Juvenile xanthogranulomas (JXG) is a histiocytic disorder, primarily but not exclusively seen throughout the first two decades of life and principally as a solitary cutaneous lesion. This study is a retrospective clinical and pathologic review of 174 cases documenting the cutaneous and extracutaneous manifestations in patients presenting from the neonatal period to 20 years of age (mean 3.3 years; median 1 year). There was a male predominance (99 male:75 female) in all categories of clinical presentation, but especially notable in the group with multiple cutaneous lesions (12 male:1 female). A solitary cutaneous lesion accounted for 67% of all cases, followed by a solitary subcutaneous or deep soft tissue mass (28 cases, 16%), multiple cutaneous lesions (13 cases, 7%), a solitary extracutaneous, nonsoft tissue lesion (9 cases, 5%), and multiple cutaneous and visceral-systemic lesions (8 cases, 5%). The recorded deaths due to disease included two neonates with systemic JXG who developed hepatic failure and thrombocytopenia and at autopsy had giant cell-neonatal hepatitis in addition to JXG in the liver and other visceral sites. A third death in a 3-month-old boy with a retroperitoneal-pelvic JXG occurred after failure to control severe hypercalcemia. The characteristic Touton giant cell in variable numbers was a consistent feature of the cutaneous lesions; however, these cells were either absent or present in reduced numbers in the various extracutaneous lesions when compared with JXG in the skin. Spindle cells intermingled among the mononuclear cells or forming short fascicles were seen in both cutaneous and extracutaneous lesions. Immunohistochemistry was performed on all extracutaneous lesions, and the constituent cells, regardless of their individual morphologic features, were uniformly positive for vimentin, CD68, and factor XIIIa and negative for S-100 protein and CD1a. It is widely held that JXG is a proliferative disorder of dendrocytes, possibly dermal dendrocytes; thus, its clinical and pathologic similarities to Langerhans cell histiocytosis are not entirely unexpected in light of the most recently proposed international classification of histiocytic disorders, which includes JXG and Langerhans cell histiocytosis together as "dendritic cell-related" histiocytoses.