Dermatofibrosarcoma Protuberans of Face: A Rare Entity and Review of Literature

Abstract

Dermatofibrosarcoma protuberans is a very rare tumour that accounts for less than 0.1% of all malignant neoplasms. It is a locally aggressive tumour with high recurrence rate. Head and neck involvement is very uncommon and hence diverse treatment protocols have been recommended for its management in the currently available literature. We present a case of dermatofibrosarcoma protuberans over the lower part of right cheek in a middle aged male, which was successfully treated with wide local excision and reconstruction along with post-op radiotherapy. The patient was followed-up for 18 months with no recurrence. Prompt and accurate diagnosis along with multidisciplinary treatment is crucial for optimal management of this rare tumor. The optimal treatment option is surgical resection with wide margins along with adjuvant radiotherapy, which leads to better outcomes even in patients with positive surgical margins. Larger clinical trials with Imatinib will firmly establish its chemotherapeutic role in its management. Lifelong regular follow-up is essential for early detection of tumor.

Introduction

Dermatofibrosarcoma protuberans (DFSP) of the head and neck is a rare cutaneous low grade sarcoma characterized by high chance of local recurrence and low metastatic potential. It accounts for less than 0.1% of all malignant neoplasms and approximately 1% of all soft tissue sarcomas. This condition was first described by Darier in 1924. It commonly involves the trunk (42–72%), extremities (16–30%) and rarely involves the head and neck (10–16%) [1].

Case Report

A 40 year old male presented to Head and Neck Oncology services at our institute with complaints of a painless swelling over the right lower part of cheek since past three months. The lesion was insidious in onset and gradually progressing in size with no history of trauma. On examination, a single non-tender 6 × 5 cm brownish-red plaque with irregular surface and margins with subcutaneous induration was present at the right angle of mandible (Fig. 1). The biopsy revealed dermatofibrosarcoma protuberans. CT scan showed ill-defined minimally enhancing soft tissue density mass lesion around the right angle of mandible with ill-defined fat plane between the lesion and the underlying masseter muscle with no underlying bony erosion. The patient under underwent wide excision of lesion with 4–5 cm margin under general anaesthesia. Due to patient’s financial constraints, the surgical defect was reconstructed with a 12 × 10 cm pectoralis major myocutaneous flap instead of a microvascular free-flap (Fig. 2). Histopathology revealed spindle shaped cells arranged in storiform or cartwheel pattern extending just beneath the skin into the subcutaneous tissue, suggestive of DFSP (Fig. 3a). On immunohistochemistry, the tumour cells were positive for CD34 and vimentin and negative for CD31, SMA and S100 which helped to confirm the diagnosis and establish that the excised margins were tumour—free (Fig. 3b). The patient subsequently received 60 cGy of radiation. The patient’s recovery period was uneventful and 18 months after treatment, he was symptom-free with no signs of recurrence (Fig. 4).

Fig. 1.

A brownish-red plaque with irregular surface and margins seen at the right angle of mandible

Fig. 2.

Wide local excision with reconstruction with pectoralis major myocutaneous (PMMC) flap

Fig. 3.

a DFSP is characterised by spindle shaped cells arranged in storiform or cartwheel pattern extending just beneath the skin (H & E stain, 10×). b DFSP showing positivity for CD34 on immunohistochemistry

Fig. 4.

6 months post-operative photograph showing completely healed head & neck region

Discussion

The exact cause of DFSP is unknown, but in 10–20% of cases a history of trauma can be elicited. It may also arise from surgical scars, old burn scars and sites of immunizations [2]. The median age for patients with DFSP is 39–45 years and it is more common in men. The surface of the lesion usually presents as irregular protuberant swelling or as a hard indurated plaque usually involving the trunk, proximal extremities and rarely the head and neck region. It is slow-growing lesion and may appear violaceous, blue-red or brown. It is a locally aggressive tumour which rarely metastasis to lung, bone, and lymph nodes [2]. The differential diagnosis of this lesion includes keloid, hypertrophic scar, morphea, cutaneous melanoma, dermatofibroma or basal cell carcinoma [3]. Hence an early biopsy will help to identify the tumor accurately and prevent misdiagnosis.

DFSP arises from chromosomal translocation t(17, 22) (q22, q13). Its histopathology shows a distinct “cartwheel” or “storiform” arrangement of uniform appearing fibroblasts with CD34 + on immunohistochemistry that helps to differentiate them from fibrosarcomas and malignant fibrous histiocytomas [4]. Only 5% are considered to be high-grade “fibrosarcomatous DFSP” or DFSP-FS which is often associated with significant risk of both local recurrence and distant metastasis [5]. The predictors of poor clinical outcome include age greater than 50 years, high mitotic index, increased cellularity, DFSP-FS variant and positive surgical margins.

The American Musculoskeletal Tumor Society (MSTS) staging system for DFSP takes into account tumour grade and compartmentalization [6]. Stage IA tumours are low-grade, intra-compartmental lesions while Stage IB tumours are low-grade lesions that exhibit extra-compartmental extension with involvement of underlying fascia or muscle. German Guidelines for DFSP has also been used for its staging [7].

Previously, conservative surgical resection (< 3 cm) along with classic histologic vertical processing lead to unacceptably high recurrence rates varying from 26 to 60% [8]. But with adoption of wide local excision (3–5 cm margin), the local recurrence rates has dropped to around 20% [9]. Nearly 50% of DFSP recurrences after surgery have been observed within 1 year and 80% within the first 3 years [9]. The high recurrence rates have been attributed to various factors that include failure to excise clinically inapparent projections of the tumour and inability of vertical histologic processing of tissues to pick up asymmetric outcroppings. The tumour’s benign nature can be misleading to both patient and surgeon alike.

Mohs micrographic procedure enables microscope-assisted complete removal of tumour and is highly effective in managing smaller DFSP lesions (< 3 cm) [10]. This procedure has several disadvantages as it may require multiple sittings (mean 2.4, range 1–5) to achieve complete tumour removal and cannot be used for large tumours and DFSP-FS variant. Besides it requires a highly trained surgeon.

Radiotherapy serves as an adjuvant in the management of DFSP in addition to wide local excision, especially if surgical margins are positive. Conservative resection is possible with the use of post-operative radiotherapy, especially where preservation of cosmetic and functional outcome is of prime importance. The number of patients in various studies undergoing post-operative radiotherapy is very small to draw strong conclusions.

The recent understanding in the role of PDGF B – PDGF R signalling pathway in the pathogenesis of DFSP has lead to targeted inhibition of PDGFRs with Imatinib [11]. This is particularly useful in the treatment of patients with locally advanced lesions and metastatic disease that cannot achieve complete surgical resection [11].

Patients with tumour recurrence are usually dealt by salvage wide local excision followed by adjuvant radiotherapy (dose 40–60 Gy). If the tumour is inoperable, it is downsized with either pre-operative radiotherapy or Imatinib and then surgical excision is planned.

Since DFSP has high metastatic potential, lifelong follow-up has been recommended. The workup for recurrent DFSP should include cross-sectional imaging (CT scan or MRI scan) of tumour, CT scan of chest, PET scan and tissue biopsy to confirm diagnosis prior to initiation of therapy.

Conclusion

The optimal treatment option for patients with DFSP is surgical resection with wide margins. The use of adjuvant radiotherapy in patients with positive surgical margins and recurrences improves the likelihood of cure. Horizontal histologic processing along with use of immunohistochemistry would facilitate better tumor detection at the periphery. Larger clinical trials with Imatinib will firmly establish its chemotherapeutic role in the management of DFSP. Lifelong regular follow-up is essential for early detection of tumor.

Funding

None.

Declarations

Conflict of Interest

The authors declare that they have no conflict of interest.

Informed Consent

Informed consent has been obtained from the patient for this publication.