[11] Catastrophic Antiphospholipid Syndrome (CAPS) Presenting in a Young Child with Trisomy 21

AA Gru, FV White, LP Dehner. Washington University in Saint Louis, Saint Louis, MO

Background: Antiphopholipid syndrome (APS) is an acquired thrombophilic disorder involving autoantibodies against phospholipids (PL) and PL-binding proteins. APS is usually associated with autoimmune disorders, and its frequency is increased in patients with trisomy 21. Catastrophic APS (CAPS) is a rare accelerated form of APS that leads to acute multi-system organ failure, with extensive microscopic thrombosis in multiple organs. First described in 1992, CAPS represents less than 1% of APS cases, but has a mortality rate of 50%. The mean age at presentation is 37 years, with the youngest reported case occurring in a 7 year old child.
Design: We report the autopsy findings of a unique case of CAPS in a 2 year old child with trisomy 21, presenting after an insidious onset of rash. The case met all major criteria for CAPS including: involvement of 3 or more organs systems, manifestations occurring within a week, positive serology for anti-PL antibodies, and microscopic evidence of thrombosis in at least 1 organ.
Results: A two year old girl with trisomy 21 and a past medical history including surgically treated congenital heart disease presented with a skin rash that was initially thought to be a drug hypersensitivity reaction, but with subsequent rapid development of abdominal distention and livedo reticularis. A skin biopsy revealed an ischemic epidermis, with dermal hemorrhage and microthrombi. Pneumatosis intestinalis and frank air within the portal vein accompanied the bowel distention and two subsequent intestinal resections revealed fulminant ischemic enterocolitis with micothrombi in mesenteric vessels. An extensive rheumatologic work-up revealed lupus anticoagulant, anticardiolipin antibodies, and hypocomplementemia. Despite aggressive therapy, the patient expired and an autopsy was permitted. Grossly, there were extensive areas of skin breakdown simulating Steven-Johnson's reaction. The remaining intestines and spleen had multiple infarcts without grossly evident thrombi. Microscopically, several organs including intestines, skin, heart, and spleen, had marked congestion and microthrombi. Immunohistochemistry for C4d revealed extensive complement deposition within the blood vessels.
Conclusions: CAPS is a rare entity with only a few published cases. The pathogenesis is thought to involve massive activation of complement, as demonstrated in this case. This is the first reported case of CAPS occurring in a young child and associated with trisomy 21. The relationship between them still remains to be established.
Category: Autopsy

Wednesday, March 11, 2009 1:00 PM

Poster Session VI # 13, Wednesday Afternoon