Background:

Graves’ disease which consists of goiter with excessive discharge of thyroid hormones also has important extra thyroid manifestation. Thyroid dermopathy (pretibial myxedema) is an autoimmune phenomenon of Graves’ disease. In fact the extrathyroidal manifestations of this form of thyrotoxicosis are due to immunologically mediated activation of fibroblasts in the extraocular muscles and the skin, with accumulation of glycosaminoglycans, leading to trapping of water and edema. This study highlights the pretibial region changes under light microscopy in known Graves’ disease patients.

Aims:

The aims of this study are to evaluate the prevalence of pretibial myxedema in Graves’ disease and to explore the histopathological features of the pretibial regions.

Materials and methods:

This was an observational study. Thirty consecutive cases of Graves’ disease diagnosed in the endocrinology department and subsequently attending the dermatology OPD of a tertiary care hospital were examined clinically and skin biopsy of the pretibial region was done. Specimens were examined under light microscopy.

Result:

In our study we found 4 patients (13.3%) had frank pretibial myxedema. Among these only 1 patient (25%) had associated exophthalmos. About 12 cases (40%) of all Graves’ disease patients had exophthalmos. The patient with overt pretibial changes was seen to be suffering with Graves’ disease for more than 1 year. Histopathological examination of the area showed flat or atrophic epidermis with prominent dermal edema, separation and fibrosis of dermal collagen. We also found that about 8 patients (26.6%) of those who had Graves’ disease for less than 1 year developed hyperkeratosis and mild fibrosis of dermis on histopathological examination. Both sexes were equally affected by pretibial myxedema (1:1).We also noticed that patients of frank pretibial myxedema had extremely high level of free T4 levels (148-470mg/dl).

Conclusion:

Pretibial myxedema of Graves’ disease is a late manifestation and associated with a very high level of circulating thyroid hormones. It was occasionally preceded by ophthalmopathy.

Keywords: Graves’ disease, pretibial myxedema, exophthalmos