We report 3 cases of a previously uncharacterized form of histiocytosis presenting in early infancy and showing ALK immunoreactivity. The patients presented with pallor, massive hepatosplenomegaly, anemia, and thrombocytopenia. Liver biopsy showed infiltration of the sinusoids by large histiocytes with markedly folded nuclei, fine chromatin, small nucleoli, and voluminous lightly eosinophilic c...

The transcription factor LMO2 is involved in vascular and hematopoietic development and hematolymphoid neoplasia. We have demonstrated that LMO2 is expressed nearly ubiquitously in native and neoplastic vasculature, including lymphatics. LMO2 reactivity is otherwise virtually absent in nonhematolymphoid tissues except in breast myoepithelium, prostatic basal cells, and secretory phase endometri...

A 3-year-old Thai boy suffered from two histiocytoses, Rosai-Dorfman disease (RDD) and juvenile xanthogranuloma (JXG). The patient first presented with massive cervical lymphadenopathy at the age of one year. Biopsy revealed typical RDD; abnormally large CD68- and S-100 protein-positive histiocytes with occasional emperipolesis filled up the sinuses. Two years later, he developed polyuria and p...

Juvenile xanthogranuloma (JXG) is a benign self-limited histiocytic proliferative disorder that usually occurs in early childhood. JXG appears as reddish to yellow, papules, or nodules, and although the head, neck, and trunk are the most frequent locations, it can occur at any body site. However, JXG involving the finger is rare. Histologically, JXG is characterized by an ill-defined, unencapsu...

A 38-year-old woman presented to the emergency room with a 7day history of severe headache, nausea, and vomiting . The neurologic examination was normal. Both CT and MR showed a mass at the foramen of Monro (Fig . 1). The CT appearance was atypical for colloid cyst; therefore, the diagnosis of xanthogranuloma was suggested. The mass was surgically removed , and the final pathologic diagnosis wa...