Histopathologic maturation of juvenile xanthogranuloma in a short period

We present a case of solitary juvenile xanthogranuloma (JXG) on the scalp of an 8-month-old girl. The initial biopsy specimen showed a dense collection of small histiocytes as evidenced by CD68 staining without either lipidization or giant cell formation, admixed with a small number of lymphocytes. On the other hand, sections from the excised specimen obtained 2 weeks after the initial biopsy from the same site showed a mixed proliferation of abundant foam cells together with Touton giant cells, some small histiocytes, and small numbers of lymphocytes and eosinophils. Mitotic figures were fewer in the excised nodule than in the initial biopsy specimen. Fascicles of spindle-shaped cells arranged in a vague storiform pattern were additionally found in the deep portion of the nodule. Our case findings suggest that xanthomatization of the JXG could have been accelerated by the inflammation associated with the biopsy, based on the histopathologic fact that the change from an early phase to a mature form occurred within the very short period of 2 weeks.