title: Solitary form of infantile myofibromatosis: a histologic, immunohistochemical, and electronmicroscopic study of a regressing tumor over a 20-month period.
abstract: We present the repeated clinical, histologic, immunohistochemical, and ultrastructural observations on a cutaneous myofibromatous tumor over a 20-month period. A 6-day-old Japanese female had a solitary tumor on her left wrist at birth. A biopsy was first performed at 16 days of age, when the tumor was likely fully developed. Thereafter, the tumor gradually regressed. A second biopsy was performed at 58 days of age, when the tumor was already in a phase of early regression. Finally, the tumor was resected at 20 months of age, when it was in a phase of late regression. Our study demonstrated that undifferentiated immature histiocytic cells predominated over spindle cells in the first biopsy specimen, but thereafter the former cells decreased or disappeared in parallel with the increase in the latter cells, which showed characteristics similar to myofibroblasts, in regressing lesions. This evidence suggests that the undifferentiated immature histiocytic cells are precursors of the spindle cells. Spindle cells in the phase of early regression also showed many vacuoles and lipid-like droplets in the cytoplasm, even though they actively produced massive amounts of glycogen. These findings also suggest that tumor regression results from cytoplasmic vacuolation and disruption of spindle cells. Our results are considered to demonstrate, for the first time, the clinical and histologic features of the different developmental or regressive phases of infantile myofibromatosis.
authors.affiliation: Department of Dermatology, Institute of Clinical Medicine, University of Tsukuba, Ibaraki, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Iijima
authors.forename: R
authors.initials: R
authors.lastname: Suzuki
authors.forename: F
authors.initials: F
authors.lastname: Otsuka
mesh_terms: D014408:Biomarkers, Tumor / Q000378:metabolism; D005260:Female; D006644:Histiocytes / Q000648:ultrastructure; D006801:Humans; D007124:Immunoenzyme Techniques; D007231:Infant, Newborn; D008854:Microscopy, Electron; D018224:Myofibromatosis / Q000378:metabolism / Q000473:pathology*; D009365:Neoplasm Regression, Spontaneous / Q000473:pathology*; D015388:Organelles / Q000648:ultrastructure; D012878:Skin Neoplasms / Q000378:metabolism / Q000473:pathology* / Q000648:ultrastructure
chemical_list: D014408:Biomarkers, Tumor