Calcifying aponeurotic fibroma is a rarely seen benign soft part tumor. Throughout the world, from 70 to 80 cases have been reported and in Japan there have been only 6 cases since Keasbey reported the first one in 1953.
Recently we experienced such a case which is reported here.
A 5 -year-old girl visited our hospital with the complaint of a tumor in the area of the left ankle joint after learning of calcification of the area by X-ray at a hospital in her neighborhood.
She had an elastic hard tumor, the size of the head of the little finger, in the anterior distal lateral malleolus of her left foot. The surface was smooth, the margin unclear, and adhesion to skin, mobility, redness and local heat was not found.
In the operative findings, the tumor was about 4.0×2.0×1.5cm in size, yellow-white, elastic soft and adhered tightly to the periosteum of fibula, anterior talo-fibular ligament, anterior tibio-fibular ligament and the capsule of ankle joint. These adhesions were invasive.
In the pathological findings, the tumor mainly consisted of spindle cells like fibroblasts, and these cells were of an interlaced pattern. Focal calcification was present and pathological diagnosis was calcifying aponeurotic fibroma.