Collagenous fibroma

Fibroma of tendon sheath and collagenous fibroma (desmoplastic fibroblastoma) are usually sufficiently distinct clinically and histologically to separate them from fibromatosis. They often react either diffusely or focally for muscle-specific actin and smooth muscle actin and may even show faint S-100 positivity.Desmin, however, is not found. In addition to sharing an immunophenotypic profile, fibroma of tendon sheath and collagenous fibroma have been observed to harbor the same abnormality of chromosome... 

Ide F, Shimoyama T, Horie N, et al. Collagenous fibroma (desmoplastic fibroblastoma) presenting as a parotid mass. J Oral Pathol Med. 1999 28 465-468. 

Fibromas are composed mostly of fibroblasts and spindle cells and abundant collagen contents. Fibromas are not hormonally active. Fifteen percent of fibromas are associated with ascites (Fig. 9.32), and in 1% pleural fluid is also found [83]. This triad of an ovarian fibroma, ascites and pleural effusion constitutes the benign Meigs syndrome, which can be associated with elevated Ca-125 levels [84]. In basal cell nevus syndrome, numerous basal cell carcinomas are associated with abnormalities of bones, eyes, brain, and tumors, including ovarian bilateral fibromas [85]. 

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