Chronic obesity lymphoedematous mucinosis: three cases of pretibial mucinosis in obese patients with pitting oedema.

Pretibial mucin deposition on the shins is known as pretibial myxoedema. We report three patients with pretibial mucinosis without thyroid disease. The patients were characterized clinically by morbid obesity and bilateral lower extremity pitting oedema with gradual and painless onset, and that did not involve the feet and ankles. Vesicles, semitranslucent papules or a woody plaque were found on the shins. Histologically, patients showed characteristic features of epidermal atrophy with effacement of the rete ridge pattern, separation of collagen bundles associated with oedema with stellate to linear fibroblasts, upward-running increased capillary and small vessels with haemosiderin deposition, and mucin deposition at the superficial papillary dermis and around the vessels. We propose that the present cases of 'chronic obesity lymphoedematous mucinosis' belong to the clinical entity of pretibial mucinosis.