Classic features of primary systemic amyloidosis (AL amyloidosis) leading to diagnosis of plasma cell myeloma.

The diagnosis of primary systemic amyloidosis, also known as AL (amyloid light-chain) amyloidosis, is often delayed owing to its nonspecific manifestations as well as its rarity. A 64-year-old woman presented with an eight-month history of significant weight loss, anemia, fatigue, and progressive painful cutaneous lesions on her hands, lips, back, perianal, and vulvar area that were originally treated unsuccessfully with antimalarials and systemic corticosteroids. Histopathological examination revealed an amorphous dermis with pale pink material that demonstrated positive birefringence with Congo red staining. Subsequently, the patient underwent a bone marrow biopsy, which uncovered a plasma cell myeloma, the source of her amyloidogenic protein production.