Interobserver agreement in the histopathological classification of desmoplastic melanomas

Cecilia Lezcano; Marianne Berwick; Li Luo; Raymond Barnhill; Lyn M Duncan; Pedram Gerami; Lori Lowe; Jane L Messina; Richard A Scolyer; Benjamin Wood; Iwei Yeh; Artur Zembowicz; Klaus J Busam

doi:10.1016/j.pathol.2022.12.347

Interobserver agreement in the histopathological classification of desmoplastic melanomas

Pathology. 2023 Mar;55(2):223-226. doi: 10.1016/j.pathol.2022.12.347. Epub 2023 Jan 2.

Authors

Cecilia Lezcano¹, Marianne Berwick², Li Luo², Raymond Barnhill³, Lyn M Duncan⁴, Pedram Gerami⁵, Lori Lowe⁶, Jane L Messina⁷, Richard A Scolyer⁸, Benjamin Wood⁹, Iwei Yeh¹⁰, Artur Zembowicz¹¹, Klaus J Busam¹²

Affiliations

¹ Department of Pathology and Laboratory Medicine, Memorial Sloan Kettering Cancer, New York, NY, USA. Electronic address: [email protected].
² Department of Internal Medicine, University of New Mexico Comprehensive Cancer Center, University of New Mexico, Albuquerque, NM, USA.
³ Department of Translational Research, Institut Curie, Université de Paris UFR de Médecine, Paris, France.
⁴ Pathology Service, Dermatopathology Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA.
⁵ Department of Dermatology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA.
⁶ Departments of Pathology and Dermatology, University of Michigan, Ann Arbor, MI, USA.
⁷ Department of Cutaneous Oncology, H. Lee Moffitt Cancer Center & Research Institute, Tampa, FL, USA.
⁸ Melanoma Institute Australia, The University of Sydney, Sydney, NSW, Australia; Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia; Tissue Pathology and Diagnostic Oncology, Royal Prince Alfred Hospital and NSW Health Pathology, Sydney, NSW, Australia; Charles Perkins Centre, The University of Sydney, Sydney, NSW, Australia.
⁹ Department of Anatomical Pathology, PathWest Laboratory Medicine, Perth, WA, Australia.
¹⁰ Departments of Dermatology and Pathology, University of California San Francisco, San Francisco, CA, USA.
¹¹ Dermatopathology Consultations LLC, Lahey Clinic and Tufts Medical School, Boston, MA, USA.
¹² Department of Pathology and Laboratory Medicine, Memorial Sloan Kettering Cancer, New York, NY, USA.

Abstract

Desmoplastic melanoma is a subtype of melanoma characterised by amelanotic fusiform melanocytes dispersed in a collagenous stroma. Cell-poor and fibrous stroma-rich 'pure' variants have been distinguished from 'mixed' variants with areas of higher cell density and/or less desmoplastic stroma. This distinction is relevant because patients whose tumours display a pure phenotype have a lower risk for regional lymph node metastasis and distant recurrence. However, little is known about interobserver agreement among pathologists in the subclassification of desmoplastic melanoma. To address this issue, we conducted a study in which eleven dermatopathologists independently evaluated whole slide scanned images of excisions from 30 desmoplastic melanomas. The participating pathologists were asked to classify the tumours as pure or mixed. They were also asked to record the presence or absence of neurotropism and angiotropism. We found substantial interobserver agreement between the 11 dermatopathologists in the classification of tumours as pure versus mixed desmoplastic melanoma (kappa=0.64; p<0.0001). There was fair agreement between the 11 dermatopathologists in the evaluation of presence versus absence of neurotropism (kappa=0.26; p<0.0001), and slight agreement in the assessment of angiotropism (kappa=0.13; p<0.0001). The level of concordance in the subclassification of desmoplastic melanomas is encouraging for the acceptance of this prognostic parameter in the real-world practice of melanoma pathology.

Keywords: Desmoplastic; angiotropism; melanoma; mixed; neurotropism; pure.

MeSH terms

Humans
Melanoma* / pathology
Observer Variation
Prognosis
Skin Neoplasms* / pathology

Grants and funding

P30 CA008748/CA/NCI NIH HHS/United States