title: Thymic lymphoid hyperplasia with multilocular thymic cysts diagnosed before the Sjögren syndrome diagnosis.
abstract: BACKGROUND
  Thymic lymphoid hyperplasia is often present with myasthenia gravis as well as other autoimmune diseases such as systemic lupus erythematosus and rheumatoid arthritis. Of the 4 cases of thymic lymphoid hyperplasia associated with Sjögren syndrome that have been reported, no case with a thymic lesion diagnosis that led to the diagnosis of Sjögren syndrome has been reported. We herein report a case of thymic lymphoid hyperplasia with multilocular thymic cysts, diagnosed before Sjögren syndrome.
  
  
  METHODS
  A 37-year-old Japanese woman had an approximate 5-cm anterior mediastinal mass detected by chest imaging. The resected lesion revealed multilocular thymic cysts that were filled with colloid-like material. Histology showed lymph follicular hyperplasia with many epithelial cysts. The epithelium consisted of thymic medullary epithelium, and no epithelial proliferation was seen in the lymphoid tissue. Lymphocytes were composed of an organized mixed population of mature T and B cells without significant atypia. The infiltrated B cells did not reveal light chain restriction or immunoglobulin heavy chain gene rearrangement. After the pathological diagnosis of thymic lesion, tests for the presence of autoantibodies were positive for antinuclear antibodies, rheumatic factor, and anti-SSA/Ro antibodies. The Schirmer's, chewing gum, and Saxon tests showed decreased salivary and lacrimal secretion. Lip biopsy showed focal lymphocytic sialadenitis. The signs and symptoms of Sjögren syndrome had not resolved, without aggravation, 1 year after the thymectomy.
  
  
  CONCLUSIONS
  When a case with thymic lymphoid hyperplasia without myasthenia gravis is encountered, it is essential to consider the presence of another autoimmune disease including Sjögren syndrome.
authors.affiliation: Department of Pathology and Laboratory Medicine, Kanazawa Medical University, 1-1 Daigaku, Uchinada, Kahoku, Ishikawa, 9200293, Japan. hminato@kanazawa-med.ac.jp.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Minato
authors.affiliation: Department of Pathology and Laboratory Medicine, Kanazawa Medical University, 1-1 Daigaku, Uchinada, Kahoku, Ishikawa, 9200293, Japan. ekino@kanazawa-med.ac.jp.
authors.forename: Eriko
authors.initials: E
authors.lastname: Kinoshita
authors.affiliation: Department of Pathology and Laboratory Medicine, Kanazawa Medical University, 1-1 Daigaku, Uchinada, Kahoku, Ishikawa, 9200293, Japan. snakada@kanazawa-med.ac.jp.
authors.forename: Satoko
authors.initials: S
authors.lastname: Nakada
authors.affiliation: Department of Pathology and Laboratory Medicine, Kanazawa Medical University, 1-1 Daigaku, Uchinada, Kahoku, Ishikawa, 9200293, Japan. nojima@kanazawa-med.ac.jp.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Nojima
authors.affiliation: Department of Thoracic Surgery, Kanazawa Medical University, Uchinada, Ishikawa, Japan. dr-ryo@kanazawa-med.ac.jp.
authors.forename: Makoto
authors.initials: M
authors.lastname: Tanaka
authors.affiliation: Department of Thoracic Surgery, Kanazawa Medical University, Uchinada, Ishikawa, Japan. usuda@kanazawa-med.ac.jp.
authors.forename: Katsuo
authors.initials: K
authors.lastname: Usuda
authors.affiliation: Department of Thoracic Surgery, Kanazawa Medical University, Uchinada, Ishikawa, Japan. sagawam@kanazawa-med.ac.jp.
authors.forename: Motoyasu
authors.initials: M
authors.lastname: Sagawa
authors.affiliation: Department of Hematology and Immunology, Kanazawa Medical University, Uchinada, Ishikawa, Japan. iwaharu@kanazawa-med.ac.jp.
authors.forename: Haruka
authors.initials: H
authors.lastname: Iwao
authors.affiliation: Department of Hematology and Immunology, Kanazawa Medical University, Uchinada, Ishikawa, Japan. masatana@kanazawa-med.ac.jp.
authors.forename: Masao
authors.initials: M
authors.lastname: Tanaka
authors.affiliation: Department of Radiology, Kanazawa Medical University, Uchinada, Ishikawa, Japan. doaimari@kanazawa-med.ac.jp.
authors.forename: Mariko
authors.initials: M
authors.lastname: Doai
authors.affiliation: Department of Radiology, Kanazawa Medical University, Uchinada, Ishikawa, Japan. tomoko-t@kanazawa-med.ac.jp.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Takahashi
authors.affiliation: Department of Ophthalmology, Kanazawa Medical University, Uchinada, Ishikawa, Japan. n-shiba@kanazawa-med.ac.jp.
authors.forename: Naoko
authors.initials: N
authors.lastname: Shibata
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008476:Mediastinal Cyst / Q000209:etiology*; D012859:Sjogren's Syndrome / Q000150:complications* / Q000473:pathology*; D013952:Thymus Hyperplasia / Q000209:etiology*