Calcifying aponeurotic fibroma (CAF) is a rare, locally aggressive fibroblastic lesion that occurs predominantly in the distal extremities of children and adolescents.
CAF occurs in patients over a wide age range; however, it is most common in children and adolescents . The median ages for male and female patients are 11 and 12 years, respectively.
CAF grows in a diffuse, poorly circumscribed manner and is often attached to the aponeurosis, tendons or fascia. Complete local excision is the treatment of choice.
The histological examination of the lesion reveals two components:
i) Fibromatosis-like spindle-shaped cell elements, and ii) nodules of calcification, accompanied by more rounded, epithelioid cells.
Two phases have been described in the development of CAF ; in the initial phase the tumor has an infiltrative growth and often lacks calcification, whilst in the later phase the tumor is more compact and nodular and exhibits a more prominent degree of calcification and cartilage formation, as seen in the present case.
The pathogenesis of CAF remains uncertain; however, a fibroblastic/myofibroblastic origin has been suggested . It has been previously demonstrated using immunohistochemistry that the tumor cells usually express vimentin and smooth muscle actin, but are negative for desmin , and these results are in accordance with this proposal.
Source: NISHIO J, INAMITSU H, IWASAKI H, HAYASHI H, NAITO M. Calcifying aponeurotic fibroma of the finger in an elderly patient: CT and MRI findings with pathologic correlation. Experimental and Therapeutic Medicine. 2014;8(3):841-843. doi:10.3892/etm.2014.1838.