Infantile myofibromatosis is a myofibroblastic tumor of childhood which preferentially arises in the dermis, subcutis, muscle, bone, and occasionally viscera. The disorder is usually divided into two forms, solitary and multicentric type, and the clinical course and prognosis are known to be excellent except case with visceral involvement. It is very unfamiliar in neurosurgical field. The authors present an unusual case of solitary infantile myofibromatosis occurring in right temporal bone in aafour-month-old female infant who underwent surgical excision and showed on excellent clinical course without any other adjuvant treatment. The authors propose that this disease entity should be included in differential diagnosis when neurosurgeons meet infant or child whose radiological appearance is similar to finding described.
Child ; Dermis ; Diagnosis, Differential ; Female ; Humans ; Infant ; Myofibroblasts ; Myofibromatosis* ; Prognosis ; Temporal Bone* ; Viscera

Objective: To investigate the clinicopathological features, diagnosis and differential diagnosis of pediatric myofibroma/myofibromatosis of the soft tissue and bone. Methods: All cases of pediatric myofibroma/myofibromatosis of the soft tissue and bone diagnosed between January 2011 and December 2018 were retrieved from the surgical pathology records in the Department of Pathology, Beijing Jishuitan Hospital, Beijing, China. Clinical and radiological data were collected. H&E and immunohistochemistry were used to examine histological and immunophenotypic features and to make the diagnosis and differential diagnosis. The relevant literature was also reviewed. Results: Twenty-eight cases of pediatric myofibroma/myofibromatosis of the soft tissue and bone were respectively collected. The patients' ages ranged from 2 months to 14 years, with a mean age of 7 years. There were 7 females and 21 males. There were 12 cases located in soft tissue, including the finger (n=9), upper arm (n=1) and foot (n=2). There were 14 cases located in the bone of limb, including the femur (n=8), tibia (n=4), clavicle (n=2), fibula (n=2) and radius (n=1). There were 2 cases of myofibromatosis involving multiple bones. Radiology showed lytic lesions in the bone. The proliferation of spindle-shaped myofibroblasts arranged in fascicles with indistinct eosinophilic cytoplasm and bland nuclei, with no pleomorphism and cytological atypia. The characteristic histologic structure was the biphasic nodular growth pattern with cellular and paucicellular regions. The tumors might arrange in a hemangiopericytoma-like pattern. The stroma varied between dense fibrosis and myxoid changes. The reactive new bone formation and inflammatory cell infiltration also existed. Immunohistochemical study showed that the SMA was positive. The surgical resections were performed. One of the patients had tumor recurrence as a result of 11-month follow-up. Conclusions: The pediatric myofibroma/myofibromatosis of the soft tissue and bone is a very rare benign tumor and has a good prognosis. It has a characteristic morphology and its differential diagnosis from other spindle cell tumors could be made with the immunohistochemical analysis.
Child ; Female ; Humans ; Infant ; Male ; Bone and Bones/pathology* ; Diagnosis, Differential ; Leiomyoma ; Myofibroma/diagnosis* ; Myofibromatosis/diagnosis* ; Child, Preschool ; Adolescent

Actins ; metabolism ; Arm ; Diagnosis, Differential ; Fibrosarcoma ; metabolism ; pathology ; Hamartoma ; metabolism ; pathology ; surgery ; Humans ; Infant ; Lipoma ; metabolism ; pathology ; Male ; Myofibromatosis ; metabolism ; pathology ; S100 Proteins ; metabolism ; Vimentin ; metabolism

Actins ; metabolism ; Desmin ; metabolism ; Diagnosis, Differential ; Female ; Hemangiopericytoma ; metabolism ; pathology ; surgery ; Humans ; Mandibular Neoplasms ; metabolism ; pathology ; surgery ; Middle Aged ; Myofibromatosis ; metabolism ; pathology ; surgery ; Soft Tissue Neoplasms ; metabolism ; pathology ; surgery