This article describes the clinical and pathologic features of four unusual bone tumors. Three were congenital or most likely so; the fourth, detected at age 1 year, was probably of considerable duration. The patients, three boys and one girl, each presented with a painless mass. Two had the Carney complex, a familial lentiginous and multiorgan tumorous syndrome; another probably had this disorder; the fourth did not show it, but his mother did. The tumors occurred in the nasal region (n = 2) and the diaphysis of the tibia and radius (n = 1 each). Roentgenographically, three had benign characteristics; the fourth, malignant features. Grossly, the tumors were gelatinous, cartilaginous. and bony. Microscopically, they featured benign-appearing polymorphic cells with few division figures arranged in sheets and lobules set in a myxomatous, cartilaginous, osseous, and hyaline fibrous matrix. Cellularity was low to moderate. The tumors eroded bone, one infiltrated between bony trabeculae, and three had soft tissue extension. Complete resection of one tumor was curative; incomplete excision of two tumors resulted in local recurrence (intracranial and fatal) in one and persistence in the other; the fourth tumor remains under observation after biopsy. No tumor metastasized.