Free flap failure in antiphospholipid syndrome: a microangiopathic mechanism beyond thrombosis

Antiphospholipid syndrome (APS), a multisystem autoimmune disorder characterized by arterial and venous thromboses, poses a significant risk to the success of free flap reconstruction. While the literature documents near-complete failure rates in patients with APS undergoing microsurgical procedures, comprehensive reports of intraflap microvascular complications are scarce. We present two cases of complex scalp reconstruction patients with APS, both exhibiting progressive flap ischemia from the periphery to the center despite preserved arterial and venous Doppler signals. This pattern—marbled or livedo reticularis-like skin changes—suggested a microvascular pathogenesis, consistent with a lesser-known subtype of APS: microangiopathic antiphospholipid syndrome (MAPS). In both cases, immunologic evaluation confirmed the diagnosis of APS, prompting initiation of intravenous immunoglobulin (IVIG) therapy and immunosuppressive agents, which led to flap salvage and eventual wound closure. Our findings advocate for early multidisciplinary collaboration between microsurgeons and immunologists in suspected APS cases. Furthermore, we propose that marbled flap appearance in the context of preserved pedicle signals may be an early clinical sign of MAPS, warranting prompt immunologic intervention to optimize outcomes.