Dermatology Online Journal

Biphasic cutaneous amyloidosis
Ming H. Jih
Dermatology Online Journal 7(2): 15

New York University Department of Dermatology

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History

This 25-year-old Malaysian man, who was evaluated at Bellevue Hospital Medical Center for diffuse cutaneous dyspigmentation of more than twenty years duration. He had recently moved to the United States and was admitted for pulmonary tuberculosis. He was born of a non-consanguinous conception with no cutaneous or other anomalies at birth, and there was no family history of skin disorders. During his childhood, he gradually developed hyperpigmentation of the entire upper and lower extremities as well as of portions of his back and shoulders. The lesions were asymptomatic, and he denied scratching or rubbing the affected areas. There also was no history of any preceding inflammation or trauma to the skin.

Physical Examination

Figure 1	Figure 2

Dyspigmentation consisting of both macular and papular hyper- and hypopigmentation was noted on the extremities with lesser involvement of the shoulders and back. There was sparing of the palms, soles, and oral mucosa.

Laboratory Data

A complete blood count, blood chemistry profile, and coagulation panels were normal. Serum protein electrophoresis did not show a monoclonal spike.

Histopathology

There are nodular aggregates of amorphous, faintly eosinophilic material within the dermal papillae. Metachromasia of this material is noted with a crystal violet stain. A superficial, perivascular infiltrate of small lymphocytes and macrophages containing pigment is present.

Comment

Primary cutaneous amyloidosis is classified into three types: macular, lichen (papular), and nodular. Biphasic amyloidosis is a rare entity characterized by the presence of concurrent lesions of macular and lichen amyloidosis. Both the confluent pigmented plaques with a ripped pattern observed in macular amyloidosis and the dome-shaped, flesh-colored or pigmented papules observed in lichen amyloidosis are present. The macular lesions tend to be distributed on the inter-scapular area and thighs while the papular lesions are most commonly present on the arms and lower legs. The occasional transformation of macular amyloidosis into lichen amyloidosis has been observed.

Histopathologically, the lesions of macular and lichen amyloid are similar with the deposition of amorphous eosinophilic material in the dermal papillae that stains with crystal violet and Congo red. Pigment incontinence and necrotic keratinocytes are often seen in both. However, the papular lesions of lichen amyloidosis can be distinguished by the epidermal changes of orthokeratotic hyperkeratosis, acanthosis, and hypergranulosis. Electron microscopy provides a definitive diagnosis and shows six to 10-nm, rod-shaped, amyloid fibrils present among fibroblasts and macrophages containing melanin in the papillary dermis.

The pathogenesis of cutaneous amyloidosis is poorly understood. However, the amyloid deposits stain positively with antibodies to cytokeratin. The finding of necrotic keratinocytes in proximity to amyloid deposits along with the positive cytokeratin immunostaining has lead to the theory that amyloid deposits may be derived from cytokeratin after keratinocyte death. One proposed mechanism for keratinocyte degeneration is repeated mechanical trauma induced by chronic friction. There are reports in the literature in which macular amyloidosis developed secondary to chronic friction induced by nylon bath sponges, pumice stones, and coconut fibers. However, larger case series have failed to show a correlation between areas subjected to repeated friction and the development of cutaneous amyloidosis. There is a higher incidence of cutaneous amyloidosis in Southeast Asia and South America, which implicates a possible genetic or environmental etiologic factor. Indeed, most previously reported cases of biphasic amyloidosis are from Asia.

Most cases of cutaneous amyloidosis remain chronic and refractory to treatment. Topical glucocorticoids, intralesional gluclcortocoids, dermabrasion, and topical retinoids have been used with varied success.

References

Brownstein MH, et al. Biphasic amyloidosis: link between macular and lichenoid forms. Br J Dermatol 88:25, 1973

Bedi TR, et al. Diffuse biphasic cutaneous amyloidosis. Dermatologica 158:433, 1979

Barnadas MA, et al. Papules in the auricular concha: lichen amyloidosis in a case of biphasic amyloidosis. Dermatologica 181:149, 1990

Eswarammorthy V, et al. Macular amyloidosis: etiologic factors. J Dermatol 26:305, 1999

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