Tendon sheath fibroma
The tendon sheath fibroma (tenosynovial fibroma) is a nodular benign neoplasm that often adheres to a tendon or tendon sheath or at least develops in its vicinity. The fingers, especially the thumb, index and middle fingers, are typically affected. The tumor within joints ( knee , elbow , wrist ) has rarely been described.
Epidemiology
The tendon sheath fibroma is usually observed between the ages of 20 and 50, with the age peak being in the 4th decade of life. Men are affected slightly more often than women (3: 2).
clinic
Clinically, it is a mostly small, painless tumor formation with slow growth. However, nerve compression , carpal tunnel syndrome, and pain can occur.
pathology
Macroscopy
Macroscopically , it is a sharply demarcated, lobed or multi-nodular tumor with a size of usually less than 2 cm and almost always less than 3 cm. The cut surface is homogeneously whitish and solid.
histology
Histologically , there are well-circumscribed nodules that are often separated by deep, narrow gaps in tissue. The tumor tissue is usually poor in cells and consists of spindle-shaped fibroblasts or myofibroblasts in a stroma rich in collagen fibers . Scattered elongated, slit-shaped vascular spaces are characteristic. A higher cell density is possible in sections, especially in the edge area of the lesion - the picture here can be similar to that of nodular fasciitis . Usually there are no significant cell atypia or mitoses .
Less common features include the appearance of star-shaped cells, pleomorphic bizarre cells, myxoid transmutation, cyst formation , dense hyalinization, and chondroid or osseous metaplasia .
Immunohistochemistry
Often some of the cell elements show expression of smooth muscle actin . In addition, the tumor cells are vimentin- positive. CD34 positivity has been reported in a few cases . The macrophage antigens CD68 and CD163 can be expressed focally. The markers desmin , S100 and beta- catenin are negative.
Differential diagnosis
The Tendovaginal Fibroma has clinical and histological benign lesions such as tenosynovial giant cell tumor , the Einschlusskörperchenfibromatose , the nodular fasciitis , the desmoplastic fibroblastoma , the palmar and plantar fibromatosis and the benign fibrous histiocytoma be distinguished.
forecast
After surgical removal of the findings, up to a quarter of the tumors recur , sometimes repeatedly. This may be because removal can be difficult due to the adherence of tumor tissue to tendon structures. However, recurrences can usually be controlled by a renewed intervention. There is no metastasis .
