DISCUSSION
Pyoderma gangrenosum being a rare disease was first elaborated in 1930 and described as a chronic destructive inflammatory, noninfectious skin disease with recurrence tendency.1,2 PG lesions typically present as painful, erythematous pustules, bullae, or nodules.1,3-6 They may evolve into necrotic plaques with raised edges or into violaceous deep ulcers with undermined bluish borders, healing with atrophic or cribriform scars. Such description matches with what was seen in our case report.1,2,4-8
PG affects mainly adults aged between 20 to 50 years with female predilection. It account for only 4% of cases in children and adolescents with a higher incidence of head and perineal involvement. PG has preponderance of pustular lesions, and a frequent history of trauma.1-3,5,6,8-10 The commonest presentation of PG in children is disseminated ulcerative lesions. 1,6,8
The actual pathogenesis of PG has remained to be idiopathic though it has been postulated to be a neutrophilic disorder characterized by dysregulation of the immune system, such as overexpression of growth factors and interleukins, especially interleukin (IL)-1, (IL)-6 and (IL)-8 and tumor necrosis factor (TNF)-a.10
Though the etiology has been idiopathic in majority of cases, in about fifty-percent of cases, it’s associated with neoplasms and/or systemic inflammatory illnesses, such as Behcet’ disease, ulcerative colitis and Crohn’s disease.4,7 More recently, PG has been associated with novel drug therapies like pegfilgrastim.2
The diagnosis of pediatric PG is often delayed, with an average of 2 months due to its lower prevalence among children and because it can be misdiagnosed with other ulcerative diseases. 1,2,6This correlate with what was seen in this case where the diagnosis was delayed for 6-months.
Though there are no histopathological findings specific to PG, but skin biopsy should be performed to rule out other etiologies.1.3,4,6 In resource limited settings, its diagnosis remains to be clinical.
Once the diagnosis of pediatric PG is confirmed, clinicians are recommended to identify for an underlying etiology as the disease can be the initial presentation of a systemic disorder.1 This was a challenge to our case since the patient was residing at a resource-limited setting.
The head and neck region may be affected by PG, although to date only few cases of ear involvement have been reported.1,6,8This is the first novel case reported in our country involving the external ear.
To date, there is no gold standard treatment or published algorithm for choice of therapy for pediatric PG though treatment should be tailored according to the underlying etiology. It includes systemic steroids, corticosteroid sparing agents such as dapsone and cyclosporine, and TNF-alpha inhibitors such as adalimumab and infliximab. Response to treatment is high with cure rates reaching 90%.6,10
Our patient achieved a rapid response when treated with steroids with no recurrence after 6-months of follow up thus laying emphasis on the role of steroids in PG. Auricular cases previously reported showed good response to the classical therapeutic strategy based on the use of corticosteroids or neutrophil chemotaxis inhibitors and thus use of these drugs as first choice. No cases of auricular PG treated with anti-TNF-biologic agents have been reported from the available literatures. Thus, its value in managing refractory cases of auricular PG is unknown, as already shown in PG of other sites.10 Despite the good response to steroids manifested in auricular PG cases, yet clinicians must expect episodes of flare-up in some patients, as usually observed in most cases of typical pyoderma. No flare has been reported in this case report.