Alteration of mast cell proliferation/apoptosis and expression of stem cell factor in the regression of mastocytoma--report of a case and a serial immunohistochemical study.
BACKGROUND
Spontaneous regression of solitary mastocytoma is a well-described phenomenon, but its mechanism is unknown.


METHODS
Serial-section immunohistochemical analyses were performed on biopsies of a mastocytoma from a Japanese child during the proliferation stage (PS, 7 months of age) and the regression stage (RS, 5 years old).


RESULTS
Mast cell (MC) density in RS was markedly decreased (406 cells/mm2) compared to that in PS (3554 cells/mm2). MCs in RS were larger than those in PS. With proliferative cell nuclear antigen (PCNA) staining, 1.7% MCs were positive in PS, whereas no positive MCs were seen in RS. TUNEL-labeling index (LI) in RS (2.8%) increased 1.5-fold in PS (1.9%). With stem cell factor (SCF) staining, 57% of lesional MCs in RS revealed strong cytoplasmic immunoreactivity, whereas only 9% of MCs were positive in PS. Epidermal SCF reactivity was found as intracellular and intercellular patterns in both PS and RS.


CONCLUSIONS
Loss of MC proliferating activity, an increase in apoptotic MCs, and increased expression of SCF in remaining MCs in RS may play a role in the involution of mastocytomas.
Inoue
Tae
T
Department of Dermatology, Akita University School of Medicine, Akita, Japan. taeinoue@med.akita-u.ac.jp
Yoneda
Kozo
K
Kakurai
Maki
M
Fujita
Sachiko
S
Manabe
Motomu
M
Demitsu
Toshio
T
D017209:Apoptosis; D002455:Cell Division; D002675:Child, Preschool; D005260:Female; D006801:Humans; D020287:In Situ Nick-End Labeling; D007223:Infant; D008407:Mast Cells / Q000378:metabolism* / Q000473:pathology*; D034801:Mastocytoma / Q000378:metabolism* / Q000473:pathology*; D009365:Neoplasm Regression, Spontaneous / Q000473:pathology; D018809:Proliferating Cell Nuclear Antigen; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis; D019089:Stem Cell Factor / Q000096:biosynthesis*
D018809:Proliferating Cell Nuclear Antigen; D019253:Proto-Oncogene Proteins c-bcl-2; D019089:Stem Cell Factor