title: Skin of patients with large/giant congenital melanocytic nevi shows increased mast cells.
abstract: Nevocytes (NC) and mastocytes (MC) have different progenitors but share stem cell factor as regulator/activator of NC and for differentiation/proliferation of MC. Both cell types express stem cell factor receptor CD117. We hypothesize that large/giant congenital melanocytic nevi (L/GCMN) may associate with MC hyperplasia. Forty-nine L/GCMN were examined, 12 samples from uninvolved skin of L/GCMN patients and 6 control skin samples studied with Giemsa and immunohistochemistry for CD117 and MC-tryptase. Picrosirius red (PR) was used to assess fibrosis. Digital images were used to count MC/mm(2) using ImageJ software. Western blot (WB) for MC-tryptase in 12 GCMN and 12 non-nevus samples was performed. Analysis of variance (Tukey) and Pearson statistical tests were applied. Increased MCs were observed in nevus tissue (75.1 ± 35.3 MCs/mm(2)) and in uninvolved skin (53.74 ± 27.7 MC/ mm(2)). P  =  0.109 from patients with L/GCMN, compared with controls from individuals without L/GCMN (28.74 ± 8.4 MC/mm(2)); P  =  0.001 supported by results of WB analysis for tryptase. A positive trend toward correlation of MC numbers with fibrosis, assessed by PR staining fell short of statistical significance (r  =  0.245; P  =  0.086); no difference in fibrosis was found between nevus and non-nevus skin from patients with L/GCMN (P  =  0.136). We found a higher density of MC, both in normal-appearing skin and nevus areas of L/GCMN patients, compared with control skin samples from individuals without nevi. Given the abnormal wound healing and allergic reactions described in L/GCMN patients, these findings suggest a potential role for MC in the biology of L/GCMN, making them a potential target for therapeutic intervention.
authors.affiliation: 1  Department of Pathology, Children's Hospital of Pittsburgh, University of Pittsburgh Medical Center, Pittsburgh, PA, USA.
authors.forename: Cláudia M
authors.initials: CM
authors.lastname: Salgado
authors.forename: Randi B
authors.initials: RB
authors.lastname: Silver
authors.forename: Bruce S
authors.initials: BS
authors.lastname: Bauer
authors.forename: Dipanjan
authors.initials: D
authors.lastname: Basu
authors.forename: Lori
authors.initials: L
authors.lastname: Schmitt
authors.forename: Yasmin
authors.initials: Y
authors.lastname: Khakoo
authors.forename: Miguel
authors.initials: M
authors.lastname: Reyes-Múgica
mesh_terms: D000293:Adolescent; D015153:Blotting, Western; D049109:Cell Proliferation; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007223:Infant; D008297:Male; D008407:Mast Cells / Q000276:immunology / Q000473:pathology*; D009508:Nevus, Pigmented / Q000276:immunology / Q000473:pathology*; D012878:Skin Neoplasms / Q000276:immunology / Q000473:pathology*
keywords: CD117; giant congenital melanocytic nevus; mast cell; pruritus; stem cell factor; tryptase