SESSION TITLE: Cancer Student/Resident Cases
SESSION TYPE: Medical Student/Resident Case Report
PRESENTED ON: Tuesday, October 28, 2014 at 04:30 PM - 05:30 PM
INTRODUCTION: Patients with myasthenia gravis (MG) frequently undergo computed tomography (CT) of the chest to identify any thymic abnormalities. We present the case of an older woman with myasthenia gravis who underwent imaging and was found to have a thymoma as well as several large calcified masses in the anterior mediastinum. This report discusses her management and the likely etiology of these unusual calcified masses.
CASE PRESENTATION: Our patient is a 74 year-old woman diagnosed with MG on a background of Hodgkin’s disease treated with cobalt chest radiotherapy. CT identified a 2cm calcified lesion in the superior mediastinum, a 4.4cm calcified lesion in the anterior mediastinum, and an adjacent 2.5cm soft tissue mass (Fig. 1a & b). These masses were further characterized on MRI (Fig. 1c & d). PET-CT scan showed calcified masses that were not FDG-avid and a soft tissue mass with mild hypermetabolic activity. The patient underwent a median sternotomy and thymectomy. The thymoma was classified as WHO class AB. Histopathological examination of the other masses revealed calcification and fibrosis that resembled an old granuloma (Fig. 2) .
DISCUSSION: Thymomas are an uncommon heterogenous group of anterior mediastinal tumours usually associated with myasthenia gravis. They appear as round masses with signal intensity (T1-weighted images) on CT/MRI. Macroscopic examination reveals well-defined tumors of solid consistency with regions of hyalinization, fibrosis, granulomas and calcification. Histologically, the WHO classifies thymomas into types A, AB, and thymic carcinoma, which is prognostically important for the patient. While surgery is an option for these patients, recurrences of MG after surgery may suggest an extra-thymic mechanism of autoantibody production. Lymph node calcification has been reported in patients with Hodgkin’s disease previously treated with cobalt radiotherapy. These lesions tend to develop as a necrotic process following radiotherapy. Macroscopic examination reveal coarse, nodular deposits resembling a stippled mulberry-like mass, and usually are circular or oval in shape measuring 3-5cm in diameter. CT imaging after therapy generally shows dense calcifications in the presternal area.
CONCLUSIONS: We presented a 74 year-old woman presenting with several anterior mediastinal masses. After surgery, these masses were identified as a thymoma and several calcified lymph nodes. These findings correspond well with the woman’s past medical history of myasthenia gravis and Hodgkin’s disease treated with cobalt radiotherapy.
Reference #1: Moran CA, Suster S. "Ancient" (sclerosing) thymomas: a clinicopathologic study of 10 cases. Am J Clin Pathol 2004; 121:867-871
Reference #2: De Giuli E, De Giuli G. Lymph node calcification in Hodgkin's disease following irradiation. Acta Radiol Ther Phys Biol 1977; 16:305-313
Reference #3: Vainright JR, Diaconis JN, Haney PJ. Presternal soft tissue calcifications following mediastinal radiotherapy for Hodgkin's disease. Chest 1987; 91:136-137
DISCLOSURE: The following authors have nothing to disclose: Sean Goh, James Lim, Mary Beasley, Raja Flores
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