title: Allelic imbalance in the diagnosis of benign, atypical and malignant Spitz tumours.
abstract: To test the diagnostic usefulness of allelic imbalance (AI) analysis based on routinely paraffin-embedded tissue, a series of 55 benign Spitz naevi, Spitz tumours with uncertain malignant potential, and malignant Spitzoid melanomas was investigated. Laser microdissection was used to ensure representative sampling of lesional cells and to investigate AI in separate tumour areas of four melanomas. AI was found in 2/12 (17%) typical Spitz naevi, 3/9 (33%) atypical Spitz tumours, 12/17 (65%) atypical Spitz tumours suspicious for melanoma and 15/17 (88%) Spitzoid melanomas. Additional immunohistochemical staining for Ki-67 using the MIB-1 antibody revealed positive deeply situated lesional cells in 0/6 (0%) Spitz naevi, 1/8 (13%) atypical Spitz tumours, 5/14 (35%) atypical Spitz tumours suspicious for melanoma, and 7/14 (50%) Spitzoid melanomas, respectively. Two of the melanomas examined for AI in separate tumour areas showed intratumoural genetic heterogeneity. In view of the finding of AI and deeply situated Ki-67 positive cells not only in melanomas but also in Spitz tumours with uncertain malignant potential, these approaches appear to have no direct diagnostic applicability for the distinction between benign and malignant Spitz tumours. Further molecular studies will be required to determine whether Spitz tumours and Spitzoid melanomas are unrelated entities, or whether there is a true spectrum of tumour progression.
authors.affiliation: Department of Pathology, University Medical Centre Nijmegen, Nijmegen, The Netherlands. m.vandijk@pathol.azn.nl
authors.forename: Marcory C R F
authors.initials: MC
authors.lastname: van Dijk
authors.forename: Paul D M
authors.initials: PD
authors.lastname: Rombout
authors.forename: Wolter J
authors.initials: WJ
authors.lastname: Mooi
authors.forename: Fred J J M
authors.initials: FJ
authors.lastname: van de Molengraft
authors.forename: Joannes H J M
authors.initials: JH
authors.lastname: van Krieken
authors.forename: Dirk J
authors.initials: DJ
authors.lastname: Ruiter
authors.forename: Marjolijn J L
authors.initials: MJ
authors.lastname: Ligtenberg
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D022981:Allelic Imbalance; D002648:Child; D002675:Child, Preschool; D004273:DNA, Neoplasm / Q000032:analysis; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D019394:Ki-67 Antigen / Q000032:analysis; D007834:Lasers; D008297:Male; D008545:Melanoma / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology; D018895:Microsatellite Repeats; D008875:Middle Aged; D018332:Nevus, Epithelioid and Spindle Cell / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology; D016612:Paraffin Embedding; D012878:Skin Neoplasms / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology
chemical_list: D004273:DNA, Neoplasm; D019394:Ki-67 Antigen