Leg ulceration is a rare skin finding in patients with SLE, and usually occurs in patients with APS and/or leucocytoclastic vasculitis. It reported in adult studies of cases of SLE that it had noted leg ulcers in 5-8 % of them [4, 6]. In a study in Turkey, although mucocutaneous lesions were 97,8 % in children with SLE, the skin ulcers were not reported [1]. PG is associated with a systemic disease, most commonly infammatory bowel disease, arthritis, and hematologic malignancy, in at least half of the cases [7] . PG may precede, coexist, or follow the different systemic diseases. The association of PG with SLE, however, is rarely encountered. In most of these reports, PG had developed years after the diagnosis of SLE[8]. PG had developed two years after the diagnosis of SLE in our patient. Most of the SLE patients associated with PG had antiphospholipid antibody positivity as in our patient (9). Though in some reports, ulcers observed in antiphospholipid antibody positive SLE patients are designated as PG like ulcers, it is not clear yet whether this discrimination is appropriate or not, as they show only minor diferences in comparison to the real PG lesions [10, 11]. Diagnosis of PG is based mainly on the morphology of the lesions, clinical course, exclusion of other conditions, and response to certain medication including steroids and calcineurin inhibitor. Therefore, we initially administered steroid and tacrolimus to our patient. However, there was no response to these treatments. There are no specific immunohistopathologic findings and pathognomonic laboratory tests for PG. Histopathological examination of the ulcer may help to differentiate PG from some of its mimickers [12]. When her skin biopsy findings is reassessed in keeping with the anticardiolipin antibody results, it was noticed by pathologist that her biopsy findings were suggestive a small vessel vasculopathy rather than vasculitis. The exact pathomechanisms of the association of between SLE and PG are not thoroughly explained. However, the presence of antiphospholipid antibody suggests that mechanisms predisposition to vascular thromboses or infammation may also have contributed [13].
The therapeutic strategy in the general context of neutrophilic dermatosis as PG consists in modulating activation, maturation or migration of neutrophils (with colchicine, corticosteroids and immunosuppressive). Interestingly, drugs able to modulate connective tissue diseases activity like SLE (such as hydroxychloroquine, methotrexate, mycophenolate mofetil) were reported effective on neutrophilic skin lesions in the literatüre [14, 15]. However, the need for anticoagulation therapy and unresponsiveness to immunosuppressive only therapy confirmed also the diagnosis of SLE secondary development APS in our patient.
APS is an autoimmune disorder characterized by recurrent venous thrombosis or arterial occlusive events associated with elevated levels of antiphospholipid antibodies. APS may occur in association with SLE in childhood as well as in adults [16]. The prevalence of antiphospholipid antibodies found to be higher in healthy children (5–20%) [17]. However, it is difficult to predict the actual prevalence of APS in the pediatric population due to the absence of validated criteria for its diagnosis or classification. The cutaneous manifestations of APS vary from livedo reticularis to cutaneous necrosis. Ulcers resembling PG have been described seldom in APS and may cause confusion in diagnosis [18, 19]. In addition, less than one third of patients with APS show histologic evidence of coagulopathy [20]. However, it can be said that APS is a highly problematic simulator of PG because of the low specificity of histologic findings in patients with APS and its frequent response to anticoagulation therapy. It is important to have these informations about APS to prevent misdiagnosis and delayed diagnosis.
SLE and APS are systemic autoimmune conditions which can present with a wide range of clinical manifestations related both to disease itself and to comorbidities. Based in clinical, pathological and response to proposed treatment, we can state that leg ulcers in patients with APS could be considered as a secondary form of PG. we recommend that testing for antiphospholipid antibodies should be performed in the initial evaluation of patients with SLE, and should be re-evaluated if new risk factors for thromboembolic events emerge.