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| Fig. 38.3 Systemic amyloidosis. Extensive purpura in a patient with diffuse, cutaneous systemic amyloidosis. A skin biopsy demonstrated amyloid deposited in the dermis and subcutaneous tissue. (Courtesy of the Fitzsimons Army Medical Center teaching files.) |
In primary systemic amyloidosis, immunoglobulin light-chain proteins and serum amyloid P (SAP) are deposited in skin, tongue, heart, spleen, joints, peripheral nerves, and carpal ligaments due to an underlying plasma cell dyscrasia or multiple myeloma. Cutaneous changes may be present, including purpura of the upper trunk, face, and neck and eyelid purpura, which is very characteristic of primary systemic amyloidosis (Fig. 38-3). Waxy papules, particularly on the palms and fingertips, have also been reported. Secondary systemic amyloidosis is due to chronic inflammatory diseases such as tuberculosis and other infections, connective tissue diseases, hidradenitis suppurativa, and familial periodic fever syndromes, and is due to deposition of a distinctive nonimmunoglobulin protein designated AA (amyloid A protein), of which the precursor is an acute-phase reactant produced by the liver. Cutaneous lesions due to amyloid deposits are rarely seen in this type of amyloidosis. Even when there are no cutaneous changes present, skin biopsy may help make a diagnosis of primary or secondary systemic amyloidosis. Clinically, normal skin, abdominal fat, tongue, rectal, and minor salivary gland biopsies have been used to confirm the diagnosis, thus avoiding the need for more invasive biopsies of internal organs.
Wong CK, Wang WJ: Systemic amyloidosis. A report of 19 cases,
Dermatology 189:47–51, 1994.
