Loss of mitochondrial SDHB expression: what is its role in diffuse thyroid lipomatosis?

Diffuse lipomatosis of the thyroid gland is a very rare disease, characterized by extensive infiltration of thyroid parenchyma by mature adipose tissue, usually not accompanied by amyloid fibrils deposition. The pathophysiology of adipose tissue infiltration in the thyroid gland remains unknown. We report a clinical case of a diffuse thyroid lipomatosis, whose immunohistochemical study of succinate dehydrogenase - subunit B (SDHB) revealed loss of expression of this protein in the follicular or adipose cells. We detected the presence of a recently described SDHB gene large deletion. Loss of mitochondrial SDHB expression may have a key role in understanding the pathophysiology of thyrolipomatosis, by regulating status of lipid metabolism.