Sites for an optimal biopsy include the epidermis, papillary dermis, and reticular dermis. The amyloid in NLCA is located in the reticular dermis and clearly differentiates NLCA from other forms of amyloidosis. A shave biopsy or other superficial sample may not include enough reticular dermis to complete the diagnosis. They are eosinophilic and homogeneous when stained with hematoxylin and eosin and viewed with standard optics. When stained with Congo red and viewed with polarized light, deposits exhibit a characteristic and diagnostic green birefringence.
Clinical morphology reflects underlying histology.
Plasma cells, which most likely produce the amyloid, occur within an adjacent and intermingled inflammatory infiltrate. When eosinophilic amyloid material is exposed to potassium permanganate prior to staining with Congo red, the amyloid retains its congophilia, similar to systemic amyloidosis but in contradistinction to secondary amyloidosis. The amino acids of the filament proteins are arranged in a characteristic beta-pleated sheet tertiary structure. Various methods attempt to improve the appearance of the lesions, including topical and intralesional corticosteroids, cryotherapy, dermabrasion, shaving, curettage and electrodesiccation, carbon dioxide laser, and pulsed dye laser. Topical and intralesional corticosteroids and cryotherapy usually are not helpful.