Raccoon eye as the sole presenting sign of AL amyloidosis associated with a low-burden clonal plasma cell neoplasm.

Abstract

Periorbital purpura ("raccoon eyes") is a rare but characteristic clinical finding associated with systemic amyloidosis and plasma cell disorders. It results from increased vascular fragility due to amyloid deposition within vessel walls and may serve as an important diagnostic clue for underlying hematological diseases. We report a 60-year-old woman presenting with recurrent, non-traumatic periorbital purpura as the sole clinical manifestation. Evaluation for an underlying plasma cell disorder revealed elevated serum free lambda light chains and an abnormal kappa/lambda ratio. Serum immunofixation electrophoresis demonstrated an IgA lambda monoclonal gammopathy. Bone marrow evaluation showed borderline plasma cell infiltration (10-12%) with lambda-restricted clonal plasma cells, and Congo red staining confirmed amyloid deposition. The patient had a low serum M-protein level and no CRAB features, lytic bone lesions, or other myeloma-defining events. Therefore, the case was classified as AL amyloidosis associated with a low-burden clonal plasma cell neoplasm. This case highlights that AL amyloidosis may arise from low-tumor-burden plasma cell clones without overt multiple myeloma features and that raccoon eyes may occasionally represent the only presenting sign, allowing early recognition of the underlying plasma cell disorder.