Amyloid purpura

Amyloid purpura is a condition marked by bleeding under the skin (purpura) in some individuals with amyloidosis.^[1] Its cause is unknown, but coagulation defects caused by amyloid are thought to contribute.

Cause

The precise cause of amyloid purpura is unknown, but several mechanisms are thought to contribute.^[2] One may be a decrease in the level of circulating factor X,^[2] a clotting factor necessary for coagulation. The proposed mechanism for this decrease in factor X is that circulating amyloid fibrils bind and inactivate factor X.^[2] Another contributing factor may be enhanced fibrinolysis,^[2] the breakdown of clots. Subendothelial deposits of amyloid may weaken blood vessels and lead to the extravasation of blood.^[2][3] Amyloid deposits in the gastrointestinal tract and liver may also play a role in the development of amyloid purpura.^[2]

Distribution

Amyloid purpura usually occurs above the nipple-line and is found in the webbing of the neck and in the face and eyelids.^[1]

Epidemiology

Amyloid purpura affects a minority of individuals with amyloidosis.^[1] For example, purpura is present early in the disease in approximately 15% of patients with primary systemic amyloidosis.^[4]

References

1. ^ ^{a b c} Eder L, Bitterman H (June 2007). "Image in clinical medicine. Amyloid purpura". N. Engl. J. Med. 356 (23): 2406. doi:10.1056/NEJMicm061510. PMID 17554122. http://content.nejm.org/cgi/pmidlookup?view=short&pmid=17554122. 
2. ^ ^{a b c d e f} Gamba G, Montani N, Anesi E, et al. (March 2000). "Clotting alterations in primary systemic amyloidosis". Haematologica 85 (3): 289–92. PMID 10702818. http://www.haematologica.org/cgi/reprint/85/3/289.pdf. 
3. ^ Amyloidosis, Immunoglobulin-Related at eMedicine
4. ^ Kyle RA, Gertz MA (January 1995). "Primary systemic amyloidosis: clinical and laboratory features in 474 cases". Semin. Hematol. 32 (1): 45–59. PMID 7878478. 

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