Case Reports
A 67-year-old Japanese man was referred to our department with numerous papules and nodules on the trunk and extremities, without any subjective symptoms (Fig. 1a ). The patient did not experience fever, hepatosplenomegaly, or systemic lymphadenopathy. The complete blood cell count indicated mild anemia and no atypical lymphocyte in the peripheral blood. A biochemical blood test revealed a high β2-microglobulin level of 4.2 mg/L (normal range: 0.8 to 1.8) and high immunoglobulin M level of 2,928 mg/dL (33 to 190), represented as a monoclonal peak by electrophoresis. The examination also disclosed mild abnormalities of the coagulation/fibrinolysis system including factor X, 40% (70 to 130); fibrin/fibrinogen degradation products, 9 μg/mL (0 to 5); and plasmin-α2 plasmin inhibitor complex, 2.8 μg/mL (0 to 0.8). Flow cytometric analysis of bone marrow showed T-cell dominants. Histopathological examination of the skin revealed an amorphous substance around vessels in the dermis and subcutis (Fig. 1b and 1c ), which was highlighted in an orange color (Fig. 1d ) and apple-green-birefringence (Fig. 1e ) by direct fast scarlet staining and polarization, respectively. Histopathological examination of the bone marrow revealed mild proliferation of lymphocytes, plasmacytes, and lymphoplasma cells with Dutcher’s bodies without atypia (Fig. 1f and 1g ), and the presence of CD20-positive cells (Fig. 1h ). A diagnosis of AL amyloidosis due to WM was made.