3. Dermatomyositis and underlying bilateral benign endometrioma

INTRODUCTION: The link between ovarian malignancy and paraneoplastic dermatomyositis is well established. Association with underlying benign ovarian pathology is much less certain, with only scarce case report evidence available. This represents the first case of dermatomyositis with associated bilateral ovarian chocolate cysts. CASE DESCRIPTION: A 45-year-old female presented with classical features of dermatomyositis, with a background of hypertension and non-alcoholic fatty liver disease. She had proximal limb weakness, neck flexor weakness, dysphagia and dysphonia, accompanied by a scaly, erythematous rash over her face, chest, abdomen and lateral thighs. Serum creatine kinase (CK) at presentation was 4923 IU/L. An MRI scan of her thighs showed widespread muscle oedema affecting both legs and the pelvis, including the quadriceps, iliacus and psoas muscles. A punch biopsy of the skin on her thigh showed only post inflammatory pigmentation. Lung volumes were reduced (FEV1 69% predicted). Video fluoroscopy confirmed moderate-severe pharyngeal stage dysphagia. CT scan of the chest, abdomen and pelvis revealed enlarged, unilocular cysts in each ovary, the right cyst measuring 7 cm and the left, 5 cm in maximal diameter. Subsequent transvaginal ultrasound confirmed bilateral unilocular, thick walled cysts with a ground-glass appearance, which would be consistent with benign endometriomas. A further interval ultrasound after 1 month showed no change in their appearance or size. Serum CA125 was 104 kU/L. The patient was treated with 3 pulses of 1g intravenous (IV) methylprednisolone, followed by 2 courses of IV immunoglobulin 2g/kg over 5 days. This was followed by a gradually reducing course of oral prednisolone, starting at 50mg OD PO alongside 15mg weekly of oral methotrexate. She has responded well to treatment, with near normalisation of her objective manual muscle testing scores and normalisation of the serum CK value. Surgery is now planned for a total abdominal hysterectomy and bilateral oophorectomy. DISCUSSION: Extensive investigation has not demonstrated any other underlying malignancy to account for the development of dermatomyositis. Initial limited and unsustained clinical response to IV methylprednisolone prompted further treatment with IV immunoglobulin. Surgical histology results are now awaited to confirm the suspected diagnosis. It will be very interesting to see if surgical removal of the cysts has any impact on the clinical manifestation of disease. KEY LEARNING POINTS: Benign ovarian pathology should not be dismissed as a potential underlying mechanism for development of dermatomyositis. CONFLICTS OF INTEREST: The authors have declared no conflicts of interest.