Amyloid purpura

Amyloid purpura
Purpura
Specialty	Dermatology

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.

Presentation

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

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]

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. 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.
2. Gamba G, Montani N, Anesi E, et al. (March 2000). "Clotting alterations in primary systemic amyloidosis" (PDF). Haematologica. 85 (3): 289–92. PMID   10702818.
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.