Myalgia in a Patient with Adult-Onset Asthma with Periocular Xanthogranuloma (AAPOX) due to Myotonic Dystrophy type 2 (P6-8.013)

Abstract

<h3>Objective:</h3> To report a patient with myotonic dystrophy type 2 (DM2) and an adult-onset asthma with periocular xanthogranuloma (AAPOX). <h3>Background:</h3> AAPOX is a rare systemic non-Langerhans histiocytosis, clinically characterized by periocular yellowish plaques, adult-onset asthma, and lymphadenopathy, and pathologically characterized by non-caseating granulomas consisting of foamy histiocytes and Touton giant cells. The etiology of AAPOX is unknown, but recent studies suggested a possible link to IgG4-related disease. Autoimmune diseases occur in up to 30% of myotonic dystrophy type 2 (DM2) patients but concomitant AAPOX and DM2 have never been reported. <h3>Design/Methods:</h3> Case report. <h3>Results:</h3> A 38-year-old man with hyperlipidemia presented with 1.5-year history of progressive bilateral periorbital swelling and periocular yellowish plaques, 1-year history of asthma and exercise intolerance, and 4-month history of rosuvastatin-associated myalgias and difficulty climbing stairs. Periorbital soft tissue biopsy revealed characteristic pathological features of AAPOX. Neurologic examination revealed neither weakness nor clinical myotonia. Family history was significant for bradyarrhythmia requiring pacemaker in his mother and maternal grandfather. The patient’s creatine kinase was elevated at 606 U/L (normal &lt; 308 U/L). HMGCR-IgG was negative. IgG4 level was normal. Electromyography revealed diffuse myotonic discharges and a mild proximal myopathy without fibrillation potentials. A triceps brachii biopsy showed a marked increase of fibers harboring internal nuclei, scattered pyknotic nuclear clumps, and type 1 fiber smallness without granulomas. Genetic testing revealed a heterozygous CCTG repeat expansion &gt; 15,600 base pairs in intron 1 of <i>CNBP</i>, consistent with a diagnosis of DM2. His cardiac evaluation was unrevealing. The patient was treated with prednisone and methotrexate with improvement of his periocular disease. Myalgias persisted despite discontinuation of rosuvastati <h3>Conclusions:</h3> We first report the cooccurrence of AAPOX and DM2. Our finding supports the increased risk of autoimmune diseases in DM2 patients. <b>Disclosure:</b> Dr. Skolka has nothing to disclose. The institution of Shreyasee Amin has received research support from NIH. Dr. Liewluck has nothing to disclose.