Volume 60, Issue 2 pp. 336-346

Presence of cytogenetic abnormalities in Spitz naevi: a diagnostic challenge for fluorescence in-situ hybridization analysis

Vittoria Martin

Vittoria Martin

Institute of Pathology

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Sara Banfi

Sara Banfi

Institute of Pathology

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Andrea Bordoni

Andrea Bordoni

Ticino Cancer Registry, Locarno, Switzerland

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Sandra Leoni-Parvex

Sandra Leoni-Parvex

Institute of Pathology

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Luca Mazzucchelli

Luca Mazzucchelli

Institute of Pathology

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First published: 23 December 2011
Citations: 18
V Martin, Laboratory of Molecular Diagnostic, Institute of Pathology, Via In Selva 24, 6600 Locarno, Switzerland. e-mail: [email protected]

Abstract

Martin V, Banfi S, Bordoni A, Leoni-Parvex S & Mazzucchelli L
(2012) Histopathology 60, 336–346
Presence of cytogenetic abnormalities in Spitz naevi: a diagnostic challenge for fluorescence in-situ hybridization analysis

Aims: Spitz naevi are difficult to diagnose, because of significant overlap with melanomas. It has been recently demonstrated that the LSI RREB1(6p25)/LSI MYB(6q23)/LSI CCND1(11q13)/CEP6 fluorescence in-situ hybridization (FISH) assay is a reliable tool with which to distinguish benign naevi and melanomas. Little is known about its diagnostic usefulness in Spitz naevi.

Methods and results: We investigated 51 patients with Spitz naevi and long-term median follow-up (8.18 years) with the multicolour FISH probe. Control groups included 11 benign naevi and 14 melanomas. Spitz naevi from 32 (63%) patients did not show cytogenetic abnormalities (FISH−). In contrast, Spitz naevi from 19 (37%) patients showed changes in the investigated loci (FISH+). Spitz naevi with the FISH+ profile showed chromosome X polysomy in 14/18 (78%) patients. All Spitz naevi with the FISH− profile were disomic. All melanomas displayed a FISH+ profile, and 4/11 (36%) showed chromosome X polysomy. No differences in clinicopathological features were detected between Spitz naevi with and without genetic abnormalities.

Conclusions: The presence of gene copy number changes in Spitz naevi as detected by FISH is higher than expected, and Spitz naevi at the genetic level represent a heterogeneous group. The findings of similar cytogenetic alterations in Spitz naevi and melanomas suggest that there should be cautious interpretation of FISH analysis in this setting.

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