Calcified leiomyoma of deep soft tissue. Report of a case in childhood.

This report illustrates a calcified leiomyoma of deep soft tissue in the left leg of a 6-year-old boy. The tumour was composed of spindle cells arranged in interlacing bundles, between which were multiple small and large areas of calcification. Tumour cells were positive for vimentin, desmin and smooth muscle actin. Ultrastructurally, the cells showed numerous pinocytotic vesicles and bundles of intracytoplasmic filaments with smooth muscle dense bodies. Only four calcified leiomyomas have been previously reported in the deep soft tissues of limbs. Here we report a new case and suggest a new pathogenetic scheme involving alkaline phosphatase in the origin of these calcifications.