Pyoderma gangrenosum (PG) is an uncommon, noninfective, ulcerating disorder which most commonly affects the skin, and the ulcers are most found on the trunk and lower extremities. Extra-cutaneous manifestations of PG wherein other organs are affected are rare. PG rarely affects the eye, orbit, or adnexa. Ophthalmic involvement in PG is atypical, however it can result in devastating visual consequences.
This rare ulcerating neutrophilic dermatosis affects 3 to 10 patients per million. Reported cases of ophthalmic involvement with PG are a few dozens. Generally, the demographics of patients with ocular PG appear to be slightly different from classic PG. PG most commonly occurs in patients between 20 and 50 years of age, although most patients with ocular PG were older than 60 years. It has a slight predilection for females, and an ethnic/cultural predisposition is not apparent.
Much like classic PG, the most common finding was neutrophil infiltration/acute inflammatory infiltrate. Necrosis, dermal abscesses, and chronic inflammatory infiltrate were also described. Histopathologic findings depend on the site and stage of the biopsy, with early lesions or biopsies from the periphery showing moderate perivascular lymphocytic infiltrate associated with vascular endothelial swelling. More advanced lesions and central areas show abscess formation with ulceration and dense lymphocytic infiltration around (and involving) blood vessels, with thrombosis and extravasation of erythrocytes. In the late stages, the disease is characterized by almost complete replacement of the dermis by a neutrophil-laden inflammatory cell infiltrate, in which only the main cutaneous adnexal structures (such as hair follicles) remain intact. Two thirds of patients with ulcerative PG have associated systemic diseases, particularly arthritis, inflammatory bowel disease, monoclonal gammopathy, or malignancy.
The clinical appearance of neutrophilic dermatoses, of which PG is one type, is largely dependent on which of the cutaneous layers the disease is centered: it presents as a pustular eruption if predominantly epidermal, as papules or plaques if dermal, or as deeply ulcerating nodules if the neutrophil infiltrate is centered in the subdermal tissues.
PG is notoriously difficult to diagnose, primarily because of nonspecific clinical and histopathological features. Ocular PG is no different. The lesions of PG are often purulent in appearance centrally, suggesting infection. Periocular disease appears to present s painful eyelid swelling and nodules that, if unrecognized and untreated, progress to frank full-thickness ulceration of the eyelids. This necrosis appears characteristically to spare the marginal bar of upper lid tarsus (alongside the tarsomarginal artery) and to favor the central one third of the upper lid and lateral two thirds of the lower lid. Intraorbital (postseptal) extension is rare and tends to occur deep to the lateral canthus.
The diagnostic evaluation of a patient in whom PG is suspected must have two main aims—to exclude other causes of ulceration as causative and to determine the presence of a treatable, associated, and systemic disorder. Samples should be taken from any exudate and directly from the affected tissue for microscopy, culture and sensitivity to exclude an infective cause. Although biopsy may lead to extension of the ulcerated area via pathergy it should be strongly considered as it can exclude the presence of infection, a vasculitis or malignancy. Obtaining multidisciplinary advice regarding a patient suspected to have PG early is important. Help can be sought from Dermatology, Infectious Disease and Rheumatology teams
Treatment of ulcerative PG requires analgesia, treatment of local infection at the site of disease and systemic therapy, and both for the pyoderma itself and for any underlying systemic condition. Several treatments have been assayed in patients suffering from ocular PG, including local therapy with external dressings and/or intralesional corticosteroids. Systemic corticosteroids are usually given orally but also as intravenous pulses in certain serious cases. Other reported treatment options include local and systemic immunosuppressors (i.e. cyclosporine A and anti–TNF-α), antibiotics, surgical procedures such as skin graftings, and hyperbaric oxygen therapy. Surgical intervention is generally avoided in PG because of the possibility of a pathergic reaction. However, some have suggested that after stabilization of the disease with immunosuppressants, adjuvant surgery may improve wound healing and reduce morbidity. Removing necrotic tissue in selected cases may help to avoid bacterial infections, for example. Such treatment should be undertaken in conjunction with systemic immunosuppressive therapy during a controlled and quiescent period of any associated systemic disease
Signs of improvement of PG lesions may be seen within days, although studies have reported that complete healing of classic PG lesions may take several months. Eighteen ocular PG cases reported the time from initiation of treatment to resolution of lesions: 2 cases healed in 1 week or less, 7 cases in 1 week to 1 month, 6 in 1 to 6 months, and 3 in 6 months to 1 year. Relapse of PG lesions is exceedingly common, with recurrence rates of typical PG being reported as high as 39% in some studies. As for outcomes in patients with ocular PG, an interesting association was found between location and relapse. Cases involving only the eye/orbit were more prone to relapse in comparison with cases of the periorbital area.
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