Chapter 054. Skin Manifestations of Internal Disease (Part 20)

Pink Lesions The cutaneous lesions associated with primary systemic amyloidosis are often pink in color and translucent. Common locations are the face, especially the periorbital and perioral regions, and flexural areas. On biopsy, homogeneous deposits of amyloid are seen in the dermis and in the walls of blood vessels; the latter lead to an increase in vessel wall fragility. As a result, petechiae and purpura develop in clinically normal skin as well as in lesional skin following minor trauma, hence the term pinch purpura. Amyloid deposits are also seen in the striated muscle of the tongue and result in...
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Chapter 054. Skin Manifestations of Internal Disease (Part 20) Chapter 054. Skin Manifestations of Internal Disease (Part 20) Pink Lesions The cutaneous lesions associated with primary systemic amyloidosis areoften pink in color and translucent. Common locations are the face, especially theperiorbital and perioral regions, and flexural areas. On biopsy, homogeneousdeposits of amyloid are seen in the dermis and in the walls of blood vessels; thelatter lead to an increase in vessel wall fragility. As a result, petechiae and purpuradevelop in clinically normal skin as well as in lesional skin following minortrauma, hence the term pinch purpura. Amyloid deposits are also seen in thestriated muscle of the tongue and result in macroglossia. Even though specific mucocutaneous lesions are rarely seen in secondaryamyloidosis and are present in only ~30% of the patients with primaryamyloidosis, a rapid diagnosis of systemic amyloidosis can be made by anexamination of abdominal subcutaneous fat. By special staining, deposits are seenaround blood vessels or individual fat cells in 40–50% of patients. There are alsothree forms of amyloidosis that are limited to the skin and that should not beconstrued as cutaneous lesions of systemic amyloidosis. They are macularamyloidosis (upper back), lichenoid amyloidosis (usually lower extremities), andnodular amyloidosis. In macular and lichenoid amyloidosis, the deposits arecomposed of altered epidermal keratin. Recently, macular and lichenoidamyloidosis have been associated with MEN syndrome, type 2a. Patients with multicentric reticulohistiocytosis also have pink-coloredpapules and nodules on the face and mucous membranes as well as on the extensorsurface of the hands and forearms. They have a polyarthritis that can mimicrheumatoid arthritis clinically. On histologic examination, the papules havecharacteristic giant cells that are not seen in biopsies of rheumatoid nodules. Pinkto skin-colored papules that are firm, 2–5 mm in diameter, and often in a lineararrangement are seen in patients with papular mucinosis. This disease is alsoreferred to as generalizedlichen myxedematosus or scleromyxedema. The lattername comes from the brawny induration of the face and extremities that mayaccompany the papular eruption. Biopsy specimens of the papules show localizedmucin deposition, and serum protein electrophoresis and/or immunofixationelectrophoresis demonstrates a monoclonal spike of IgG, usually with a λ lightchain. Yellow Lesions Several systemic disorders are characterized by yellow-colored cutaneouspapules or plaques—hyperlipidemia (xanthomas), gout (tophi), diabetes(necrobiosis lipoidica), pseudoxanthoma elasticum, and Torre syndrome(sebaceous tumors). Eruptive xanthomas are the most common form of xanthomasand are associated with hypertriglyceridemia (types I, III, IV, and V). Crops ofyellow papules with erythematous halos occur primarily on the extensor surfacesof the extremities and the buttocks, and they spontaneously involute with a fall inserum triglycerides. Increased β-lipoproteins (primarily types II and III) result inone or more of the following types of xanthoma: xanthelasma, tendon xanthomas,and plane xanthomas. Xanthelasma are found on the eyelids, whereas tendonxanthomas are frequently associated with the Achilles and extensor finger tendons;plane xanthomas are flat and favor the palmar creases, face, upper trunk, andscars. Tuberous xanthomas are frequently associated with hypertriglyceridemia,but they are also seen in patients with hypercholesterolemia (type II) and are foundmost frequently over the large joints or hand. Biopsy specimens of xanthomasshow collections of lipid-containing macrophages (foam cells). Patients with several disorders, including biliary cirrhosis, can have asecondary form of hyperlipidemia with associated tuberous and planar xanthomas.However, patients with myeloma have normolipemic flat xanthomas. This latterform of xanthoma may be ≥12 cm in diameter and is most frequently seen on theupper trunk or side of the neck. It is important to note that the most commonsetting for eruptive xanthomas is uncontrolled diabetes mellitus. The least specificsign for hyperlipidemia is xanthelasma, because at least 50% of the patients withthis finding have normal lipid profiles. In tophaceous gout there are deposits of monosodium urate in the skinaround the joints, particularly those of the hands and feet. Additional sites of tophiformation include the helix of the ear and the olecranon and prepatellar bursae.The lesions are firm, yellow in color, and occasionally discharge a chalkymaterial. Their size varies from 1 mm to 7 cm, and the diagnosis can ...