Multiple myeloma initially manifesting as a solitary deep ulcer on the tongue: a case study and literature review.

Multiple myeloma (MM) is a malignant disease associated with clonal plasma cell proliferative disorder, characterized by extensive infiltration of clonal plasma cells in the bone marrow, for which a proportion of patients suffer poor outcome and exhibit no obvious symptoms in the early stages. Amyloidosis is a rare condition caused by MM. Immunoglobulin light chain amyloidosis (AL) is caused by the secretion of specific toxic light chain proteins from proliferating clonal B cells or plasma cells. These light chain proteins accumulate in human tissues and cause organ dysfunction and failure. Oral manifestations of amyloidosis include macroglossia, prominent lingual margins, coloured papules, purpura, and nodular protrusions. To describe and summarize the oral manifestations associated with AL amyloidosis in order to achieve an accurate clinical diagnosis. We present a case of AL amyloidosis associated with multiple myeloma and review the literature on other related cases identified from the inception of Medline. A female patient visited our clinic with a deep tongue ulcer. After oral biopsy and tissue staining, combined with the examination results from the Department of Haematology, the patient was diagnosed with oral AL amyloidosis related to multiple myeloma. This is the first case study of AL amyloidosis secondary to latent MM presenting as a solitary tongue ulcer. Chronic oral refractory ulcers may be associated with systemic diseases and should be considered in future clinical practice.