Sjögren Syndrome and Thymic Lymphoid Hyperplasia

Abstract

A 51-year-old man was admitted to the emergency department with complaints of weight loss, anorexia, lack of strength in the shoulder and hip joints, vespertine fever, and sweats. On physical examination, he presented erythematous, descamative, and pruriginous cutaneous lesions on the chest and fingers (Figs. 1, 2). A cutaneous biopsy was performed, indicating a pattern of dermatomyositis. Electromyography showed no evidence of myopathic/ neuropathic involvement. Immunological investigation detected antinuclear (1/160), anti-Ro (3+), and anti-La (2+) autoantibodies in the serum. Antiacetylcholine receptor antibodies were not detected. Steroid therapy was started with clinical improvement.Thoracoabdominopelvic computed tomography scan revealed a slightly lobulated structure, possibly representing a rebound thymic enlargement. The patient underwent total body positron emission tomography scan, which showed tissue densification suggesting hypermetabolic pathology of the thymus and suspicion of malignancy.Thymectomy was performed. On histologic examination, the lesion had solid and cystic areas, composed of lymphoid tissue, with numerous lymphoid follicles with germinal centers, and Hassall corpuscles, some of which showed cystic dilation. The cystic component had a squamous epithelium lining and was filled with amorphous eosinophilic material and abundant cholesterol clefts (Fig. 3). Lymphoepithelial lesions were a striking feature, highlighted by the immunohistochemical staining with keratins (Fig. 4); these results are consistent with thymic hyperplasia with lymphoepithelial sialadenitis-like features.After a 2-year follow-up, patient developed xerostomia and xerophthalmia, and in association with the previous, a Sjögren syndrome diagnosis was considered. Corticotherapy was progressively replaced by azathioprine with an excellent outcome.Thymic hyperplasia's association with Sjögren syndrome is rare, and the mechanism behind this association remains unknown. 1 The few cases reported in the literature that describe the coexistence of autoimmune disease and thymic masses mainly concern systemic lupus erythematosus or myasthenia gravis. [2][3][4] The role of thymectomy remains unknown, and the available data on clinical outcomes of thymectomy are contradictory. 1,3,5 Elucidating the physiological connections could guide therapeutic options and improve our understanding of autoimmunity.