The cutaneous mucinoses are a complex group of dermatologic diseases with local, follicular, or diffuse disease. The diffuse cutaneous mucinoses are remarkable not only for their dermal disease, but also for the numerous systemic manifestations. It is important that the clinical dermatologist be able accurately to diagnose and differentiate scleredema, scleromyxedema, REM, generalized myxedema of hypothyroidism, and pretibial myxedema of hyperthyroidism. Because of the variability of associated systemic manifestations, some with substantial morbidity and mortality, accurate diagnosis is vital for awareness and appropriate management.