The genetics of pyoderma gangrenosum and implications for treatment: a systematic review

Are neutrophilic dermatoses autoinflammatory disorders?

Neutrophils constitute essential players in inflammatory responses and are the first line of defence against harmful stimuli. However, dysregulation of neutrophil homeostasis can result in excessive inflammation and subsequent tissue damage. Neutrophilic dermatoses are a spectrum of inflammatory disorders characterized by skin lesions resulting from a neutrophil-rich inflammatory infiltrate in the absence of infection. The exact molecular pathophysiology of neutrophilic dermatoses has long been poorly understood. Interestingly, neutrophil-rich cutaneous inflammation is also a cardinal feature of several autoinflammatory diseases with skin involvement, the latter being caused by aberrant innate immune responses. Overactivation of the innate immune system leading to increased production of interleukin-1 family members and 'sterile' neutrophil-rich cutaneous inflammation are features of both inherited autoinflammatory syndromes with skin involvement and an increasing number of neutrophilic dermatoses. Therefore, we propose that autoinflammation may be a cause of neutrophilic dermatoses.

Ocular pyoderma gangrenosum: A systematic review

BACKGROUND

Pyoderma gangrenosum (PG) is a rare, ulcerative cutaneous disorder. Ophthalmic involvement in PG is atypical, but can have devastating consequences.

OBJECTIVE

We sought to characterize ocular PG to allow for earlier diagnosis and therapy. To our knowledge, this is the first systematic review summarizing this clinical variant.

METHODS

A systematic review was conducted using PubMed and Web of Science. Data were extracted and studies were qualitatively assessed and analyzed.

RESULTS

We identified all 34 cases of PG involving the eye and periorbital area, and categorized them into 4 different subtypes. Common presenting signs include ulceration, peripheral ulcerative keratitis, and decreased visual acuity. Although it is often difficult to biopsy ocular PG, histologic features are nonspecific. Combined therapy using corticosteroids and further surgical reconstruction as needed is the mainstay of treatment. Cases of the eye/orbit in particular should be treated aggressively, as these are more likely to relapse compared with cases of the periorbital area.

LIMITATIONS

Use of case reports, paucity of ocular PG cases, and heterogeneity of studies are limitations.

CONCLUSION

PG should be considered in the differential diagnosis of ulceration of ocular/periocular tissues. An aggressive, early, multimodal treatment strategy should be used to prevent relapse, especially in cases of the eye/orbit.

Pyoderma gangrenosum and its syndromic forms: evidence for a link with autoinflammation

Pyoderma gangrenosum is a rare inflammatory neutrophilic dermatosis manifesting as painful ulcers with violaceous, undermined borders on the lower extremities. It may occur in the context of classic syndromes like PAPA (pyogenic arthritis, pyoderma gangrenosum and acne) and SAPHO (synovitis, acne, pustulosis, hyperostosis, osteitis), as well as in a recently described entity named PASH (pyoderma gangrenosum, acne and suppurative hidradenitis). Pyoderma gangrenosum has recently been included within the spectrum of autoinflammatory diseases, which are characterized by recurrent episodes of sterile inflammation, without circulating autoantibodies and autoreactive T cells. In PAPA syndrome, different mutations involving the PSTPIP1 gene, via an increased binding affinity to pyrin, induce the assembly of inflammasomes. These are molecular platforms involved in the activation of caspase 1, a protease that cleaves inactive prointerleukin (pro-IL)-1β to its active isoform IL-1β. The overproduction of IL-1β triggers the release of a number of proinflammatory cytokines and chemokines, which are responsible for the recruitment and activation of neutrophils, leading to neutrophil-mediated inflammation. In SAPHO syndrome, the activation of the PSTPIP2 inflammasome has been suggested to play a role in inducing the dysfunction of the innate immune system. Patients with PASH have recently been reported to present alterations of genes involved in well-known autoinflammatory diseases, such as PSTPIP1, MEFV, NOD2 and NLRP3. Pyoderma gangrenosum and its syndromic forms can be regarded as a single clinicopathological spectrum in the context of autoinflammation.

Intravenous Immunoglobulins: Mode of Action and Indications in Autoimmune and Inflammatory Dermatoses

Intravenous immunoglobulins (IVIGs), a mixture of variable amounts of proteins (albumin, IgG, IgM, IgA, and IgE antibodies), as well as salt, sugar, solvents, and detergents, are successfully used to treat a variety of dermatological disorders. For decades, IVIGs have been administered for treatment of infectious diseases and immune deficiencies, since they contain natural antibodies that represent a first-line defense against pathogens. Today their indication has expanded, including the off-label therapy for a variety of autoimmune and inflammatory diseases. In dermatology, IVIGs are administered for treatment of different disorders at different therapeutic regimens, mostly with higher doses then those administered for treatment of infectious diseases. The aim of this prospective review is to highlight the indications, effectiveness, side effects, and perspectives of the systemic treatment with IVIGs for patients with severe, life-threatening, and resistant to conventional therapies autoimmune or inflammatory dermatoses.

Pathophysiology of pyoderma gangrenosum (PG): an updated review

Pyoderma gangrenosum is a challenging skin condition to identify and treat because of its multifactorial pathogenesis. It is a rare cutaneous manifestation diagnosed clinically by exclusion of infection, neoplasia, thrombophilia, and other inflammatory conditions. Pathogenetic and treatment studies are scarce. Abnormalities in the function of inflammatory cytokines, the immune system, and neutrophils combined with specific genetic mutations predispose patients to develop this complex disease process. Early recognition of patients at risk for pyoderma gangrenosum, the necessity to improve its early diagnosis, and the future outlook of targeted and personalized therapies relies on the improved comprehension of the complex pathogenesis of pyoderma gangrenosum.

Pyoderma gangrenosum and Sweet syndrome: the prototypic neutrophilic dermatoses

Pyoderma gangrenosum, a dramatic ulcerative skin disease, and Sweet syndrome, a papular dermatosis, were described independently. It was subsequently shown that they share many characteristics, including clinical overlap and the frequent association with multisystemic disorders. The group of the neutrophilic dermatoses encompasses these two dermatoses, as well as other conditions having in common an aseptic neutrophilic infiltrate predominating in the epidermis and/or the dermis and/or the subcutis. Some patients also experience neutrophilic infiltrates in other organs, defining the neutrophilic disease. Recent research suggests that the neutrophilic dermatoses could be considered as the cutaneous expression of the autoinflammation, an aberrant hyperproduction of interleukin-1. Autoinflammation is responsible for monogenic diseases, and is also involved in the mechanism of many polygenic conditions, including the neutrophilic dermatoses.

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.