A case of pleuroperitoneal communication during long-term steroid therapy for dermatomyositis.

Abstract

Dermatomyositis is characterised by inflammation of the muscles that causes muscle weakness, and the muscles proximal to the trunk are most affected. Corticosteroids are mainly used for the treatment of dermatomyositis. We describe an extremely rare case of a patient with dermatomyositis who developed pleuroperitoneal communication (PPC) during long-term steroid therapy. A 60-year-old woman had been diagnosed with dermatomyositis approximately 20 years earlier and remission was maintained on prednisolone 5 mg/day. During the course of treatment, she had developed kidney impairment associated with antiphospholipid syndrome, and her kidney function gradually deteriorated, resulting in initiation of automated peritoneal dialysis (PD) approximately 6 months earlier. Five days before admission to our hospital, she had fallen out of bed and bruised her chest. She developed difficulty breathing and gained weight, in addition to having poor outflow during PD. A plain chest radiography revealed pleural effusion predominantly (Figure 1(a)). Ultrasonography performed after intraperitoneal injection of a contrast agent (perflubutane) showed leakage of contrast into the right thoracic cavity (Figure 1(b)). Accordingly, the patient was diagnosed with PPC. Thoracoscopy confirmed remarkable thinning of the diaphragm with tears and blebs. Intraoperative identification of fistula areas was challenging and dialysate leakage from the peritoneal cavity to the thoracic cavity was observed at several sites (Figure 1(c)). Therefore, PD was discontinued and hemodialysis was started. To date, there have been no reports of onset of PPC after initiation of PD in patients with underlying dermatomyositis. PPC develops within 30 days of initiation of PD in approximately 50% of patients. The frequency of PPC in patients on PD is approximately 1.6–10%. In general, PPC occurs unilaterally and predominantly on the right side. Causes of PPC are reported to include congenital or traumatic factors and bleb laceration. Why did our patient develop PPC? We believe that two mechanisms caused the weakening of the diaphragm in this patient. The first was the dermatomyositis. Approximately 78% of patients with idiopathic inflammatory muscle disease develop a weakened diaphragm. Dermatomyositis also causes perivascular inflammation, which results in degeneration and atrophy of muscle fibre bundles because of inflammation of the intermuscular septum. In our patient, inflammation and muscle atrophy may have been present in the striated muscles of the diaphragm. The second mechanism was the effect of long-term steroid use. The mechanism of steroid-related muscle disorders includes inhibition of proliferation of fibroblasts and synthesis of collagen fibres through insulin-like growth factor signalling. In this way, steroid use can weaken tissues. In our patient, chronic inflammation of striated muscles caused by the dermatomyositis led to degeneration and atrophy of muscle fibres in the diaphragm. Moreover, long-term steroid use may have reduced insulin-like growth factor signalling from fibroblasts, resulting in suppression of cell proliferation in muscle tissues. Finally, a fall triggered the pleuroperitoneal leak. We initially considered pleurodesis as a treatment for PPC. If several agents, such as tetracycline or 50% dextrose, are used when the visceral pleura is in close contact