Many pathologic fractures, lumps on the head, elevated serum alkaline phosphatase (ALP) levels, and dental caries are the main characteristics of the rare autosomal dominantly inherited calvarial “doughnut lesions” (MIM 126550). We report the sporadic case of a 16‐year‐old patient who has had 10 pathologic fractures between age 6 weeks and 15 years. An elevated serum ALP level was found at age 11 and skull lumps at age 15; radiography showed frontal and parietal round radiolucencies surrounded by sclerotic bone comparable to doughnuts. Magnetic resonance imaging (MRI) showed skull lesions at an early stage. Because the findings are reminiscent of osteogenesis imperfecta (OI), collagen types I, III, and V were analyzed in fibroblasts and shown to be normal in terms of quantities, proportions, electrophoretic mobility, and thermostability. Thus, this rare syndrome can be distinguished from OI by collagen analysis and MRI of the skull at an early stage, even before palpable skull lesions appear. © 2001 Wiley‐Liss. Inc.