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

Abstract

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.

Obesity-Associated Lymphedematous Mucinosis: Two Further Cases and Review of the Literature

“…The pathogenesis of this rare condition has not been fully elucidated and, to the best of our knowledge, 22 cases have been reported in the English literature and are summarized in Table 1[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]. Lymphatic stasis, stimulated by the obesity, seems to determine a local hypoxia leading to the accumulation of mucin [4].…”

Obesity-associated lymphedematous mucinosis

“…[3] In 1993, Somach et al reported that pretibial myxedema in euthyroid patients may be histologically different from the pretibial myxedema of hyperthyroidism. [2] Then in 2006, Tokuda et al reported three cases of "chronic obesity lymphedematous mucinosis," [4] where mucin accumulation on the legs accompanying lymphedema had histological findings similar to those reported by reported five cases of obesity-associated lymphedema with mucin accumulation on the legs. They renamed this entity "obesity-associated lymphedematous mucinosis."…”

“…Obesity-associated lymphedematous mucinosis shows epidermal atrophy and disappearance of rete ridges with hyper-orthokeratosis, while pretibial myxedema is not associated with epidermal atrophy. [3,4] Both conditions show varying levels of fibrosis associated with stellate or linear fibroblasts and separation of collagen There is limited information on the treatment of obesity-associated lymphedematous mucinosis as only a few cases have been described. Normalization of thyroid function, topical corticosteroids, plasmapheresis, intravenous immunoglobulin, and octreotide have all been tried in the management of "real" pretibial myxedema, but the approach probably needs to be different for obesity-associated lymphedematous mucinosis.…”

“…[3,4] Dermal mucin accumulation is moderate and occurs in the papillary as well as superficial reticular dermis in obesity-associated lymphedematous mucinosis. In contrast, mucin is abundant in the reticular dermis, particularly in the deeper portions, in pretibial myxedema.…”

Pretibial Myxedema

“…2 The differential diagnoses include scleromyxedema (generalized lichen myxedematosus), scleredema, venous insufficiency, lipodermatosclerosis, lymphedema, obesity, and trauma (Table 1). 2,4,9,10 History of thyroid disease, physical examination, and histologic characteristics help differentiate PM from other conditions that lead to similar pretibial deposition of mucin without thyroid disease. 2 Pretibial myxedema is commonly asymptomatic and has the potential of self resolution with time, so therapy is rarely needed.…”