Original Articles: Miscellaneous: PDF OnlyProgressive Osseous Heteroplasia in Male Patients: Two New Case ReportsRosenfeld, Samuel, R.*; Kaplan, Frederick, S.**Author Information *From Department of Orthopaedic Surgery, University of California, Irvine, Orange, CA. **Department of Orthopaedic Surgery. The University of Pennsylvania School of Medicine, Philadelphia, PA. Reprint requests to Frederick S. Kaplan, MD, Division of Metabolic Bone Diseases, Department of Orthopaedic Surgery, Hospital of the University of Pennsylvania, Silverstein Two, 3400 Spruce St, Philadelphia, PA 19104. Received: November 30, 1994. Revised: February 8, 1994. Accepted: February 27, 1994. Clinical Orthopaedics and Related Research: August 1995 - Volume 317 - Issue - p 243-245 Free Abstract Progressive osseous heteroplasia is a rare developmental disorder of mesenchymal differentiation characterized by cutaneous osteomas in infancy and by progressive heterotopic intramembranous ossification of skin and deep connective tissue. To date, typical features of the disorder have been reported only in 8 female patients. This report documents progressive osseous heteroplasia in 2 boys and has important implications for the clinical detection and pathogenetic understanding of this rare disorder. © Lippincott-Raven Publishers.