Accelerated healing of pyoderma gangrenosum treated with bioengineered skin and concomitant immunosuppression

Surgical Treatment of Pyoderma Gangrenosum with Negative Pressure Wound Therapy and Skin Grafting, Including Xenografts: Personal Experience and Comprehensive Review on 161 Cases

Significance: Pyoderma gangrenosum (PG) is a rare debilitating autoinflammatory ulcerative skin disease. No gold standard has been established for the treatment of PG. The role of surgical interventions and negative pressure wound therapy (NPWT) was discussed controversially until recently as these procedures might pose a trigger to further aggravate the condition. Recent Advances: Recent advances confirm the paradigm change that a surgical approach of PG with split thickness skin grafting (STSG) secured by NPWT is a safe and valuable treatment if performed under adequate immunosuppression. We elaborate this on the hand of a broad literature search retrieving 101 relevant articles describing 138 patients complemented with our personal experience on 23 patients, including 2 patients treated with a porcine xenodressing. Critical Issues: A wide range of surgical approaches have been reported, including xenografts. Treatment was finally successful in 86%, including the xenotransplant cases. Ten percent improved and failures were mainly reported without immunosuppression. Despite halting the inflammatory process, NPWT alone, without skin grafting, does not much accelerate healing time. The best surgical approach appears to be STSG fixed with NPWT as this leads to higher skin graft take. There remains the problem of the chronic nature of PG and the recurrence after tapering of immunosuppression or trauma; therefore, a sustained immunosuppressive treatment is suggested. Future Directions: While surgical treatment is supported by the published data, the exact immunosuppression is still evolving. Due to deeper insights into pathogenesis and growing clinical reports, a broader utilization of biologic treatments and a shift from tumor necrosis factor (TNF)-alpha to interleukin (IL)-12/23 or IL-23 antibodies alone are predictable, as IL-12/23 antibodies show good clinical responses with fewer side effects. The positive results with porcine xenodressings might be due to immunological effects of the xenomaterial; they appear promising, but are preliminary and should be confirmed in a larger patient collective.

Cadaveric Skin Grafts May Greatly Increase the Healing Rate of Recalcitrant Ulcers When Used Both Alone and in Combination With Split-Thickness Skin Grafts

BACKGROUND

Leg ulcers that do not heal despite appropriate treatment are defined as recalcitrant ulcers. Large surface area, depth, and long duration represent some of most important factors impeding ulcer healing. After sharp debridement, dermal substitutes including skin from cadaver donors may increase the healing rate of recalcitrant ulcers reducing the risk of scar formation and recurrence.

OBJECTIVE

Assessing if, after sharp debridement, dermal substitutes including skin from cadaver donors may increase the healing rate of recalcitrant ulcers reducing the risk of scar formation and recurrence.

PATIENTS AND METHODS

Among patients admitted to our hospital for all types of chronic leg ulcers, we retrospectively reviewed the records of patients affected by recalcitrant ulcers (surface greater than 100 cm, tissue loss involving epidermis, dermis, and subcutaneous tissue, duration longer than 1 year, and showing no healing tendency). After sharp debridement, the ulcers were covered by allografts with strict follow-up after discharge. Multiple allografts were performed when necessary, and a final autograft was applied in case of incomplete healing.

RESULTS

The records of 414 patients were analyzed. Forty-three patients were lost at follow-up, and the remaining 371 healed after 765 grafting procedures. In 163 patients, the ulcers healed by means of a final autograft. In all the remaining cases, allograft led to ulcer healing.

CONCLUSION

Allografts represent an effective treatment option in case of recalcitrant, large, deep and long-lasting leg ulcers.

When is Recalcitrant Pyoderma Gangrenosum Truly Recalcitrant?

Background:

The literature supports many different therapies used in recalcitrant pyoderma gangrenosum, which suggests that the pathophysiology is not yet understood. Our hypothesis is that certain patient demographic factors, including age or size of ulcer at presentation, may predict a poor clinical outcome.

Objective:

The goal of our study was to stimulate an analysis of pyoderma gangrenosum treatment failures to identify predisposing conditions that would increase the likelihood of failure.

Conclusion:

Patients older than 50 years of age or with an ulcer greater than 25 cm in diameter may have a poor outcome, but a systematic review of pyoderma gangrenosum treatment failures should be undertaken to support this hypothesis.

Cutaneous Tissue Engineering and Lower Extremity Wounds (Part 2)

In a previous article, this group described the principles involved in the development of bioengineered skin equivalents that held out much promise. This article has examined some of the uses of such products in treating venous ulcers, diabetic foot ulcers, and skin diseases leaving skin wounds. Data encouraging the use of such products in certain indications are available. The costs of using such products are also appreciated.

Pyoderma Gangrenosum

Pyoderma Gangrenosum is cutaneous manifestation of a systemic problem that should be systematically diagnosed and managed with care. When such lesions appear on legs, it is important to study and treat the systematic problem.

Pyoderma gangrenosum: challenges and solutions

Pyoderma gangrenosum (PG) is a rare disease, but commonly related to important morbidity. PG was first assumed to be infectious, but is now considered an inflammatory neutrophilic disease, often associated with autoimmunity, and with chronic inflammatory and neoplastic diseases. Currently, many aspects of the underlying pathophysiology are not well understood, and etiology still remains unknown. PG presents as painful, single or multiple lesions, with several clinical variants, in different locations, with a non specific histology, which makes the diagnosis challenging and often delayed. In the classic ulcerative variant, characterized by ulcers with inflammatory undermined borders, a broad differential diagnosis of malignancy, infection, and vasculitis needs to be considered, making PG a diagnosis of exclusion. Moreover, there are no definitively accepted diagnostic criteria. Treatment is also challenging since, due to its rarity, clinical trials are difficult to perform, and consequently, there is no “gold standard” therapy. Patients frequently require aggressive immunosuppression, often in multidrug regimens that are not standardized. We reviewed the clinical challenges of PG in order to find helpful clues to improve diagnostic accuracy and the treatment options, namely topical care, systemic drugs, and the new emerging therapies that may reduce morbidity.

Safety and Efficacy of a Bilayered Skin Construct in Full-Thickness Surgical Wounds

This was a prospective, randomized, controlled clinical trial assessing the safety and efficacy of a living bilayered skin construct (BSC; Organogenesis, Canton, MA) in treating full-thickness surgical excision wounds. We enrolled 31 patients needing excision of a non-melanoma skin cancer. The patients consisted of 18 females and 13 males, with an average age of 67 years (range: 44 to 84 years). Patients were randomized to either receive a single application of BSC or to heal by secondary intention. Endpoints to assess efficacy included time to complete wound closure, intensity and duration of post-operative pain, cosmetic appearance, patient satisfaction, and quality of the healed wound. Endpoints to assess safety included infection at the wound site and rejection of the BSC. Findings indicate that BSC is safe in the post-operative treatment of acute surgical wounds for removal of non-melanoma skin cancer. The data also suggest that BSC may facilitate management by decreasing post-operative pain. It is unclear whether or not BSC decreases healing time of acute wounds or results in a better cosmetic outcome.

A case of pyoderma gangrenosum with ulcerative colitis treated with combined approach: infliximab and surgery

Pyoderma gangrenosum (PG) is an ulcerating noninfectious disease of the skin seen in 1-2% of patients with inflammatory bowel disease (IBD). The pathogenesis of PG has yet to be determined, but may be related to abnormal T cell responses and the production of TNF-α, a pathway also involved in IBD pathogenesis. Infliximab, a chimeric monoclonal antibody to TNF-α, is used to treat moderate to severe IBD and several case reports and studies suggest the efficacy of infliximab in the treatment of PG. The surgical approach to PG is reserved to a few selected cases. We report here the case of a patient with ulcerative colitis (UC) and PG localized on the left breast, treated with a simultaneous combined medical and surgical approach.

Management of neutrophilic dermatoses

Neutrophilic dermatoses, including Sweet's syndrome, pyoderma gangrenosum, and rheumatoid neutrophilic dermatitis, are inflammatory conditions of the skin often associated with underlying systemic disease. These are characterized by the accumulation of neutrophils in the skin. The associated conditions, potential for systemic neutrophilic infiltration, and therapeutic management of these disorders can be similar. Sweet's syndrome can often be effectively treated with a brief course of systemic corticosteroids. Pyoderma gangrenosum, however, can be recurrent, and early initiation of a steroid-sparing agent is prudent. Second-line treatment for both of these conditions includes medications affecting neutrophil function, in addition to immunosuppressant medications.

Bioengineered skin constructs and their use in wound healing

BACKGROUND

Over the past two decades, the field of wound healing and tissue repair has witnessed tremendous advances resulting from the biological sciences, biomedical and tissue engineering, and greater clinical understanding of wounds and their pathophysiology. In large part because of these advances, clinicians are now able to offer and deliver more sophisticated and effective treatments to patients with acute wounds, chronic wounds, burns, and other types of injuries.

METHODS

This report relies on published information focused on bioengineered skin and the authors' perspectives on the application of this technology in wound healing. In some cases, off-label applications of certain bioengineered skin constructs have been used to illustrate the spectrum of usefulness of these constructs.

RESULTS

Bioengineered skin (including acellular and cellular products; living and nonliving constructs; and epidermal, dermal, and bilayered therapeutic adjuncts) has resulted in very substantial and demonstrable improvements in wound care. Some of the constructs are U.S. Food and Drug Administration approved for treatment of burns and for impaired healing situations, including venous and diabetic foot ulcers.

CONCLUSIONS

The advances that have occurred in testing and proving the efficacy of bioengineered skin hold great promise for further improvements in the way this technology is used in the surgical field and in wound care. Advances in therapeutic agents have also led to greater understanding of pathophysiology. Thus, wound bed preparation as a concept and as an approach is in fact the result of the need to maximize the benefits of advanced therapies.

Unusual causes of cutaneous ulceration

Skin ulceration is a major source of morbidity and is often difficult to manage. Ulcers caused by an inflammatory cause or microvascular occlusion are particularly challenging in terms of diagnosis and treatment. The management of such ulcers requires careful assessment of associated systemic conditions and a thorough analysis of the ulcer's clinical and histologic findings. In this article, the authors discuss several examples of inflammatory ulcers and the approach to the diagnosis and treatment of these ulcers.

Medical and surgical management of paraneoplastic pyoderma gangrenosum--a case report and review of the literature

We present a case of a 44-year-old male with pyoderma gangrenosum (PG) presenting simultaneously with diagnosis of acute leukemia. His skin disease was stabilized with corticosteroids and most lesions cleared after chemotherapy-induced remission of the malignancy, but the largest lesion remained necrotic. Surgical treatment of the large necrotic ulcer included debridement followed by split-thickness skin graft while maintaining corticoid therapy. Unfortunately, relapse of the pyoderma gangrenosum with bullous lesions heralded relapse of the ultimately fatal malignancy. This case illustrates: (1) PG presenting simultaneously with a haematologic malignancy (2) Relapse with atypical bullous lesions with return of the malignancy and (3) The use of surgical modalities in managing patients with PG, a disease notorious for surgical complications.

Pyoderma gangrenosum: an update

Pyoderma gangrenosum (PG) can be differentiated into classic and atypical forms. The classic form is characterized by ulcers and the atypical form by deep erosions with bullous blue-gray margins. Pathergy, the development of cutaneous lesions at sites of trauma, is a common feature of both forms of PG. Approximately 50% of patients who have PG have underlying systemic diseases, most commonly inflammatory bowel disease, myeloproliferative disorders, and various forms of inflammatory arthritis. The diagnosis of PG is one of exclusion. The management of this disorder begins with treatment of any underlying disease and local or systemic glucocorticoids or immunomodulating therapies.

The role of fibroblasts in tissue engineering and regeneration

Fibroblasts are mesenchymal cells that can be readily cultured in the laboratory and play a significant role in epithelial-mesenchymal interactions, secreting various growth factors and cytokines that have a direct effect on epidermal proliferation, differentiation and formation of extracellular matrix. They have been incorporated into various tissue-engineered products such as Dermagraft (Advanced BioHealing, La Jolla, CA, U.S.A.) and Apligraf (Novartis, Basel, Switzerland) and used for a variety of clinical applications, including the treatment of burns, chronic venous ulcers and several other clinical applications in dermatology and plastic surgery. In this article we review the cell biology of dermal fibroblasts and discuss past and current experience of the clinical use of cultured fibroblasts.

Pyoderma gangrenosum--a review

Pyoderma gangrenosum (PG) is a rare noninfectious neutrophilic dermatosis. Clinically it starts with sterile pustules that rapidly progress and turn into painful ulcers of variable depth and size with undermined violaceous borders. The legs are most commonly affected but other parts of the skin and mucous membranes may also be involved. Course can be mild or malignant, chronic or relapsing with remarkable morbidity. In many cases PG is associated with an underlying disease, most commonly inflammatory bowel disease, rheumatic or haematological disease and malignancy. Diagnosis of PG is based on history of an underlying disease, typical clinical presentation, histopathology, and exclusion of other diseases that would lead to a similar appearance. The peak of incidence occurs between the ages of 20 to 50 years with women being more often affected than men. Aetiology has not been clearly determined yet.

The treatment of PG is a challenge. Randomized, double-blinded prospective multicenter trials for PG are not available. The best documented treatments are systemic corticosteroids and ciclosporin A. Combinations of steroids with cytotoxic drugs are used in resistant cases. The combination of steroids with sulfa drugs or immunosuppressants has been used as steroid-sparing modalities. Anti-tumor necrosis alpha therapy in Crohn's disease showed a rapid response of PG. Skin transplants and the application of bioengineered skin is useful in selected cases as a complement to the immunosuppressive treatment. Topical therapy with modern wound dressings is useful to minimize pain and the risk of secondary infections. Despite recent advances in therapy, the prognosis of PG remains unpredictable.

Basic approach to inflammatory ulcers

Cutaneous ulcers are a difficult problem. A multidisciplinary approach is often adapted in caring for patients with nonhealing wounds. Internists, surgeons, dermatologists, and nurses must work together to provide a patient with the most comprehensive care possible. Dermatologists are consulted for a number of reasons, particularly if the ulcers are secondary to an inflammatory process. In this discussion, we describe a basic and useful approach to the diagnosis and management of inflammatory ulcers. The spectrum of these conditions is wide, ranging from vasculitis, to pyoderma gangrenosum, to ulcers resulting from the antiphospholipid syndrome and cryoprecipitates. The present authors will emphasize that the approach needs to be all-encompassing, and not focused on the ulceration alone. Certain clues are critical to diagnosis. The management, whereas often difficult, can be very rewarding.

Update on tissue-engineered biological dressings

Tissue-engineered biological dressings offer promise in the treatment of burns, chronic ulcers, donor site and other surgical wounds, and a variety of blistering and desquamating dermatologic conditions. For example, the prevalence of diabetic foot ulcers ranges from 4.4% to 10.5% of diabetics, resulting in 82,000 lower extremity amputations annually; venous leg ulcers affect 0.18% to 1.35% of the population; and pressure ulcers are found in 5.0% to 8.8% of institutionalized patients and 14.8% of patients in acute care facilities. Despite the large number of potential beneficiaries, cellular tissue-engineered products have suffered setbacks in recent years and have garnered considerably lower market share than commercial promoters anticipated. The mechanism of action of these products is not universally agreed upon, but delivery of growth factors and extracellular matrix components to the wound is thought to be important; graft "take" is not usually considered to occur. These "engineered" products do not specifically match a treatment modality to an underlying pathology. Clinical effect is often modest, and sometimes not justi- fiable from a cost-benefit perspective. Nevertheless, clinical reports in the literature of uses of tissueengineered biological dressings continue to mount, indicating that these products are finding niche applications where clinical utility is high and the cost can be defended. Despite commercial setbacks, the first-approved products, Dermagraft, Apligraf, and Cultured Epidermal Autograft (Epicel) are still being marketed, and new ones, such as OrCel, continue to be developed. The major indications for these products are summarized and a brief review of the available clinical literature is offered.

Evaluation of ApligrafR persistence and basement membrane restoration in donor site wounds: a pilot study

Apligraf is a bilayered tissue-engineered product consisting of a bovine collagen matrix with neonatal fibroblasts, overlaid by a stratified epithelium containing living keratinocytes. The United States Food and Drug Administration has approved its use for venous leg ulcers and neuropathic diabetic foot ulcers. Apligraf provides a dermal matrix and produces cytokines similar to the human skin. However, its mechanism of action and ultimate fate in host wounds are unclear. The aim of this study was to evaluate the persistence of Apligraf fibroblasts and keratinocytes in human acute partial-thickness wounds (split-thickness donor sites) treated with Apligraf. In an open-label, within-patient, three-centered, controlled pilot study, 10 patients were treated with Apligraf, Apligraf dermis only (without epidermis), and a polyurethane film for donor site wounds of the same size, depth, and anatomical location. Apligraf DNA persistence was the primary outcome measure. Basement membrane components, cosmetic outcome, time to wound healing, and safety parameters were secondary outcome measures. One week after the initial treatment, reverse transcription polymerase chain reaction analysis found that two Apligraf and two Apligraf dermis-only-treated sites had Apligraf DNA present. Four weeks posttreatment, only one Apligraf and one Apligraf dermis-only sites showed the presence of Apligraf DNA. There was no difference between the three treatment modalities in establishing basement membrane in donor site wounds. No differences in other secondary outcomes were found. Apligraf DNA persisted in a minority of patients at 4 weeks in acute partial-thickness wounds. Apligraf's success in speeding healing of acute wounds appears to be related to factors other than the persistence of donor DNA or effect on basement membrane restoration.

Treatment recommendations for pyoderma gangrenosum: an evidence-based review of the literature based on more than 350 patients

Because the incidence of pyoderma gangrenosum (PG) is low, no prospective randomized controlled trials and only a few studies with case numbers of more than 15 patients have been published. To date no guidelines for treatment of PG have been established far. The aim of the study was to provide an evidence-based review of the literature and an evaluation of recommendations for PG treatment. We performed an electronic search using the PubMed database and the term "pyoderma-gangrenosum." Literature published in the English language during the past two decades was reviewed. All relevant studies that could be obtained regardless of the study design were evaluated for grades of recommendation and levels of evidence. Data on patient characteristics including severity of the disease, localization of lesions, associated diseases, and treatment procedures were abstracted and evaluated for therapeutic outcome. We conclude that therapeutic efficacy of systemic treatment with corticosteroids and cyclosporine is best documented in the literature for disseminated as well as for localized disease and should be considered first-line therapy. In cases that do not respond to this treatment, we recommend alternative therapeutic procedures (eg, systemic treatment with corticosteroids and mycophenolate mofetil; mycophenolate mofetil and cyclosporine; tacrolimus; infliximab; or plasmapheresis), considering additional factors including associated diseases.

Other uses of homologous skin grafts and skin bank bioproducts

The main use of homologous skin grafts or grafts of related bioproducts is in the treatment of severe burns. However, various new clinical and experimental sectors, in which this type of skin substitute can be useful, have recently emerged. The main new clinical indications for skin allografts include: skin loss, surgical wounds and bullous diseases. In these fields donor skin can be used for different purposes: as a physiological biological dressing to control pain and protect deep structures such as tendons, bones, cartilage and nerves, and to promote reepithelization with a significant reduction in healing time, and as skin substitute with dermal tissue to guide repair and make it as physiological as possible. In particular, skin bank bioproducts are currently used in the treatment of several conditions such venous and arterial leg ulcers, pressure ulcers, diabetic foot ulcers, pyoderma gangrenosum, post traumatic lesions, Mohs surgery, reconstructive surgery, wound cover in critical areas, aesthetic surgery, congenital epidermolysis bullosa and Lyell's syndrome. Skin bank bioproducts have also been used for experimental indications, to study in vitro toxicology and in vitro skin biology. Recently the demonstration that de-epidermized dermis (DED) has all the characteristics of an excellent dermal substitute into which various types of cells can be introduced and made to develop, opens exciting new possibilities of research in the field of wound healing and tissue engineering. Our preliminary observations seems to indicate that CD 34+ stem cells from umbilical cord blood can survive in DED and in a few weeks populate collagen bundles. The observation of tubular structures without lumina close to collagen bundles as well as clusters of epithelioid or fibroblast-shaped cells may represent aspects of differentiation of CD 34+ stem cells. More detailed and sophisticated studies are clearly needed to answer all the questions that these initial observations pose. Anyway the 3-dimensional model proposed seems to be suitable for the study of the behaviour of peripheral CD 34+ and perhaps also other types of stem cells in 3-dimensional dermal matrix.

Clinical classification of bioengineered skin use and its correlation with healing of diabetic and venous ulcers

BACKGROUND

Chronic wounds are being treated with bioengineering skin constructs. Yet, there is no standard way of assessing these wounds. We developed a classification system to evaluate wounds after construct application. The classification system evaluates the early clinical effect of bioengineered skin and early construct appearance giving a total score named the skin substitute score.

OBJECTIVE

Apply classification system to both venous and diabetic foot ulcers and determine whether classification system has validity and predictability for healing.

METHODS

Evaluated serial photographs in 83 and 78 patients with diabetic foot ulcers and in 84 and 83 patients with venous ulcer on Days 7 and 14, respectively, treated with a bilayered bioengineered skin construct. Applied the classification system and determined the percentages of healed patients.

RESULTS

There was a significant correlation between better skin substitute score and complete wound closure for both venous ulcers p=0.002 on Day 7 and p=0.01 on Day 14) and diabetic foot ulcers p=0.0005 on Day 7 and p<0.0001 on Day 14).

CONCLUSION

Optimal clinical effect was associated with complete wound closure. As the clinical effect becomes less than optimal continued clinical persistence of the construct becomes important. This classification system seems to have validity in predicting complete wound closure in wounds treated with a bilayered bioengineered skin construct.

Optimal treatment of pyoderma gangrenosum

The optimal treatment of pyoderma gangrenosum includes a combination of local wound care and systemic medications. Oral and pulse intravenous corticosteroids have traditionally been the most commonly recommended first-line systemic therapies. Cyclosporine, with or without corticosteroids, has more recently emerged as a first-line systemic treatment. A multitude of immunosuppressive and immune-modulating medications, as well as antimicrobial agents with anti-inflammatory properties have also been widely prescribed. Often, it is difficult to achieve control of aggressive cases of pyoderma gangrenosum, necessitating administration of a combination of systemic therapies. Furthermore, patients recalcitrant to one or many medications are frequently reported. Concomitant disease, intolerance to a class of medications, and the patient's response to prior therapies can help guide a practitioner in choosing the optimal treatment of pyoderma gangrenosum.

Giant right plantar keloid treated with excision and tissue-engineered allograft

Plantar keloids are a management problem as a result of the pain and mechanic restriction with ambulation. We present the treatment of a patient with a particularly large plantar keloid that was refractory to multiple excisions, adjunctive intralesional steroids, and radiation therapy, who was successfully treated with excision, intralesional steroids, and tissue-engineered allograft placement.

Evaluation of tissue-engineered skin (human skin substitute) and secondary intention healing in the treatment of full thickness wounds after Mohs micrographic or excisional surgery

BACKGROUND

Human Skin Substitute (Apligraf, Organogenesis, Inc., Canton, MA) is a bi-layered tissue-engineered living biological dressing developed from neonatal foreskin. It consists of a bovine collagen matrix containing human fibroblasts with an overlying sheet of stratified human epithelium containing living human keratinocytes. Human Skin Substitute (HSS) appears to be immunologically inert, and has shown usefulness in the treatment of chronic and acute wounds.

OBJECTIVE

Primary objectives were to evaluate the safety and efficacy of HSS in the treatment of full-thickness wounds in a prospective case series. Secondary objectives were to determine the rate of complete wound reepithelialization, incidence of complete wound healing, pain at wound site, overall cosmetic outcome, and patient satisfaction.

METHODS

Fourteen patients were enrolled in the study, of which 12 were evaluable. HSS was applied in a blinded fashion to 6 of the patients immediately following Mohs or excisional surgery for skin cancer. The remaining 6 patients were allowed to heal by secondary intention. Both groups were evaluated at weekly appointments until complete reepithelialization occurred. During each evaluation, wound quality was assessed through the Vancouver Burn Scar Assessment Scale by the investigator and an independent blinded dermatologist. The investigator, blinded observer, and patient further evaluated the cosmetic outcome of the wound through the use of a Visual Analog Scale over a 6-month period.

RESULTS

HSS patients and secondary intention patients were equivalent in comorbid factors such as pain, erythema, edema, exudate, infection, or hematoma between the groups. The incidence of complete wound healing at 6 months was 100% for both groups. Both groups also appeared to heal at similar rates, as defined by the complete reepithelialization of the wound. HSS patients ultimately resulted in more pliable and less vascular wounds as defined by the Vancouver Burn Scar Assessment Scale. Patient satisfaction with cosmetic outcome in both groups was positive at 6 months.

CONCLUSIONS

HSS appears to be a safe, well-tolerated biological dressing with equivalent comorbid factors to secondary intention healing. HSS, however, seems to produce a more pliable and less vascular scar than those developed through healing by secondary intention. HSS also appears to produce more satisfactory cosmetic results when compared to secondary intention healing.

Neutrophilic dermatoses

The neutrophilic dermatoses are a group of related cutaneous disorders that frequently have systemic manifestations or associations. While there are distinct clinical differences in the classical lesions of these disorders, there are many patients who have overlapping features. In addition, the associated systemic manifestations or associated diseases are often similar among these disorders. Finally, the management of these disorders with the frequent use of corticosteroids and nonsteroidal immunosuppressive or immunomodulatory agents is common.

Clinical management of pyoderma gangrenosum

Pyoderma gangrenosum is a noninfectious neutrophilic dermatosis that usually starts with sterile pustules which rapidly progress to painful ulcers of variable depth and size with undermined violaceous borders. In 17 to 74% of cases, pyoderma gangrenosum is associated with an underlying disease, most commonly inflammatory bowel disease, rheumatological or hematological disease or malignancy. Diagnosis of pyoderma gangrenosum is based on a history of an underlying disease, typical clinical presentation and histopathology, and exclusion of other diseases that would lead to a similar appearance. Randomized, double-blinded prospective multicenter trials investigating the treatment of pyoderma gangrenosum are not available. The treatments with the best clinical evidence are systemic corticosteroids (in the initial phase usually 100 to 200 mg/day) and cyclosporine (mainly as a maintenance treatment). Combinations of corticosteroids with cytotoxic drugs such as azathioprine, cyclophosphamide or chlorambucil are used in patients with disease that is resistant to corticosteroids. The combination of corticosteroids with sulfa drugs, such as dapsone, or clofazimine, minocycline and thalidomide, has been used as a corticosteroid-sparing alternative. Limited experience has been documented with methotrexate, colchicine, nicotine, and mycophenolate mofetil, among other drugs. Alternative treatments include local application of granulocyte-macrophage colony-stimulating factor, intravenous immunoglobulins and plasmapheresis. Skin transplants (split-skin grafts or autologous keratinocyte grafts) and the application of bioengineered skin is useful in selected cases in conjunction with immunosuppression. Topical therapy with modern wound dressings is useful to minimize pain and the high risk of secondary infection. The application of topical antibacterials cannot be recommended because of their potential to sensitize and their questionable efficacy, but systemic antibacterial therapy is mandatory when infection is present. Despite recent advances in therapy, the prognosis of pyoderma gangrenosum remains unpredictable.

Pyoderma gangrenosum: a report of 21 cases

BACKGROUND

Pyoderma gangrenosum (PG) is an uncommon, destructive, cutaneous ulceration, belonging to the neutrophilic disease spectrum. It is associated with systemic disease in 50% of cases.

METHODS

We report a retrospective study of 21 cases of PG. All cases studied fulfilled the following criteria: (i) clinical features of PG; (ii) histopathology consistent with a diagnosis of PG, and excluding other specific dermatoses.

RESULTS

The average age of our patients was 41.8 years. The male to female ratio was 1.1. The typical ulcerative variant was found in 17 patients, bullous PG in two patients, and the granulomatous variant in two patients. Sixty-two per cent of our patients had lesions on their lower legs. Two patients had neutrophilic pulmonary involvement concurrent with the ulcers. An association with other internal diseases was noted in 12 patients. Histopathologic study showed vasculitis in 13 patients. Of these, 11 were leukocytoclastic and the others predominantly lymphocytic.

CONCLUSIONS

PG is a rare disease, with the ulcerative variant being most frequent. The lower legs are the most commonly affected sites. The recurrence rate in our study was about 46% regardless of the treatment prescribed. Pulmonary involvement was fatal in two patients.

Tissue-engineered skin substitutes

The last two years have seen new tissue-engineered skin substitutes come onto the market and begin to resolve the various roles to which each is best suited. It is becoming evident that some of the very expensive cell-based products have cost-benefit advantage despite their high price and are valuable within the restricted applications for which they are intended. The use of skin substitutes for testing purposes has extended from epidermal keratinocytes to other integumentary epithelia and into preparations containing multiple cell types in which reactions resulting from paracrine interactions can be examined. Challenges remain in the application of gene therapy techniques to skin substitutes, both the control of transgene expression and in the selection of suitable genes to transfect. A coming challenge is the production of tissue-engineered products without the use of animal products other than human cells. A challenge that may be diminishing is the importance of acute rejection of allogeneic tissue-engineered skin substitutes.