Tissue resources for clinical use and marker studies in melanoma

Abstract

The adequate procurement and preservation of high-quality tissue specimens from patients with melanoma is a critical clinical issue as patients' tumor samples are now used not only for pathological diagnosis but are also necessary to determine the molecular signature of the tumor to stratify patients who may benefit from targeted melanoma therapy. Tissue resources available for physicians and investigators include formalin-fixed paraffin-embedded (FFPE) tissue and frozen tissue, either preserved in optimal cutting temperature (OCT) media or snap frozen. Properly preserved tissue may be used to evaluate melanoma biomarkers by immunohistochemistry (IHC) with tissue microarray (TMA) technology, to perform genetic and genomic analyses, and for other types of translational research in melanoma.

Fig. 1

H&E-based “trimming” of OCT specimens. Examples of H&E-stained OCT tumor sections before (A and C) and following (B and D) trimming of OCT blocks to maximize tumor cell nuclei and to remove areas of necrosis. Note that circled areas (A and C) were identified for trimming

Fig. 2

Diagram of assembled TMA. Tissue cores of patient’s tumors obtained from formalin-fixed paraffin-embedded (FFPE) donor blocks are placed in recipient TMA block by a tissue arrayer. This process can place dozens of donor tissue cores in one TMA block that can be cut and evaluated on a single microscopic slide

Fig. 3

Frozen tissue preparation. (a) Example of liquid nitrogen cryomold freezing stand (LN₂ Stand). (b) LN 2 stand in ice bucket with liquid nitrogen. (c) Examples of: OCT compound; labeled cryomold; and prepped tissue ready for freezing (not on ice; for demonstration purposes only). (d) Process of rapid freezing of tissue in OCT (partially hardened) using LN₂ stand. (e) Process of rapid freezing of tissue in OCT (fully hardened) using slurry method (see ^{Note 15}). (f) Example of labeled aluminum foil OCT archival sample wrapper. (g) Example of frozen OCT sample just prior to wrapping. (h) Examples of wrapped sample (1) backside and (2) front side. (i) Example of wrapped labeled sample placed in archival cryobox