Keratotic vascular papules over the feet: a case of Waldenström's macroglobulinaemia-associated cutaneous macroglobulinosis.

Waldenström's macroglobulinaemia (WM) is a plasma-cell dyscrasia characterized by the monoclonal proliferation of lymphoplasmacytes. A 48-year-old man presented with a 4-year history of multiple painful, hyperkeratotic deep-seated papules over the pressure areas of both soles. He had a 1-year history of Raynaud's phenomenon, intermittent epistaxis, recurrent vomiting, tingling and numbness, and visual disturbances. Histological examination of a skin biopsy found amyloid-like deposits in the upper and mid dermis involving dermal blood vessels, but apart from periodic-acid-Schiff, various stains gave negative results for amyloid. Direct immunofluorescence was positive for IgM antibody. Hence, a diagnosis of WM with cutaneous macroglobulinosis was made. Immunoelectrophoresis found monoclonal IgM kappa antibody, and bone-marrow examination revealed a lymphoplasmacytoid malignancy. The patient's systemic systems were attributed to hyperviscosity syndrome associated with WM and the cutaneous papules were identified as deposits of excess IgM antibodies. The patient received five cycles of chemotherapy, resulting in nearly complete resolution of the skin lesions and systemic symptoms.