Double-layer biodegradable temporising matrix reconstruction for abdominal skin and soft-tissue reconstruction

Background

Dermatofibrosarcoma protuberans (DFSP) is a rare slow growing and locally aggressive sarcoma of dermal origin.1 It accounts for 1% of soft-tissue sarcomas, and has an incidence of around 1–5 cases per million population per year.2 They are most commonly found over the trunk, and can present as skin-coloured, non-tender cutaneous plaques, which over time become nodular, hard and protuberant.3 Although these tumours rarely metastasise, they are highly locally invasive and easily recurring.4 Surgical management with either wide local excision (WLE) with 1–5 cm margins, or Mohs micrographic surgery (MMS), forms the mainstay of treatment.5 Radiotherapy may be offered as adjuvant treatment when resection margins are positive or whenever conservative surgical management is required.6

Partial-thickness abdominal wall defects involve the loss of skin and subcutaneous tissues but retain an adequate musculofascial domain.7 Pedicled or free tissue transfer can provide adequate soft-tissue coverage for large abdominal wall defects; however, the necessity for tumour-free surgical margins precludes its immediate use.7 These would also ideally be tissue expanded ahead of reconstruction, which has oncological considerations if margins are not clear.

While skin grafts are a reasonable reconstructive option, they do not offer the durability or cosmesis of a flap reconstruction. Skin grafts, particularly on the abdominal wall, have a predilection for plaque-like scarring and significant contraction and hypertrophy.8 These are often difficult to manage in the long-term postoperative period, aside from the cosmetic consequences of this in a prominent area of the body.

As an alternative, artificial dermal templates have been utilised to create a suitable wound bed for grafting, with the aim to recreate the inherent thickness and pliability of skin.9 NovoSorb biodegradable temporising matrix (BTM) is a 2 mm thick, synthetic dermal matrix used for complex wound reconstruction. It typically involves a two-stage procedure: implantation of the bilaminar matrix allowing for host integration and creation of neodermis; and subsequent delamination of the superficial membrane and application of split thickness skin graft over the vascularised matrix. BTM has been shown to be a safe and reliable reconstructive option in complex wounds including acute burns, necrotising fasciitis and free flap donor site reconstruction.10

We describe an alternative, aesthetic and low-morbidity technique to reconstructing a large, partial thickness abdominal wall defect following WLE of DFSP, using two layers of a novel synthetic dermal matrix (NovoSorb BTM), to achieve an improved contour in a patient with a step defect of approximately 3 cm. We demonstrate that abdominal wall reconstruction using double-layer BTM can better mimic the thickness and pliability of skin and subcutaneous tissues, and offers improved durability and cosmesis compared with skin grafting or indeed single layer skin substitutes alone, without the significant challenges and risks posed by flap reconstruction. To our knowledge, a double-layer BTM has never been described for abdominal wall reconstruction.

Case presentation

A young woman in her early 20s, with no significant medical history, was referred to our outpatient clinic with a large, firm mass over the right flank. The patient reported that the mass had grown considerably in the preceding 2 months and become tender and firm. On examination, there was a 5×6 cm firm, tender lesion over the right anterolateral abdomen, underlying a congenital naevus. There was no palpable cervical, axillary or inguinal lymphadenopathy.

Investigations

The patient underwent an ultrasound scan demonstrating a 4×4×3 cm well defined, mixed solid cystic mass located in the subcutaneous tissues. Non-contrast MRI of the abdomen was subsequently performed, showing a 4.8×3.8×4.8 cm soft-tissue lesion with peripheral enhancement in the right anterolateral abdominal wall, abutting and distorting the underlying musculature with no frank infiltration. An ultrasound-guided core biopsy was performed, and histological analysis confirmed DFSP with high-grade features. There was no evidence of metastasis on CT chest, abdomen and pelvis.

Treatment

After discussion at the regional sarcoma multidisciplinary team meeting, the patient underwent a WLE of the tumour with 3 cm peripheral margins. The tumour was excised en bloc down to muscle, resulting in a large 10×14 cm subfascial defect. After careful haemostasis and saline irrigation, a 2 mm layer of BTM was cut to shape and applied to the defect. The BTM was secured using simple interrupted 4–0 prolene sutures with careful quilting and dressed with foam and Hypafix (BSN Medical, Hamburg, Germany). The patient was discharged the same day. Histopathological examination of the specimen demonstrated a well differentiated, 6×8 cm dermatofibrosarcoma with clear peripheral and deep margins. There were no plans for postoperative radiotherapy.

The patient returned to our dressing clinic on a weekly basis for dressing changes. At 2 weeks, the BTM had completely adhered to the wound and demonstrated signs of integration (see figure 1). By 6 weeks, the BTM was salmon pink in colour, with capillary refill demonstrable through the seal, suggesting that the wound bed was ready for grafting. A second layer of BTM was planned to be applied to improve the significant contour deformity of the tumour bed. As a day-case procedure under local anaesthesia, the BTM was delaminated, the surface refreshed by dermabrasion and a second layer of BTM applied to the wound and secured using 5–0 prolene simple interrupted sutures (see figure 2).

After complete integration by 7 weeks, the patient underwent application of split thickness skin graft to the wound, under a general anaesthetic as a day-case procedure (see figure 3). The graft was harvested from the right thigh, inset using 4–0 vicryl rapide (Ethicon) and skin glue, and dressed with Jelonet, gauze and Hypafix.

Outcome and follow-up

At 14 days postoperatively, the skin graft had fully taken, and donor site healed (see figure 4). By 14 weeks, the scar had started to mature with no obvious contour defect or contracture, and no evidence of local and regional tumour recurrence (see figure 5). Overall, the contour was improved compared with grafting alone or single layer ADM, and the skin pliability was notably good.