Juvenile xanthogranuloma (JXG) is a benign, self-remitting, non-Langerhanscell (LC) histiocytosis most frequently seen in infants and children.
Epidemiology
JXG is the most common form of non LC histiocytosis. It appears within the first year of life in about 75% of cases.
Etiology
The etiology is unknown.
Localization
Cutaneous lesions are irregularly scattered throughout the skin, and are mainly located on the upper part of the body. The most common extracutaneous manifestation is ocular involvement.
Clinical features
Two main clinical variants can be distinguished: a papular form and a nodularform.
Papular form: most frequent, numerous firm hemispheric lesions, 2-5 mm in diameter, red-brown at first and then yellowish. Associated about 20% of café-au-lait spots of neurofibromatosis. May be related to juvenile chronic myeloid leukaemia.
Nodular form: one or a few lesions, round to oval, 1-2 cm in diameter, high-domed, shiny, translucent, yellowish or red brown.
Histopathology
Early lesions: dense infiltrate of monomorphous, nonlipid containing, macrophages with abundant, slightly eosinophilic cytoplasm.
Mature lesions: foamy cells, foreign body giant cells and Touton giant cells, mainly distributed in the superficial dermis and on the border of the infiltrate. In addition to macrophages and foamy cells, there may be lymphocytes, eosinophils,neutrophils and plasma cells scattered throughout the lesion.
Older lesions: fibrosis replaces the cellular infiltrate.
Immunohistochemistry
Macrophages and Touton cells show a uniform positive staining with CD14, CD68, HAM56 and vimentin, frequent positive staining for factor XIII (markers of dermal dendrocytes).
Negative for S100 protein, CD1a, CD15 (Leu M1).
Genetics
JXG is not linked to any genetic locus, but the association with café-au-lait spots of neurofibromatosis (NF1) and the occasional association with neurilemmomatosis (NF2) suggests that a JXG locus could reside onchromosome 17q11.2 or 22q12.
Prognosis and predictive factors
The lesions disappear spontaneously within 3-6 years. Rare cases of JXG with fatal evolution, probably due to cns involvement or fatal liver disease.
Periodic CBC and peripheral smears would be needed during patient’s first two years of life to rule out juvenile myelomonocytic leukemia.
Epidemiology
JXG is the most common form of non LC histiocytosis. It appears within the first year of life in about 75% of cases.
Etiology
The etiology is unknown.
Localization
Cutaneous lesions are irregularly scattered throughout the skin, and are mainly located on the upper part of the body. The most common extracutaneous manifestation is ocular involvement.
Clinical features
Two main clinical variants can be distinguished: a papular form and a nodularform.
Papular form: most frequent, numerous firm hemispheric lesions, 2-5 mm in diameter, red-brown at first and then yellowish. Associated about 20% of café-au-lait spots of neurofibromatosis. May be related to juvenile chronic myeloid leukaemia.
Nodular form: one or a few lesions, round to oval, 1-2 cm in diameter, high-domed, shiny, translucent, yellowish or red brown.
Histopathology
Early lesions: dense infiltrate of monomorphous, nonlipid containing, macrophages with abundant, slightly eosinophilic cytoplasm.
Mature lesions: foamy cells, foreign body giant cells and Touton giant cells, mainly distributed in the superficial dermis and on the border of the infiltrate. In addition to macrophages and foamy cells, there may be lymphocytes, eosinophils,neutrophils and plasma cells scattered throughout the lesion.
Older lesions: fibrosis replaces the cellular infiltrate.
Immunohistochemistry
Macrophages and Touton cells show a uniform positive staining with CD14, CD68, HAM56 and vimentin, frequent positive staining for factor XIII (markers of dermal dendrocytes).
Negative for S100 protein, CD1a, CD15 (Leu M1).
Genetics
JXG is not linked to any genetic locus, but the association with café-au-lait spots of neurofibromatosis (NF1) and the occasional association with neurilemmomatosis (NF2) suggests that a JXG locus could reside onchromosome 17q11.2 or 22q12.
Prognosis and predictive factors
The lesions disappear spontaneously within 3-6 years. Rare cases of JXG with fatal evolution, probably due to cns involvement or fatal liver disease.
Periodic CBC and peripheral smears would be needed during patient’s first two years of life to rule out juvenile myelomonocytic leukemia.