Tendon sheath fibroma D21.9

Skilled and Copeland, 1949; Chung and Enzinger 1979)

Rare, benign, synovial tumor with myofibroblast differentiation.

Unknown. A reactive, fibrotic process or a real neoplasia is discussed, whereas the described translocations rather suggest a tumorous event.

Occurs in adults, in younger to middle age (between 20 and 50 years). Men are affected 2-3 times as often as women.

Mainly in the area of the fingers and toes; also on wrists and ankles. More rarely, large joints (e.g. knee joints) are affected (Toki S et al. 2017).

Primary subcutaneously located hyalinized, esoinophilic, in tissue tumor masses that can extend into the dermis. The tumor parenchyma constantly alternates between cell-rich and partially myxoid portions. Cellular portions (only slight polymorphism) consist of spindle and star-shaped, fibroblast and myofibroblast cells.

Immunohistology: Tumor cells express alpha smooth muscle actin and vimentin.

A t(2;11)(q31-32q12) aberration and a further chromosomal translocation (t(9:11)(p24: q13-14) were described.

Histological:

• Deep-seated dermatofibroma
• Fibrosarcoma
• Tenosynovial giant cell tumor
• Mucoid dorsal cyst.

1. Baran R, Perrin C (2003) Perineurioma: a tendon sheath fibroma-like variant in a distal subungual location. Acta Derm Venereol 83: 60-61
2. Eckert F, Schaich B (1992) Tendon sheath fibroma. A case report with immunohistochemical studies. Dermatologist 43: 92-96
3. Clever CF, Copeland MM (1949) Tumors of Bone. 3rd edn, Lippincott, Philadelphia, 1949

4. Toki S et al (2017) Fibroma of tendon sheath on the medial side of the knee: a case report. J Med Invest 64:173-176.

5. Zelger B et al (2000) Perineuroma. A frequently unrecognized entity with emphasis on a plexiform variant. Adv Clin Path 4: 25-33