Elephantiasic Pretibial Myxedema with Involvement of the Buttocks and Face.

To the Editor: Pretibial myxedema (PTM), a localized thyroid-associated dermopathy, is characterized by local thickening and remodeling of the skin − it is often associated with a group of autoimmune thyroid diseases (ATDs).[1] PTM is most frequently located across the lower legs, especially the pretibial areas or the dorsum of the foot. Rarely, the fingers and hands, elbows, arms, or face are affected. Here, we report an unusual case of PTM and vitiligo, involving buttocks and face.

A 58-year-old woman, with a 9-year history of hyperthyreosis exophthalmos and a 15-year history of vitiligo, presented with multiple reddish firm nodules and large hypertrophic plaques on the lower extremities, dorsum of the feet, and the buttocks bilaterally [Figure 1a and 1b]. Irregular depigmented patch was visible on the back of the thorax, the right upper extremity, and the dorsum of the hands and fingers. A single nodule was present on the left side of the patient's face [Figure 1c]. The serum levels of thyroid-stimulating hormone receptor antibodies were >40.0 U/L (normal range <2.5 U/L). Thyroid ultrasonography revealed a diffuse lesion inside the thyroid gland. Histopathological examination using the Alcian blue stain revealed mucin deposition in the reticular dermis with connective tissue separation [Figure 1d]. A diagnosis of elephantiasic PTM with hypothyroidism (post-treatment of radioactive iodine therapy for hyperthyreosis) and thyroid-associated ophthalmopathy was made. The patient was treated with a topical corticosteroid and oral levothyroxine sodium (150 μg, once a day). Thyroid hormone levels returned to normal 1 month later. Most of the nodules and plaques have almost flattened 5 months later [Figure 1e and 1f]. No recurrence was observed during an 8-month follow-up.

Figure 1

Clinical and pathological images of the case: (a) Large firm hypertrophic plaques on the lower extremities and dorsum of the feet. (b) Large firm nodules on the buttocks, bilaterally, and an irregular depigmented patch on the back. (c) A single pink nodule present on the left side of the face. (d) Histopathological examination confirms pretibial myxedema (Alcian blue staining, original magnification ×10). (e) Nodules on the buttocks partially reduced 5-month post-treatment. (f) Plaques on the lower extremities have almost flattened 5-month post-treatment.

It is believed that autoimmune reactions (humoral and cell-mediated immunity) to autoantigens result in excessive hyaluronan deposits and fibrous tissue hyperplasia, causing lesions of PTM to enlarge and protrude rapidly over the skin.[2] The buttocks and face are unusual sites for deposition of mucin. Colucci et al.[3] reported patients with PTM who presented with erythema and thickening of the forehead or localized myxedema on the nasal dorsum. Vitiligo is a pigmentary disorder strongly associated with ATD. A growing body of evidence shows that autoimmunity and oxidative stress interact closely to determine the rate of melanocyte loss. In this scenario, associated ATD might play an active and important role in triggering and maintaining the depigmentation process of vitiligo.[4]

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Financial support and sponsorship

This work was supported by a grant from the National Natural Science Foundation of China (No: 81371731).

Conflicts of interest

There are no conflicts of interest.