The calvarium constitutes the upper part of the cranium and is a well-recognized site of involvement for various pathologic conditions. Among numerous disease processes affecting the skull, metabolic disorders may manifest as diffuse lesions that can challenge diagnosis due to varied appearances and overlapping imaging features. Although not so common, categories of systemic disease associated with calvarial involvement may include rickets, hyperparathyroidism, renal osteodystrophy, acromegaly, amyloidosis, Paget’s disease, phenytoin-induced hyperostosis, chronic anemia, osteopenia, thalassemia, and osteopetrosis. Familiarity with the complex metabolic abnormalities affecting the skull, however, is important in their recognition as a potential source of symptoms related to generalized disease. This chapter provides detailed medical information regarding a wide spectrum of metabolic disorders of the calvaria (and the scalp) and illustrates the characteristic imaging appearances of the major pathologic conditions involving these structures.