Hemicraniectomy as a surgical treatment for intracranial pressure following large ischemic lesions is widely practiced in selected patients. The antiphospholipid antibody syndrome (APS), a disorder characterized by recurrent arterial and venous thrombosis, is a very rare cause of space occupying ischemic lesions. We present a case of a 35 year old female diagnosed with APS who initially presented with small ischemic lesions and within days developed a massive near-total infarction of the right hemisphere. Because of central nervous system, skin and systemic manifestations Sneddon's syndrome and catastrophic antiphospholipid antibody syndrome (CAPS) remained a possible diagnoses. Sneddon's syndrome is a non-inflammatory occlusive arteriopathy of small and medium size arteries predominantly of the skin and brain, whereas the catastrophic antiphospholipid antibody syndrome is characterized by acute multi-organ system thrombosis of small and large vessels. In addition to the diagnostic criteria for APS a heterozygous factor V Leiden mutation was found in this patient, which may be a contributing risk factor for cerebral ischemia. When considering invasive decompressive procedures the neurosurgeon has to be aware of the poor prognosis of some forms of APS with systemic manifestations.