Steinert's disease or myotonic dystrophy type 1 (MD1) is a multisystemic autosomal-dominant inherited neuromuscular disorder. Some authors have suggested that it is associated with a greater risk of cancer.1–4 We report the case of a patient with undiagnosed MD1 who underwent surgery for 2 synchronous tumors.

The patient was a 73-year-old woman, asymptomatic, followed up for multinodular goiter diagnosed of a follicular carcinoma after biopsy. During staging, a mediastinal mass measuring 3.6cm was revealed (Fig. 1), radiologically consistent with metastasis. The patient had a history of bilateral cataract surgery and basal cell carcinoma. As biopsy of the mediastinal lesion proved impossible, we decided to resect it and to perform a total thyroidectomy. Thus, the patient underwent cervicotomy and partial sternotomy, with successful resection of both lesions. After surgery, extubation was delayed for 48h, due to ventilatory problems. On day 5 post-surgery, the patient developed respiratory failure due to bronchoaspiration requiring orotracheal intubation, which led to right basal pneumonia. After this was resolved, the patient developed generalized hypoventilation, attributed to muscular weakness which prevented withdrawal of mechanical ventilation.

Fig. 1.

Computed axial tomography showing a hypervascular mediastinal mass measuring 3.6cm×2.7cm located in the right paracardiac region (A), and multinodular goiter invading the right thyroid lobe (B).

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The pathology report identified a papillary thyroid carcinoma and a mixed B2/B3 thymoma. Myasthenia gravis was suspected, so corticosteroids and anticholinesterase were initiated, and anti-acetylcholine antibody levels and edrophonium tests were requested. However, the patient did not respond to treatment and the studies were negative.

Electromyography revealed a myotonic myopathic pattern typical of MD1, consistent with the patient's clinical characteristics: baldness, drooping eyelids, early cataracts, muscle weakness, and problems swallowing. The diagnosis was confirmed by the results of the genetic study.

In view of the patient's neuromuscular disease, a gastrostomy tube was placed and a tracheostomy was performed to facilitate intermittent disconnection of mechanical ventilation and aspiration of secretions, with a view to discharge with home respiratory support. Despite these measures, the patient died 1 month after surgery due to respiratory failure associated with difficulties in clearing secretions.

MD1 is characterized by progressive weakness and atrophy of the distal and facial muscles, and is associated with repeated failure of the muscles to relax (myotonias). The subclinical forms of this disease may go unnoticed and diagnosis can be late, triggered in many cases by the appearance of an early cataract5 or after undergoing general anesthesia.

Several clinical cases of tumors in MD1 patient have been reported. The most commonly described cancers are pilomatrixomas, although they can vary widely. To date, only 3 studies have attempted to clarify this possible association. One of these, based on 1658 patients with MD (types 1 and 2) concluded that these patients had a higher risk of endometrial, ovarian, brain, and colon cancer,1 and that the risk was higher in women and patients with MD1.2 Two earlier studies detected an increased risk of thyroid cancer and choroidal melanoma,3 as well as thymoma, gynecological and lung cancers.4