ISR Autumn Meeting 2016

Best Oral Case

Dr Azhar Abbas
Rheumatology/Respiratory Dept. UCHG

Oral (16A153)

A Rare Rarity:Ectopic Thymoma presenting with Systemic Lupus Erythematosus & Myasthenia Gravis

Author(s)

Azhar Abbas,Eibhlin Higgins,Amina Gsel,Bernadette Lynch,John Carey,Anthony  ORegan,John Paul Doran

Department(s)/Institutions

Rheumatology/Respiratory Dept. UCHG

Introduction

Thymoma is a rare tumour.  Ectopic thymoma accounts for only 4% of all thymomas1.  Thymoma is associated with autoimmunity, in particular MG but can be associated with SLE.  Epidemiological studies suggest that SLE co-occurs with thymoma in 1.5-2% of all cases.2 The presence of ectopic thymoma presenting with both SLE and MG has not previously been described.

Aims/Background

Case Report

Method

A 66-year-old female presented with a six-month history of left sided pleuritic chest discomfort. Investigations revealed a CRP of 26.9mg/L., a large right-sided intra-thoracic mass and a small left pleural & pericardial effusion. An extra-thoracic restrictive physiological defect was present on pulmonary function testing and a 30% drop in FEV1 lying supine was noted.

She was initially diagnosed with coexisting pleurisy and an unrelated lung mass, but she developed progressive polyarthralgia with active tenosynovitis of multiple joints was confirmed on ultrasound.Autoimmune serology: ANA=1280 Homogenous pattern,

A clinical diagnosis of SLE was made and she was commenced on prednisolone 20mg daily with marked improvement in symptoms but flaired after trial of reduction. An 11.5cm extra-pulmonary thoracic mass was resected by thoracotomy.Pathology revealed a thymoma. Subsequent pulmonary function testing demonstrated respiratory muscle weakness as a cause for her restrictive physiology.Clinically she did not have classical features of MG but her PFTs revealed a low sniff nasal inspiratory pressure of 75% and a low mean expiratory pressure of 37% and serological evidence of MG with positive ant-ACH receptor antibodies 12. After the thymoma removal her SLE went into remission and autoantibody titres dropped. Her tenslion test was negative also after the thymoma removal and her PFTs no longer showed a postural drop.

Results

This case illustrates 2 autoimmune conditions occurring in a very unusual manner and this has not previously been reported. Impaired regulation of self-tolerance is felt to account for association of thymona to autoimmune disease. It illustrates the need to consider a thymoma or a thymoma in ectopic sites as an aetiology of a newly disgnosed autoimmune condition in particular SLE and MG.

Conclusions

1.Detterbeck et al FC: Thymic tumours. Ann Thorac Surg 2004, 77:1860-9

2.Boonen A (et al) Rennenberg R, Rheumatology (Oxford) 2000; 39: 1044-1046

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