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Outcomes for Congenital Melanocytic Naevi (OCOMEN)


Congenital Melanocytic Naevi


Having large congenital melanocytic naevi (CMN) is associated with a psychosocial burden on patients and their parents because of its remarkable appearance and the extra care it may require. Large CMN also pose an increased risk of malignant melanoma or neurocutaneous melanosis. There is a lack of international consensus on what important outcome domains to measure in relation to treatment. This makes it difficult to compare options, to properly inform patients and their parents, and to set up treatment policy for CMN. Therefore, we aim to develop a core outcome set (COS), i.e. the minimum set of outcomes that are recommended to be measured and reported in all clinical trials of a specific health condition. This COS can be used in the follow-up of CMN patients with or without treatment, in clinical research and practice.

Scope of the intended COS

  • Patients: all patients with medium, large and giant CMN. All CMN with a size of 1,5 cm Projected Adult Size (PAS) or larger in the face and 10 cm PAS or larger elsewhere
  • Intervention: interventional treatment (laser, excision or curettage) and conservative treatment (watchful waiting)
  • Study types: case reports, cohort studies, case-control studies, randomized controlled trials, systematic reviews
  • Region: global scope


In the Outcomes for Congenital Melanocytic Nevi (OCOMEN) projects, we follow the recommendations from the Core Outcome Measures in Effectiveness Trials (COMET) initiative and the Cochrane Skin Core Outcomes Set Initiative (CS-COUSIN). This project entails the following: (i) a systematic review to identify the previously reported outcomes in literature; (ii) focus groups with national and international patients and parents to identify patient-important outcomes; (iii) classification of outcomes into outcome domains; (iv) e-Delphi surveys in which stakeholders (patients/parents and professionals) can rate the importance of domains and outcomes; (v) an online consensus meeting to finalize the core outcome domains of the COS (vi) and another online consensus meeting to agree on the outcomes that describe the domains and should be measured in outcome measurement instruments. (vii) A systematic review to identify outcome measurement instruments used for CMN studies, and to evaluate their measurement properties.

Involvement of stakeholders

We involved the following stakeholders: people with CMN, their caregivers and professionals. Professionals were: plastic surgeons, dermatologists, psychologists, neurologists, pathologists and researchers.

Current status

Relevant stakeholders reached consensus on the following domains and outcomes for the COS of care and research:

COS of research COS of care
Domains Outcomes that define the domains Domains Outcomes that define the domains
Anatomy of the skin -Satellite naevi number

-Size of CMN

-Texture of CMN

-Color of CMN

Anatomy of the skin -Satellite naevi number

-Size of CMN

-Texture of CMN

-Color of CMN

Quality of life -Emotional distress Quality of life -Emotional distress
Neoplasms/malignancy -Presence of malignancy Neoplasms/malignancy -Presence of malignancy
Nervous system -Neurological symptoms/signs Nervous system -Neurological symptoms/signs
General adverse events -Wound healing problems

-Scar problems

General adverse events -Wound healing problems

-Scar problems

Pathology -Molecular characteristics

Performing a systematic review to identify outcome measurement instruments used for CMN studies, and to evaluate their measurement properties (in development).


This project is partly funded by the European Academy of Dermatology and Venereology and by Stichting de Merel.

Involved Countries

The OCOMEN research team: Netherlands, Germany and France. Stakeholders participating in this project are from different countries.

Date of updates



  • Welling Oei
  • Anne Fledderus

Project team members

  • Phyllis Spuls
  • Chantal van der Horst
  • Suzanne Pasmans
  • Albert Wolkerstorfer
  • Ida Korfage
  • Marjolein van Kessel

Responsible member of Methods group (as assigned by CS-COUSIN)

  • Dr. Jan Kottner



COUSIN protocol form

Protocol OCOMEN-outcomes describing domains

Published references

1. Fledderus, A. C., Franke, C. J. J., Eggen, C. A. M., van Etten-Jamaludin, F. S., van der Horst, C. M. A. M., Brinkmann, S. J. H., & Spuls, P. I. (2019). Outcomes and measurement instruments used in Congenital Melanocytic Naevi research: A systematic review. Journal of Plastic, Reconstructive & Aesthetic Surgery.
2. Oei, W., Fledderus, A. C., Korfage, I., Eggen, C. A. M., van der Horst, C., Spuls, P. I., Brinkmann, S. J. H., Wolkerstorfer, A., van Kessel, M., & Pasmans, S. (2019). Protocol for the development of core set of domains of the core outcome set for patients with congenital melanocytic naevi (OCOMEN project). J Eur Acad Dermatol Venereol.