Juvenile xanthogranuloma invading the muscles in the head and neck: clinicopathological case report.

Juvenile xanthogranuloma (JXG) is a member of the non-Langerhans cell group of histiocytic proliferative disorders. It typically presents as a solitary, benign, rapidly growing cutaneous tumor that may regress spontaneously. Most cutaneous lesions of JXG occur in the head and neck region of infants and young children. JXG has been documented in many visceral locations including the lung, bone, testis, gastrointestinal tract, kidney, heart, eye, and oral cavity. Intramuscular location is extremely rare. The few intramuscular lesions that have been described involve the trunk, with the musculature of the back involved most frequently. The authors present a patient with juvenile xanthogranuloma on her chin deeply invading the underlying facial muscles. Histopathological analysis confirmed the intramuscular extension. To the authors' knowledge, this is the first detailed clinicopathological report of juvenile xanthogranuloma infiltrating the muscles in the head and neck.