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Best practice
The difficulty with measuring the largest melanoma tumour diameter in sentinel lymph nodes
  1. Annelien E Laeijendecker1,
  2. Mary-Ann El Sharouni2,3,
  3. Nikolaos Stathonikos3,
  4. Clothaire P E Spoto4,
  5. Bart A van de Wiel5,
  6. Erik J E Eijken6,
  7. Marijne Mulder7,
  8. Antien L Mooyaart8,
  9. Anna Szumera-Cieckiewicz9,
  10. Daniela Mihic-Probst10,
  11. Daniela Massi11,
  12. Martin Cook12,
  13. Senada Koljenovic13,
  14. Llucia Alos14,
  15. Paul J van Diest3,
  16. Alexander C J van Akkooi15,
  17. Willeke Blokx3
  1. 1 Department of Dermatology, Amsterdam University Medical Center, Vrije Universiteit Amsterdam, Amsterdam, Netherlands
  2. 2 Sydney Melanoma Diagnostic Centre, Royal Prince Alfred Hospital, Camperdown, Victoria, Australia
  3. 3 Department of Pathology, University Medical Center Utrecht, Utrecht, Netherlands
  4. 4 Department of Pathology, Tergooi MC, Hilversum, Netherlands
  5. 5 Department of Pathology, The Netherlands Cancer Institute, Antoni van Leeuwenhoek Hospital, Amsterdam, Netherlands
  6. 6 Laboratory for Pathology East Netherlands (LabPON), Hengelo, Netherlands
  7. 7 Symbiant Pathology Expert Center, Hoorn/Zaandam, Netherlands
  8. 8 Department of Pathology, Erasmus University Medical Center, Rotterdam, Netherlands
  9. 9 Department of Pathology and Laboratory Diagnostics and Department of Diagnostic Hematology, Institute of Hematology and Transfusion Medicine, Maria Sklodowska-Curie National Research Institute of Oncology, Warsaw, Poland
  10. 10 Department of Surgical Pathology, University Hospital Zürich, Zurich, Switzerland
  11. 11 Section of Anatomic Pathology, Department of Health Sciences, University of Florence, Florence, Italy
  12. 12 Department of Histopathology, Royal Surrey County Hospital, Guildford, UK
  13. 13 Department of Pathology, Antwerp University Hospital, University of Antwerp, Antwerpen, Belgium
  14. 14 Department of Pathology, Hospital Clinic de Barcelona, Barcelona, Catalunya, Spain
  15. 15 Melanoma Institute Australia, The University of Sydney, Royal Prince Alfred Hospital, Sydney, New South Wales, Australia
  1. Correspondence to Dr Mary-Ann El Sharouni, Department of Pathology, Utrecht University, Utrecht, Utrecht, Netherlands; m.a.elsharouni{at}umcutrecht.nl

ABSTRACT

Identification of sentinel node (SN) metastases can set the adjuvant systemic therapy indication for stage III melanoma patients. For stage IIIA patients, a 1.0 mm threshold for the largest SN tumour diameter is used. Therefore, uniform reproducible measurement of its size is crucial. At present, the number of deposits or their microanatomical sites are not part of the inclusion criteria for adjuvant treatment. The goal of the current study was to show examples of the difficulty of measuring SN melanoma tumour diameter and teach how it should be measured. Histopathological slides of SN-positive melanoma patients were retrieved using the Dutch Pathology Registry (PALGA). Fourteen samples with the largest SN metastasis around 1.0 mm were uploaded via tele-pathology and digitally measured by 12 pathologists to reflect current practice of measurements in challenging cases. Recommendations as educational examples were provided. Microanatomical location of melanoma metastases was 1 subcapsular, 2 parenchymal and 11 combined. The smallest and largest difference in measurements were 0.24 mm and 4.81 mm, respectively. 11/14 cases (78.6%) showed no agreement regarding the 1.0 mm cut-off. The median discrepancy for cases ≤5 deposits was 0.5 mm (range 0.24–0.60, n=3) and 2.51 mm (range 0.71–4.81, n=11) for cases with ≥6 deposits. Disconcordance in measuring SN tumour burden is correlated with the number of deposits. Awareness of this discordance in challenging cases, for example, cases with multiple small deposits, is important for clinical management. Illustrating cases to reduce differences in size measurement are provided.

  • MELANOMA
  • SENTINEL NODE
  • EDUCATION

https://doi.org/10.1136/jcp-2023-209354

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    Footnotes

    • Handling editor Vikram Deshpande.

    • Contributors AEL: conceptualisation; data curation; formal analysis; investigation; methodology; project administration; roles/writing – original draft. M-AES: conceptualisation; data curation; formal analysis; investigation; methodology; project administration; supervision; validation; visualisation; roles/writing – original draft; writing – review and editing. NS: project administration; resources; software. CPES: investigation; writing – review and editing. BAvdW: investigation; writing – review and editing. EJEE: investigation; writing – review and editing. MM: investigation; writing – review and editing. ALM: investigation; writing – review and editing. AS-C: investigation; writing – review and editing. DM-P: investigation; writing – review and editing. DM: investigation; writing – review and editing. MGC: investigation; writing – review and editing. SK: investigation; writing – review and editing. LA: investigation; writing – review and editing. PJvD: conceptualisation; data curation; formal analysis; investigation; methodology; project administration; resources; supervision; validation; visualisation; roles/writing – original draft; writing – review and editing. ACJvA: investigation; methodology; writing – review and editing. WAMB: conceptualisation; data curation; formal analysis; investigation; methodology; project administration; resources; supervision; validation; visualisation; roles/writing – original draft; writing – review and editing.

    • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

    • Competing interests ACJvA declares advisory board and consultancy honoraria from: Amgen, Bristol-Myers Squibb, Merck-Pfizer, MSD Merck, Neracare, Novartis, Pierre Fabre, Provectus, Sanofi, Sirius Medical and 4SC. ACJvA declares research grants from Amgen and Merck-Pfizer. All other authors declare no conflict of interest.

    • Provenance and peer review Not commissioned; externally peer reviewed.