Do More With Less: Tips and Techniques for Maximizing Small Biopsy and Cytology Specimens for Molecular and Ancillary Testing: The University of Colorado Experience

Abstract

Context In an era in which testing of patient tumor material for molecular and other ancillary studies is of increasing clinical importance for selection of therapy, the ability to test on small samplings becomes critical. Often, small samplings are rapidly depleted in the diagnostic workup or are insufficient for multiple ancillary testing approaches. Objective To describe technical methodologies that can be implemented to preserve and maximize tissue for molecular and other ancillary testing. Data Sources Retrospective analysis of a case cohort from the University of Colorado, description of techniques used at the University of Colorado, and published literature. Conclusions Numerous techniques can be deployed to maximize molecular and other ancillary testing, even when specimens are from small samplings. A dedicated process for molecular prioritization has a high success rate, but also increases workload, which must be factored into establishing such a process. Additionally, establishing high-fidelity communication strings is critical for success of dedicated molecular prioritization of samples. Numerous approaches can be deployed for alternative specimen types, and several technical approaches can also aid in maximizing small specimens.

Techniques for maximizing the performance of molecular pathology testing: responsibilities of all pathologists

“…Taking this cross-section as a guide, these areas are scraped from the relevant block ( Figure 1A-D). Macrodissection is sufficient in some large samples, and detailed microdissection may be necessary for specimens that may be considered particularly small and insufficient (3). If the tumor is heterogeneous, it may be necessary to mark multiple sites in multiple locations (4).…”

“…As an alternative to macrodissection, a 1 mm punch can be taken from the marked areas or microdissection can be performed using a tissue counterstain under a stereoscopic microscope. Aisner et al stated that they used a stereoscopic microscope with 10-micron sections for microdissection in their lab and while 3 or fewer consecutive sections were sufficient for microdissection in resection specimens, a larger number of consecutive sections might be required in smaller specimens (3). A laser capture microdissection method is also described (Emert-Buck et al 1996), and manual microdissection methods are being investigated and improved (7).…”

“…is referred, immunohistochemical and histochemical stained smears may provide an additional source of genetic material. If there is more than one material belonging to a patient and it can not be decided which is more appropriate for the molecular tests, it would be appropriate to send all available materials (3). If the pathologist is not familiar with molecular pathological analysis prerequisites, it would be the best practice to send all the available material including cytological samples to a center with molecular pathology facilities.…”

“…The requirements for tumor cell number and mutation percentage differ from method to method but there are minimum requirements and increasing number and percentage correlates with the success of molecular testing as a general rule. The pathologist's view in the past that the primary purpose is tissue diagnosis has changed today to tissue protection as well as tissue diagnosis (3). Errors in tissue management lead to insufficient tissue in addition to the disappointment of the patient and undesirable consequences such as the repetition of invasive procedures and the delay of treatment.…”

Molecular testing on endobronchial ultrasound (EBUS) fine needle aspirates (FNA): Impact of triage

“…11,12 Many have been able to keep pace with the contemporaneous MT panels on small biopsy and cytology specimens, [13][14][15][16][17] while others struggle to achieve the results of their counterparts. 11,12 Many have been able to keep pace with the contemporaneous MT panels on small biopsy and cytology specimens, [13][14][15][16][17] while others struggle to achieve the results of their counterparts.…”