AL amyloidosis manifesting as a vertebral amyloidoma secondary to an unrecognized plasmacytoma expressing cyclin D1 case report.

ABSTRACT

INTRODUCTION: Immunoglobin-related (AL) amyloidosis is the production of amyloidogenic immunoglobulin light chains from clonal plasma cells or, rarely, B-cell lymphomas with plasmacytic differentiation. Amyloid deposition causes progressive end organ destruction with profound morbidity. PRESENTATION OF CASE We present a rare case of a lambda light chain AL amyloidoma localized to a thoracic vertebra of an 87-year-old woman who had a remote history of an unspecified non-Hodgkin B-cell lymphoma (NHL). Our patient presented with upper extremity neuropathy and was found by MRI to have a malignant-appearing lesion throughout the T1 vertebra. Initial biopsy showed amyloid deposition and staging evaluation found localized disease. Prior to planned surgery and radiation the following year, she had worsening neuropathy including multiple falls. Repeat MRI confirmed lesion progression with concern for cord compression. Urgent surgical resection was performed. Histology showed numerous plasma cells with abundant amyloid deposition that was found by amyloid typing to be lambda light chain. An incidental B-cell rich lymphoid aggregate was also seen in a bone marrow fragment that required additional immunohistochemical evaluation, showing the aggregate to be benign while revealing the plasma cells to be positive for cyclin D1. She received localized radiation and has been asymptomatic. DISCUSSION: Amyloidosis and plasma cell neoplasms require appropriate staging evaluation. The cyclin D1-positive plasma cells raises the possibility of the t(11;14)/IGHCCND1 translocation that portends better prognosis and therapeutic response with venetoclax. CONCLUSION: Amyloidomas are uncommon and may present in nearly any site, requiring a high index of clinical suspicion for proper diagnosis.