Effect of feline skin specimen preparation on postexcision and postfixation tissue shrinkage

Abstract

Surgically obtained feline skin-muscle-fascia specimens will significantly decrease in size prior to formalin fixation, resulting in falsely decreased measurements from tumor to tissue margins. Affixing the skin to the fascia does not significantly influence this decrease in margin size in feline tissue specimens at this location.

The Effect of Specimen Preparation on Post‐Excision and Post‐Fixation Dimensions, Translation, and Distortion of Canine Cadaver Skin‐Muscle‐Fascia Specimens

“…Twenty canine cadavers were used. A subcutaneous tumor model was created by implanting a gelatin sphere (28 mm) in the subcutaneous space. Gelatin powder (3.6 g, Knox unflavored gelatin, Kraft Foods Global Inc, Northfield, IL) was placed in ¼ cup boiling water, followed by ¼ cup cold water with 2–3 drops of methylene blue dye added (1% Methylene blue, 10 mg/mL; Akorn, Inc., Lake Forest, IL), poured into the mold, and allowed to gel for at least 12 hours in a refrigerator before use.…”

Reductions in margin length after excision of grade II mast cell tumors and grade I and II soft tissue sarcomas in dogs

“…Locally invasive malignancies are frequently treated by surgical excision, which improves clinical outcomes when histologically tumor‐free margins (HTFMs) are achieved . Recent studies have provided preliminary insight into the relationship between HTFM and intraoperative, en bloc excised, grossly normal surgical margins (GNSMs) . Improving our understanding of this relationship is central to creating an evidence‐based rationale for surgical planning and GNSM resection and is tightly coupled to patient morbidity and/or mortality …”

“…The latter is explained by microscopic infiltration of the GNSM, resulting in a narrower HTFM . Other relevant prior publications tested length reductions in normal (ie, non‐neoplastic) tissues, and may therefore not apply to tumor‐bearing specimens; in addition, retrospective studies have not been able to determine at which point of tissue processing did these changes occur …”

“…17 Other relevant prior publications tested length reductions in normal (ie, non-neoplastic) tissues, and may therefore not apply to tumor-bearing specimens; in addition, retrospective studies have not been able to determine at which point of tissue processing did these changes occur. [7][8][9][10][11][12]18,19 The present report builds upon the previously mentioned pilot study by including a larger patient population affected by the 2 most common cutaneous and subcutaneous malignancies of dogs: grade II or "low" grade mast cell tumors (MCT) and grades I and II soft tissue sarcomas (STS). 4,15,[20][21][22] The specific objective was to quantify the changes in circumferential lengths of surgical margins of surgically resected canine MCT or STS at specific processing steps, from intraoperative measurements through histopathologic evaluation.…”

“…Recent studies have provided preliminary insight into the relationship between HTFM and intraoperative, en bloc excised, grossly normal surgical margins (GNSMs). [7][8][9][10][11][12] Improving our understanding of this relationship is central to creating an evidence-based rationale for surgical planning and GNSM resection and is tightly coupled to patient morbidity and/or mortality. 13,14 A pilot study of excised feline injection site sarcomas in cats found that margin length changes occurred at 2 time points: (1) immediately following excision, prior to formalin fixation and (2) between subgross evaluation and microscopic evaluation of the same slide.…”