EXTRA-ACRAL CALCIFYING APONEUROTIC FIBROMA - A DISTINCTIVE CASE WITH 23-YEAR FOLLOW-UP

Calcifying aponeurotic fibroma (CAF) is an unusual but well-characteri zed soft tissue neoplasm that typically involves the digits of childre n and frequently recurs locally. This report describes a case from the subcutis of the lumbosacral region. A 26-year-old man initially prese nted at age 3 and developed three recurrences over a 23-year period ea ch at approximately 8-year intervals (ages 10, 18, and 26). The micros copic findings in all recurrences showed a lobulated, poorly circumscr ibed proliferation of dense fibrous tissue containing epithelioid-like fibroblasts, multinucleated cells, and islands of metaplastic chondro id differentiation with focal calcification. Despite origin from an un usual anatomic site, this case reported herein demonstrates the classi cal morphologic features and clinical history of CAF which showed litt le in the way of morphologic evolution despite 23 years of persistence . The clinical and histologic features helpful in distinguishing CAF f rom infantile fibromatosis and soft tissue chondroma are discussed.