Pretibial Myxedema in a Case of Subclinical Hyperthyroidism: A Rare Presentation

A 52-year-old male patient presented with multiple skin-coloured papules, plaques and nodules on the anterior and posterior aspects of both lower legs for 1 year. On clinical examination, firm, non-pitting, non-tender papules and plaques were present, with some areas showing a peau d’orange appearance [Figure 1a]. The thyroid gland was non-palpable. There were no signs of ophthalmopathy or acropachy. He had no personal or family history of thyroid-related disorders, and he was not currently experiencing any signs of thyroiditis or thyrotoxicosis.

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Figure 1:

(a) Shows firm, non-pitting, non-tender plaques and papules, with some areas showing a peau d’orange appearance over the bilateral leg. (b) Histopathological (haematoxylin and eosin [H&E] ×40) features showing oedematous dermis with sparse collagenous bundles separated by large areas of mucin and scattered fibroblasts with chronic inflammatory cell infiltrates. (c) Alcian blue stain positive for mucin 100×.

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The patient’s thyroid-stimulating hormone (TSH) was low (0.006 IU/mL). His free thyroxine and free triiodothyronine values were within normal limits 1 (2.60 ug/dL and 157.5 ng/dL). His antithyroid peroxidase was raised (565 uL/mL) (reference range: 0–34 IU/mL), anti-TSH receptor antibody 13.66 IU/L (reference range: 0–1.22 IU/L). Blood reports were suggestive of subclinical hyperthyroidism. His other routine investigations were within normal limits. Ultrasonography of the neck was unremarkable. Electrocardiography and 2D echocardiography were within normal limits. Histopathology of lesions showed keratinised stratified squamous epithelium with dermal oedema and sparse collagenous bundles separated by large areas of mucin and scattered fibroblasts with chronic inflammatory cell infiltrates [Figure 1b]. Alcian blue stain showed positivity for mucin [Figure 1c]. A diagnosis of myxoedema with subclinical hyperthyroidism was made.