Infectious etiologies of acrocyanosis and digital limb ischemia were ruled out by appropriate studies. Our patient had a history of recent dental work prior to symptom onset, which prompted evaluation for infective endocarditis with echocardiography and blood cultures. He had thrush, raising concern for candidemia, but again, blood cultures were negative. Hepatitis C-associated cryoglobulinemia was ruled out with hepatitis ABS and cryoglobulin levels.
Other less likely etiologies to be considered include chikungunya, psittacosis and mononucleosis, Coxiella burnetiid and Bartonella, but he had no travel history and did not have birds, dogs or cats at home.
Dermatologic Manifestations
Livedo reticularis, cutaneous ulceration and necrosis, digital gangrene and subungual splinter hemorrhages are among the cutaneous manifestations of APS seen by Cervaro et al. Livedo reticularis was the third most common presenting sign of APS and was prevalent at disease onset (40.4%). Only behind deep vein thrombosis (31.7%) and thrombocytopenia (21.9%), it is also present in 70% of patients with concomitant SLE and APS. The mottling of the skin seen in nonphysiologic livedo reticularis is likely due to dysfunction of blood flow resulting in the collection of deoxygenated blood between arterioles supplying adjacent (i.e.,1 to 4 cm) zones of the skin, likely from aPL autoantibodies directed at phospholipid protein complexes bound to endothelial cells within the vessels resulting in procoagulant release and thrombosis. Livedo reticularis is more commonly a physiologic response to cold exposure or hypotension; thus, on its own, it is a non-specific finding. There is no proven treatment for livedo reticularis, with low-dose aspirin often prescribed without proven efficacy.
Much less common are the manifestations of APS present in our patient, a constellation of microvascular thrombotic events that can include ulceration, necrosis and digital gangrene of the skin. Cutaneous necrosis (2.1% of patients) can be acute, painful, and widespread. These lesions may develop from peripheral erythema to necrotic bullae. Pathologic examination demonstrates non-vasculitic and non-inflammatory thrombosis of the dermal vasculature. Subungual splinter hemorrhages (0.7% of patients) are frequently associated with acute or previous thrombotic events. Digital gangrene (3.1% of patients) is a significant thrombotic event that can be caused by the blockage of large-, medium- or small-sized vessels in the limbs.
Criteria
Diagnostia criteria for APS were established by Wilson et al. in 1999.1 Since then, the body of literature regarding the disease has grown, leading to a revised consensus classification criteria for APS set forth by Miyakis et al. in 2006, with the major revisions listed in Table 3.2 The classification requires at least one clinical criterion and one laboratory criterion.
