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Figure 1. Sagittal T1 magnetic resonance imaging scan of the chest wall mass.
Figure 2. Axial T1 magnetic resonance imaging scan of the chest wall mass.
Figure 3. Histological section from biopsy specimen of the chest wall mass shows a predominant population of large polygonal cells and a smaller number of admixed multinucleate Touton giant cells (hematoxylin-eosin, original magnification ×50).
The next day, an incisional biopsy was performed. Histological study of the mass showed a predominant population of large polygonal cells and a smaller number of admixed multinucleate giant cells (Figure 3). Both the mononuclear and multinuclear cells had a moderate to large amount of lightly eosinophilic cytoplasm. The nuclei in the mononuclear and multinucleate cells were slightly enlarged and irregular, but significant hyperchromasia was not present and nucleoli were inconspicuous. The mitotic rate was low at fewer than 2 mitoses per 10 high-power fields. The lesion infiltrated skeletal muscle. Stains for fungi and mycobacteria were negative. The mononuclear and multinucleate cells were strongly positive on a vimentin stain. Actin, desmin, S100, factor VIII, and cytokeratin stains all were negative.
Deep juvenile xanthogranuloma (JXG) is a rare fibrohistiocytic tumor and a less common form of xanthogranuloma (congenital xanthoma multiplex, nevoxanthoendothelioma), accounting for less than 5% of JXG. It occurs in newborns and infants, and is characterized by 1 or more cutaneous nodules, a self-limited course with spontaneous regression, and rare extracutaneous involvement. Neither the cutaneous nor the extracutaneous form of the disease is associated with underlying metabolic disease, lipid abnormality, or a familial incidence.1 Juvenile xanthogranuloma occurs in patients 0 to 5 years of age, and may also occur in adolescents and young adults.
Extracutaneous or deep JXG are reported in deep soft tissue and parenchymal organs. Expected sites of deep JXG include the eye, lung, epicardium, oral cavity, testes,2 central nervous system, liver/spleen, and muscle.3 The differential diagnosis of congenital, anterior chest wall tumors includes rhabdomyoblastoma, neuroblastoma, and primitive neuroectodermal tumor. Prognosis for deep JXG is excellent, as spontaneous regression does occur.4 A chromosomal analysis shows normal karyotype.5
Lesions can range in diameter from a few millimeters to several centimeters and are firm, well circumscribed, and vary from tan to yellow on the cut surface.3- 7
Histological examination reveals sheets of well-differentiated histiocytes with little pleomorphism. The foamy cells have abundant cytoplasm and morphologically variable nuclei with finely dispersed chromatin. Multinucleated cells, including Touton giant cells, are typically present. Mixed inflammatory cell infiltrates may be present along the border of the lesion. Immunohistochemistry is characterized by the absence of 5-100 staining and variable presence of other histiocytic markers.7 The cortical thymocyte antigen, Cdla, is positive, suggesting a dermal "indeterminate" cell lineage.5 Ultrastructure examination shows histiocytes with irregular cell membrane and filiform cytoplasmic projections. Lipid bodies and myelin figures are present and Birbeck granules of Langerhans histiocytoses (histiocytosis X) are notably absent.
The pathogenesis of deep JXG is uncertain, and it is unresolved whether the lesion represents a true neoplasm or an unusual reaction. Both the clinical course of natural involution and the immunohistochemical profile lend support to the theory that JXG represents a benign histiocytic proliferation that is likely to be a reactive process.
Accepted for publication July 30, 1997.
Reprints: Butch M. Huston, MD, University of North Carolina Hospitals, Department of Pathology, 422 Brinkhous-Bullitt Bldg, CB 7525, Chapel Hill, NC 27599-7525.
Radiological Case of the Month. Arch Pediatr Adolesc Med. 1998;152(10):1030. doi: