion with other benign dermal fibrohistocytic lesions. Pain and tenderness are rare. In addition, cachexia, which usually characterizes advanced malignancies, is also uncommon. Immunosuppression may promote tumor proliferation, as in our case the pregnancy was a risk factor for recurrence. The differential diagnosis in the initial stages should include lipomas, epidermal cysts, keloid, dermatofibroma, and nodular fasciitis. In late stages, when it becomes protuberant, it should be differentiated from pyogenic granuloma, Kaposi sarcoma, and other soft tissue sarcomas [5].

Histopathological Features

Dermatofibrosarcoma protuberans is a slow-growing tumor. It typically arises in the dermis. Although DFSP arises in the dermis, lesions may abut the epidermis, rendering the epidermis attenuated or ulcerated. These tumors infiltrate the dermis and subcutaneous tissue, and some may involve skeletal muscles. Histologically, the tumor is highly cellular and composed of monomorphic, fusiform cells with elongated nuclei showing little or no pleomorphism or hyperchromasia. The cells have little cytoplasm, which usually appears amphophilic to eosinophilic. They are arranged in irregular interwoven fascicles forming a storiform pattern. Mitotic activity is moderate, rarely exceeding five mitoses per 10 high-powered fields.

Lack of multinucleated giant cells and presence of entrapped isolated fat cells are other diagnostic features. Uncommon variants of DFSP include myxoid DFSP, in which myxoid features predominate, and Bednar tumor, which is a pigmented DFSP characterized by the presence of melanin-containing dendritic cells dispersed throughout the tumor [19, 20].

Immunohistochemical staining demonstrates strong positivity for CD34 (sensitivity 84–100%) and negativity for S-100 protein. The diagnosis is easily confirmed by demonstrating strong immunoreactivity for CD34. Areas of fibrosarcomatous change (DFSP-FS), however, are characterized by a herringbone growth pattern, rather than the typical storiform pattern, and possess foci of increased cellularity, cell size, and mitotic activity [15]. Myxoid change also appears to be more prominent in tumors with fibrosarcomatous areas [20]. Immunohistochemically, fibrosarcomatous areas show markedly diminished or absent CD34 immunoreactivity [16].

Staging

Currently, there is no universally accepted staging for DFSP. However, the American Musculoskeletal Tumor Society Staging system is widely used. This takes into account tumor grade and compartmentalization: Stage IA tumors are low-grade intracompartmental (without extension beyond the subcutaneous compartment) lesions that can be managed adequately solely with wide excision; Stage IB tumors are again low-grade lesions that exhibit extracompartmental extension, which involves underlying fascia, muscle, or bone erosion [21]. Meanwhile, Ugurel proposed a staging system according to German Guidelines for DFSP. In this system, stage I represents the primary tumor stage; Stage II describes a DFSP with regional lymph node metastases; and stage III characterizes distance metastases.

Treatment and Prognosis

The treatment for DFSP is wide local excision with histologically negative margins [12, 18, 23]. There is a high local recurrence rate after inadequate excision, and several published series have stressed the importance of wide excision, defined as ≥ 3 cm of clinically uninvolved skin down to and including the fascia. But Arnaud et al [24] noted that it is important to excise a tumour with 5 cm margin during the initial procedure to improve treatment results of DFSP. More recently, Mohs micrographic surgery is being advocated as the treatment of choice, [10] with relatively little chance of recurrence compared to wide local excision. Mohs micrographic surgery allows precise histological mapping of all margins, both deep and lateral. This technique requires continuing sequential horizontal sectioning during resection and immediate frozen microscopic examination, until a free margin is obtained. Owing to the large size of this tumor, the structures involved, and cosmetic considerations in this case, a margin of resection would be 2 to 3 cm. As primary closure is not always feasible, reconstructive surgery using a local skin flap, skin grafting, mesh, or myocutaneous flap may be required.

Although DFSP is non-sensitive to chemotherapy, Ng et al [25] reported a case of pediatric DFSP with chemosensitivity. The patient was given a treatment trial with weekly vinblastine and oral methotrexate. A good partial response was achieved after six weeks, and complete remission had been achieved at the fivemonth follow-up [25]. Interestingly, Rutkowski et al. have reported response of up to 50% using IMANITIB. In our case, the prior imatinib therapy has given good results with considerable reduction in tumor mass that can facilitate the surgical treatment of the tumor.

Radiotherapy is a treatment option for unresectable lesions or in case of margin involvement but has limited value as primary therapy of patients who can be cured by surgery [26]. Although adjuvant radiation seems to provide a benefit for some of the treated patients, the present data remain highly inconclusive regarding the true effectiveness of adjuvant radiation in preventing recurrence and metastasis of DFSP-FS [27].

Local recurrence is most commonly a factor of the margin of resection and tumor subtype [5, 10, 12, 17, 23, 26]. There have been reports of recurrence with tumor margins <2.5 cm for DFSP on the head and neck [5]. There are reports of metastatic disease to the bones, lungs, and even pancreas [5, 12]. These metastases, although rare, are more common with DFSP-FS [23].

The management of a scalp DFSP without local invasion is still controversial. Interestingly, all reports which presented scalp DFSP as a case report were residual tumours after incomplete treatment. Since there is no standard for pre or post-operative adjuvant therapy, incomplete treatment can only be explained with incomplete resection of the tumour in spite of tumor free margins. Diameters of the safety margins were discussed in the literature by the different authors but there is no data related to the depth of resection. Excision of the periosteum of the cranium with shaving of the outer layer should be the first treatment. Reconstruction of the defect could be done with skin grafting for detection of the recurrence in the early period. Patients should be followed for a long time for recurrence and metastasis. After appropriate time, scalp reconstruction can be done for cosmetic reasons with tissue expanders.

DFSP is a rare skin malignancy. This entity is more likely to recur when there is a small margin of excision and head disease. Wide local excision is the gold standard of primary treatment while Imatinib is recommended for the reduction of the tumor mass for large tumors particularly in specific locations such as the scalp and face.