CDP Melanoma Progression Tissue Microarray (TMA)

The Melanoma Progression TMAs provide researchers with a tissue microarray that includes specimens from different stages of melanoma progression. The TMA is designed to investigate differences in prevalence of markers in various stages of melanoma progression from nevi to malignant melanoma.

The TMA specimen set is a collection of 273 tissue specimens including nevi, primary melanomas and metastatic melanoma, including dermal, lymph node and visceral organ metastasis. The TMAs are constructed from archival, i.e. formalin fixed, paraffin embedded tissue specimens, obtained from patients who were naïve to prior chemotherapeutic/biologic therapy prior to resection of a lesion.

There are four separate arrays-nevi, primary melanoma, melanoma that metastasized to distant sites, and melanoma that metastasized to lymph nodes. Each array is constructed with 1.00 mm cores of tissue, with no core replicates. Normal tissue control cores and several melanoma cell lines established from primary and metastatic melanomas are included in each array. Click Here for the Excel map of sections ^[XLS] or Text alternative for map of sections.

All lesions included in the array were reviewed by three pathologists and met stringent inclusion criteria. A test TMA consisting of a small number of primary and metastatic melanoma lesions for testing a technical approach is also available.

The TMAs were serially sectioned at 6 micron thickness using a "water bath" method and placed on positively charged glass slides. Every 25th section was stained with H&E for histopathology review. These “water bath” sections are at risk for misplaced or lost cores, as well as distortions in orientation and alignment. Additional tissue core loss may occur during the assay procedure, with the rate of loss depending on assay conditions used. Interpretation of TMAs is performed best by a pathologist, who is familiar with the nuances of the melanocytic lesions, immunohistochemistry and interpretation of tissue microarrays. Recommendations for staining the TMAs include a deparaffinization protocol with a minimum of 3 x 5 min in fresh xylene or another de-waxing agent. Microwave-mediated antigen retrieval should not be used. Other harsh antigen retrieval conditions are likely to result in core loss. The melanoma TMA slides, stored under vacuum to prevent their oxidation, are shipped in vacuum-sealed containers. Do NOT open the package until you are ready to stain the slides.

The number of tissue spots in which the desired tissue resides varies from section to section due to the heterogeneity of the specimens. Immunohistological staining with antibodies to several different antigens, known to be expressed in nevi and/or melanomas, was performed by two independent laboratories for beta testing of the TMAs. The results of the analyses showed general concordance with respect to pattern and level of staining, or lack thereof (beta test results are available upon request).

All tissues included in the TMAs were derived from de-identified specimens, and demographic and clinical outcome data are not available. The TMA should be considered a screening array, with interpretation limited to the expression pattern of a selected biomarker in the different stages of melanoma progression.

The TMAs perform adequately for well validated immunohistochemical assays on formalin fixed, paraffin embedded tissue. Although in situ applications are possible, RNA integrity of the tissue cores is not known. The tissue specimens were obtained from multiple institutions, collected over many years. The tissue lacks the uniformity in specimen handling and processing that would be seen in a single institution collection.

Assays that have not been previously performed on formalin fixed, paraffin embedded tissue are not appropriate on these TMAs. The majority of the tissue cores are pigmented and the use of chromogens other than 3, 3' Diaminobenzidine (DAB) should be considered.

To apply for melanoma TMAs from the Cancer Diagnosis Program, please complete an application.

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