Nonlipidized juvenile xanthogranuloma: a histologic and immunohistochemical study.

Among all patients with a pathologic diagnosis of juvenile xanthogranuloma (JXG) seen at our institution from 1983 to 1994, we identified five patients with an unusual histologic pattern that differed from the classic juvenile xanthogranuloma (CJXG) with foamy cells and Touton giant cells. Four of these five cases, which we termed nonlipidized juvenile xanthogranuloma (NJXG), were seen in infants. The histologic features include a monomorphic infiltrate with absent or few foam cells and Touton giant cells. There is little inflammation, and mitotic figures are easily found. Four cases exhibit a diffuse sheetlike pattern while one is trabecular. Immunoperoxidase staining was done. All lesions are consistently positive for factor XIIIa as opposed to only focally positive or negative in CJXG and negative in Langerhans cell histiocytosis (LCH). The S-100 was negative. NJXG represents an atypical histologic variant of JXG, which may suggest a malignant or aggressive tumor. The follow-up, however, indicates that these lesions behave in a fashion similar to those of CJXG. The differential diagnosis should be made with LCH, intradermal nevus, and reticulohistiocytosis. The immunoperoxidase findings help to differentiate NJXG from these entities.