Deep juvenile xanthogranuloma. Subcutaneous and intramuscular forms

Area of Science:

• Pediatric Pathology
• Dermatopathology
• Soft Tissue Tumors

Background:

• Juvenile xanthogranuloma (JXG) typically affects the skin and eyes.
• JXG involvement of deep soft tissues is exceptionally rare.
• Limited literature exists on deep soft tissue JXG in children.

Purpose of the Study:

• To describe the clinical, histological, and immunohistochemical features of deep juvenile xanthogranuloma (DJX) in pediatric soft tissues.
• To aid in the differential diagnosis of rare soft tissue tumors in children.
• To report long-term follow-up data for these rare lesions.

Main Methods:

• Case series of three pediatric patients with DJX in soft tissues.
• Histopathological examination including routine stains.
• Immunohistochemical analysis for markers of differentiation (HAM-56, HHF-35, vimentin, S-100, MAC-387, factor XIIIa).
• Electron microscopy in one case.

Main Results:

• Three solitary DJX lesions occurred in superficial skeletal muscle, scalp subcutis, and forehead subcutis.
• Grossly, lesions were firm and tan-yellow; histologically, they showed sheets of uniform cells with occasional eosinophils and rare Touton giant cells.
• Immunohistochemistry and electron microscopy supported macrophagic-myofibroblastic differentiation; S-100 and other markers were negative.
• No recurrences were observed after 5-7 years of follow-up.

Conclusions:

• Deep juvenile xanthogranuloma is a rare entity in pediatric soft tissues.
• Immunohistochemical and ultrastructural findings support a macrophagic-myofibroblastic origin.
• DJX should be considered in the differential diagnosis of pediatric soft tissue tumors, alongside deep fibrous histiocytoma and cellular subcutaneous neural tumors.