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Test Catalog

Test ID: FMEL    
Melanoma, FISH, Tissue

Useful For Suggests clinical disorders or settings where the test may be helpful

This test is intended to be used in conjunction with clinical and pathologic information to aid the pathologist in the differentiation of benign from malignant melanocytic lesions. 

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Melanocytic tumors arising in the skin can present a significant diagnostic challenge. While many lesions can be easily classified as benign nevi or malignant melanoma based on histologic features alone, there is a significant subset of lesions that cannot be clearly defined as either benign or malignant. Because the course of treatment for malignant melanoma relative to benign lesions varies significantly from the time of diagnosis, accuracy, and expediency of the diagnosis are of paramount importance. A (FISH)-based test panel has been developed that can be used as a diagnostic aid in the differentiation of malignant from benign melanocytic lesions.


This test is intended to be used in conjunction with clinical and pathologic information to aid the pathologist in the differentiation of benign from malignant melanocytic lesions.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

An interpretive report will be provided.

Interpretation Provides information to assist in interpretation of the test results

The panel test is considered abnormal if certain parameters are met that have been shown to be observed in malignant melanocytic lesions and within normal limits if these parameters are not met. An abnormal result is not diagnostic of malignancy, nor does a normal result exclude malignancy. The results are intended to be interpreted in the context of the pathologic and clinical findings.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

This test is not approved by the FDA and it is best used as an adjunct to existing clinical and pathologic information.


Fixatives other than formalin (eg, Prefer, Bouin's) may not be successful for FISH assays. Although FISH testing will not be rejected due to non-formalin fixation, results may be compromised.


Paraffin-embedded tissues that have been decalcified are generally unsuccessful for FISH analysis. The pathologist reviewing the hematoxylin and eosin-stained slide may find it necessary to cancel testing.

Supportive Data

FISH analysis was performed on paraffin-embedded tissue samples from 26 histologically nonmalignant nevi (normal) and 29 samples from patients suspected or diagnosed with melanoma based on histologic review.


No abnormalities were identified in the 26 nonmalignant lesions. Of the 29 suspected or diagnosed with melanoma cases, 26 were abnormal for at least 1 of the probes tested and at least 50% of the nuclei exhibited the abnormality. Three cases were considered equivocal since the abnormality was identified in <50% of nuclei.

Clinical Reference Provides recommendations for further in-depth reading of a clinical nature

1. Gerami P, Zembowicz A: Update on fluorescence in situ hybridization in melanoma: state of the art. Arch Pathol Lab Med 2011;135:830-837

2. Gerami P, Mafee M, Lurtsbarapa T, et al: Sensitivity of fluorescence in situ hybridization for melanoma diagnosis using RREB1, MYB, Cep6, and 11q13 probes in melanoma subtypes. Arch Dermatol 2010;146:273-278

3. Morey AL, Murali R, McCarthy SW, et al: Diagnosis of cutaneous melanocytic tumours by four-colour fluorescence in situ hybridisation. Pathology 2009;41(4):383-387

4. Gammon B, Beilfuss B, Guitart J, et al: Enhanced detection of spitzoid melanomas using fluorescence in situ hybridization with 9p21 as an adjunctive probe. Am J Surg Pathol 2012; 36(1):81-88

5. Gerami P, Jewell S, Pouryazdanparast P, et al: Copy number gains in 11q13 and 8q34 are highly linked to prognosis in cutaneous malignant melanoma. J Mol Diagn 2011;13(3):352-358

6. Pouryazdanparast P, Cowen D, Beilfuss B, et al: Distinctive clinical and histologic features in cutaneous melanoma with copy number gains in 8q24. Am J Surg Pathol 2012;36(2):253-264