A 59-year-old tile layer presented with fatigue and one year of progressive skin darkening on his palms and soles. Physical examination showed a smooth tongue with patchy areas of mucosal darkening, as well as hyperpigmented palms and soles.
Laboratory studies showed a hemoglobin level of 9.4 g per deciliter (reference range, 14 to 18), a mean corpuscular volume of 117 femtoliters (reference range, 80 to 94), and mild leukopenia and thrombocytopenia.
What is the most likely diagnosis?
