Stanford School of Medicine

Surgical Pathology Criteria

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  • Mass forming lesion composed of circumscribed mature adipose tissue and unremarkable thymus

Diagnostic Criteria

  • Circumscribed mass forming lesion
    • Usually over 500 gm
      • Smaller lesions may be found in thymectomy performed for myasthenia gravis
    • May form a discrete tumor in thymus or diffusely enlarge the thymus
  • Predominantly adipose tissue containing interconnecting cords of thymus
    • Thymic tissue is essentially unremarkable with both cortex and medulla
  • Rare variants are reported, with no known clinical difference
    • Thymofibrolipoma
    • Lipofibroadenoma
      • Interconnecting cords of epithelial cells and groups of adipocytes set in a loose fibrous component
      • 2 of 3 reported cases were associated with conventional thymoma
    • One case reported as thymohemangiolipoma
    • Rare cases reported with prominent myoid cells
  • Rare, mean age 20-30
    • May be seen in children
  • Up to 50% in some series are associated with autoimmune disease
    • Myasthenia gravis is most common
      • Also aplastic anemia, hypogammaglobulinemia, lichen planus, Grave disease
      • Diseases and symptoms may improve following resection
  • Benign
  • Differential diagnosis is limited
    • Lipoma is ruled out by the presence of the thymic component
    • Atrophic thymus with adipose replacement is an incidental finding and does not form a mass

Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342

Original posting/updates: 9/24/10

Classification / Lists

Intrinsic Tumors of the Thymus

Miscellaneous Thymic Lesions and Conditions


  • Shimosato Y, Mukai K, Matsuno Y. Tumors of the Mediastinum, Atlas of Tumor Pathology, AFIP Fourth Series, Fascicle 11, 2010
  • Travis WD, Brambilla E, Muller-Hermelink HK, Harris CC eds. World Health Organization Classification of Tumors. Pathology and genetics of tumors of the lung, pleura, thymus and heart. IARC Press: Lyon 2004
  • Moran CA, Zeren H, Koss MN. Thymofibrolipoma. A histologic variant of thymolipoma. Arch Pathol Lab Med. 1994 Mar;118(3):281-2
  • Rieker RJ, Schirmacher P, Schnabel PA, Moser K, Hoffmann H, Dienemann H, Pfannschmidt J. Thymolipoma. A report of nine cases, with emphasis on its association with myasthenia gravis. Surg Today. 2010;40(2):132-6
  • Ogino S, Franks TJ, Deubner H, Koss MN. Thymohemangiolipoma, a rare histologic variant of thymolipoma: a case report and review of the literature. Ann. Diagn. Pathol. 2000; 4; 236–239
  • Gannon BR, Dexter DF, Petsikas D, Isotalo PA. Mediastinal thymolipoma: a rare occurrence with striated myoid cells. Tumori 2007; 93; 198–200
  • Iseki M, Tsuda N, Kishikawa M et al. Thymolipoma with striated myoid cells. Histological, immunohistochemical, and ultrastructural study. Am. J. Surg. Pathol. 1990; 14; 395–398
  • Moran CA, Zeren H, Koss MN. Thymofibrolipoma. A histologic variant of thymolipoma. Arch. Pathol. Lab. Med. 1994; 118; 281–282.
  • Kuo T-T, Shih L-Y. Histologic types of thymoma associated with pure red cell aplasia: A study of five cases including a composite tumor of organoid thymoma associated with an unusual lipofibroadenoma. Int J Surg Pathol. 2001 9: 29-35
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