P39 Treatment of scleromyxedema with intravenous immunoglobulin
Authors: Lin Chung Mun Alice , Cooles Faye A. H , Meggitt Simon J , Griffiths Bridget 
Published: April 2020

Abstract

Background
Scleromyxedema is a rare, idiopathic, generalised mucinosis with a progressive and unpredictable course, and has both cutaneous and systemic manifestations. It typically presents with a diffuse cutaneous papular eruption causing extensive skin tightening which can be severely debilitating and is one of four diagnostic criteria for scleromyxedema. The remaining criteria being evidence of histological mucinosis, presence of an IgG lambda monoclonal gammopathy and the absence of thyroid disease. Due to its rarity and subsequent lack of controlled studies, there remains no current standardised treatment. Relevant literature consists of case studies and series trialling use of a variety of immunosuppressive therapies with varying levels of success. Intravenous immunoglobulin (IVIG) has been shown to be the most effective therapeutic option so far and we report here further success following its use.

Methods
A previously healthy 54-year-old Caucasian woman presented to dermatology with widespread cutaneous mucinous deposits on her entire body with sparing of the anterior chest and abdomen. She was trialled on both topical and oral steroids as well as oral and subcutaneous methotrexate, but all had negligible benefit and her modified Rodnan’s skin score (mRss), an objective assessment of skin thickness, remained significantly raised at 29/51. A punch skin biopsy showed prominent superficial histiocytic mucinosis, and serum electrophoresis revealed an IgG lambda gammopathy, consistent with a diagnosis of scleromyxedema. To complete the diagnostic criteria, she also tested negative for thyroid dysfunction. In terms of systemic manifestations, she later presented with unexplained intermittent dysphagia and occasional reflux, which have previously been reported as common symptoms in 60-90% of patients with scleromyxoedema. Monthly treatment with IVIG at a dosage of 2 gram/kg over 2 days was started.

Results
The IVIG showed marked clinical success and minimal side effects. After four cycles, skin thickening was reversed and her mRss dropped to zero. Mycophenolate mofetil (MMF) (2g daily) was introduced after three months, to allow six-weekly IVIG infusions.

Conclusion
This report further supports the growing literature that IVIG is a safe and effective treatment for scleromyxedema. The underlying mechanism of how it treats scleromyxoedema is yet to be elucidated with only proposed mechanisms so far, such as the neutralisation of pathogenic autoantibodies. It is, however, important to acknowledge that IVIG is very expensive and in limited supply and requires time-consuming administration. To combat these downfalls, we had trialled the potential use of MMF as an IVIG ‘sparing agent’ to optimise patient convenience and reduce cost, without compromising clinical care. Unfortunately, the MMF was only successful for the first few months and was subsequently stopped due to adverse effects. Nevertheless, we still anticipate this work will provide further evidence for the approval of IVIG for the future treatment of scleromyxedema.

Disclosures
C. Lin None. F.A.H. Cooles None. S.J. Meggitt None. B. Griffiths None.