Clinical Findings: A 72 years old female visited first dermatology clinic due to a smooth yellow-pink nodule on the right breast. Clinical impression was sebaceous hyperplasia or adnexal tumor. A punch biopsy was performed. The patient was relatively healthy with no significant past medical history.
Pathology Findings: A skin biopsy showed a large amount of pick amorphous amyloid deposition, which pushed down the adnexal structures and perivascular infiltration. Artifactual clefts and detachment of amyloid were characteristic. The most of perivascular infiltrate was plasma cells. Some of those were binucleated. Immunohistochemical studies showed that the infiltrating plasma cells showed kappa light chain monotypic expression and diffuse positivity of aberrant CD20. Infiltrating plasma cells were also positive for CD138, MUM1, and Cd25 and negative for Cd3 and PAX5. Congo Red stain highlighted green birefringence under the polarizing microscopic examination. I recommended a close clinical follow up for the systemic myeloma.
Follow Up: One year later the skin diagnosis, the patient was admitted to The Methodist. The bone marrow aspirate, clot and biopsy showed diffuse monoclonal plasma cell infiltrate with multifocal aggregates (15% of total cell population). Kappa restriction was detected by In situ hybridization. Congo Red stain was negative for the amyloid deposition. After the comprehensive systemic work-up, the patient had received an autologous bone marrow transplantation.