Mucous membrane, tongue, and palm and sole involvement are rare. A papular and nodular form of JXG has been described. Juvenile chronic myelogenous leukemia has been observed in association with multiple JXGs, and the incidence is especially high in patients with coexistent neurofibromatosis. A skin biopsy may be performed, both for diagnosis and cosmesis. This will usually consist of complete excision of the papule or nodule.
Early biopsies reveal a dense monomorphous histiocytic infiltrate in the dermis.
Extension into subcutaneous tissue, fascia, and muscle occurs in approximately a third of cases. Older lesions contain foam cells, Touton giant cells, and foreign body giant cells. Old lesions demonstrate fibrosis. The histiocytes contain pleomorphic nuclei and contain irregular dense bodies. Clustered comma-shaped bodies occasionally are observed on electron microscopy, but are not specific.