Mitochondrial disorder mimicking rheumatoid disease.

OBJECTIVE: Mitochondrial disorders (MIDs) may manifest phenotypically with a plethora of clinical features, but polyarthralgia and cutaneous lesions are still infrequently reported and recognized as phenotypic manifestations of a MID. CASE REPORT: The patient is a 27-year-old Caucasian female with a history of preterm birth, symptomatic myopathy, and polyarthralgia since infancy, followed by multiple endocrinopathies including pituitary insufficiency, cardiac conduction defects, nephrolithiasis, aseptic chronic pancreatitis and sialadenitis, anemia, hyperlipidemia, and dysmorphic features. The patient reported to have profited from hydrocortisone and long-term chloroquine, but hardly from long-term immunosuppression with various immunosuppressants. The diagnosis MID was established upon the multiorgan nature of the disease, presence of core clinical features of a MID, and a muscle biopsy indicative of a mitochondrial defect. The family history was positive for mitochondrial features in the mother and grandmother from the mother's side.
CONCLUSION: Seronegative and non-destructive polyarthralgia and unexplained cutaneous features mimicking cutaneous lupus should be considered as a phenotypic feature of a multisystem MID (mitochondrial multiorgan disorder syndrome, MIMODS). Mitochondrial metabolic defects may trigger secondary immune reactions. Core clinical features of a non-specific MID with infantile onset include symptomatic myopathy, endocrine abnormalities, cardiac conduction defects, dysmorphism, hyperlipidemia, anemia, and nephrolithiasis.