Marrow myxedema. Gelatinous transformation of marrow ground substance in a patient with severe hypothyroidism.

Replacement of marrow ground substance by hyaluronic acid-rich mucopolysaccharides (gelatinous transformation) has been previously reported to occur in severely malnourished patients. A patient with severe anemia and hypothyroidism without malnutrition was found to have gelatinous transformation of the marrow. This process is similar histologically to dermal myxedema, and the findings in this patient suggest questions for further study involving possible roles for thyroid-stimulating hormone in the development of marrow and visceral myxedema and the alterations in the normal partitioning process between serum and red blood cell low-density lipoproteins that produce acanthocytes in blood smears from patients with hypothyroidism.