Microvascular and microangiopathic antiphospholipid-associated syndromes ("MAPS"): semantic or antisemantic?

Area of Science:

• Vascular Medicine
• Immunology
• Hematology

Background:

• Antiphospholipid Syndrome (APS) is characterized by recurrent thrombotic events.
• Small vessel occlusions are a known manifestation, affecting organs like kidneys, skin, and eyes.
• Some small vessel occlusions in APS, such as osteonecrosis and hearing loss, remain unproven clinically.

Purpose of the Study:

• To categorize and define the spectrum of microvascular manifestations associated with Antiphospholipid Syndrome.
• To propose a unifying term for thrombotic microangiopathic antiphospholipid-associated syndromes and related conditions.
• To differentiate between proven and unproven small vessel occlusions in APS.

Main Methods:

• Review of clinical presentations and diagnostic criteria for APS-related vascular events.
• Analysis of pathological findings in proven thrombotic lesions.
• Categorization of conditions based on affected vessels and clinical evidence.

Main Results:

• Small vessel occlusions in APS affect glomerular, skin, retinal, bowel, hepatic, or pulmonary vessels, often confirmed by biopsy.
• Unproven manifestations include osteonecrosis, hearing loss, and brain syndromes.
• Thrombotic microangiopathic syndromes (TTP, HELLP) with hemolytic anemia and schistocytes are also linked to APS, with potential for pathogenic antiphospholipid antibodies.

Conclusions:

• The term "MAPS" (Microangiopathic Antiphospholipid-Associated Syndromes) is proposed to encompass both proven and unproven small vessel occlusions and thrombotic microangiopathies in APS.
• This classification aims to improve understanding and diagnosis of APS-related microvascular complications.
• Further research is needed to elucidate the mechanisms by which non-pathogenic antiphospholipid antibodies may become pathogenic, leading to severe events like catastrophic APS.