Two asymptomatic lesions that had been present for 1 year on the left upper chest of a 61-year-old man were excised. Pathologic examination revealed the raised, dark brown medial lesion to be an interdermal nevus; the lateral, light tan lesion with papules (arrow) was a papillomatous interdermal nevus with primary macular amyloidosis.
Two asymptomatic lesions that had been present for 1 year on the left upper chest of a 61-year-old man were excised. Pathologic examination revealed the raised, dark brown medial lesion to be an interdermal nevus; the lateral, light tan lesion with papules (arrow) was a papillomatous interdermal nevus with primary macular amyloidosis.
The cause of amyloid production is not known; a variety of mechanisms may be responsible for the characteristic amyloid deposition patterns of the numerous forms of the disease.
When examined under light microscopy, Congo red–stained amyloid fluoresces a characteristic apple green color; amyloid stains pink with hematoxylin and eosin. Immunoglobulins, particularly IgM and C3 complement, are found in cutaneous amyloid.1
REFERENCE:1. Weedon D. Skin Pathology. Edinburgh: Churchill Livingstone; 1997:359-362.