Effect of formalin fixation on tumour size and margins in head and neck cancer specimens

Abstract

Objectives. To quantify tumour size and margin shrinkage due to formalin fixation in head and neck cancer specimens and determine its effect on tumour staging and margin clearance. Methods. Tumour specimens were measured immediate post-resection and at 24 hours after fixation. Tumour was measured in 2 dimensions and one margin was measured. Shrinkage was categorised as < 10%, 10-20%, and > 20%. Effect of shrinkage on tumour stage and margin clearance were evaluated. Results. A total of 50 specimens were analysed. The tumour AP (Anterior Posterior) and SI (Superior Inferior) measurements showed significant shrinkage with a mean difference of 22.93% and 21.69% respectively. > 20% shrinkage was noted in 78% of AP and 58% of SI measurements. Margins showed a mean difference of 25.61%. 84% of margins demonstrated > 20% shrinkage. In all, 46.7% of T3 and 23% of T2 tumours pre-fixation were downstaged to T2 and T1, respectively, post-fixation. Conclusions. Formalin fixation alone can be responsible for significant shrinkage of tumour and margin dimensions in head and neck specimens. It is suggested that decisions regarding the treatment plan should be made on clinical staging of primary tumour rather than pathological staging. In addition, post-excision pre-fixation margins should be considered for treatment planning.KEY WORDS: head and neck neoplasms, formaldehyde, margins of excision, neoplasm staging RIASSUNTO Obiettivi. Quantificare la riduzione delle dimensioni del tumore e dei margini di resezione conseguente alla fissazione in formalina nei tumori della testa e collo e valutare il suo impatto sulla stadiazione del tumore e lo stato dei margini. Metodi. I pezzi operatori sono stati misurati nell'immediato postoperatorio e dopo 24 ore di fissazione. Sono stati misurati il tumore in due dimensioni ed un margine di resezione. La contrazione è stata classificata come < 10%, 10-20%, > 20%. È stata poi analizzato l'effetto della contrazione sullo stadio del tumore e lo stato dei margini. Risultati. In totale sono stati analizzati 50 casi. Le misure AP (anteroposteriore) e SI (superiore-inferiore) hanno mostrato una riduzione significativa con una differenza media rispettivamente di 22,93 e 21,69%. Una contrazione maggiore del 20% è stata registrata nel 78% delle misure AP e nel 58% delle SI. I margini hanno dimostrato una differenza media del 25,61%. Nell'84% dei casi il margine ha mostrato una riduzione superiore al 20%. Il 46.7% dei tumori classificati pre-fissazione T3 e il 23% dei T2 sono stati classificati dopo la fissazione rispettivamente T2 e T1. Conclusioni. Nei tumori della testa e collo, la fissazione in formalina può causare una contrazione significativa delle dimensioni del tumore e della distanza dal margine di resezione. Suggeriamo che le decisioni terapeutiche si basino sulla stadiazione clinica piuttosto che sulla patologica. Inoltre, i margini dovrebbero essere valutati subito dopo la resezione prima della fissazione.

Non-toxic acid-free glyoxal fixative for veterinary histopathology, immunohistochemistry and molecular analysis

“…13,55 Tissue shrinkage and distortion have been widely reported after NBF fixation as well as texture (tissue "hardening") and color changes are well known by experience from pathologists working with NBF. 2,37,57,77 Particularly, shrinkage and distortion can affect the evaluation of tissue periphery which is relevant for example when evaluating tumor size or margins or when studying skeletal muscle changes. 2,37,57 In addition, color and texture changes can affect post-fixation gross examination at trimming or at teaching lab demonstration of non-fresh organ lesions, warranting the use of alternative fixatives known for not altering much texture and colors, such as Klotz.…”

“…2,37,57,77 Particularly, shrinkage and distortion can affect the evaluation of tissue periphery which is relevant for example when evaluating tumor size or margins or when studying skeletal muscle changes. 2,37,57 In addition, color and texture changes can affect post-fixation gross examination at trimming or at teaching lab demonstration of non-fresh organ lesions, warranting the use of alternative fixatives known for not altering much texture and colors, such as Klotz. 32 However, unsatisfactory results and safety issues, make this issue still unsolved.…”