Multiple blue-black macules post-COVID
Last reviewed: December 2024
Author(s): Dr Selene Ting, Dermatology Registrar, New Zealand (2024)
Reviewing dermatologist: Dr Ian Coulson (2024).
Edited by the DermNet content department
Background
A 51-year-old Tongan woman with a background of chronic plaque psoriasis controlled on 20 mg weekly of methotrexate, presented for a routine review and was noted to have multiple asymptomatic blue-black macules and papules scattered on her face, forearms, trunk, and feet. She reported having had a couple of these lesions for years before a marked increase in number following a serious infection of SARS-CoV-2 (COVID-19) a year prior to her presentation. Dermoscopy of a representative lesion is shown.
What is the diagnosis?
Eruptive blue naevi.
A typical blue naevus is a small, solitary, well-defined blue, blue-grey, or blue-black macule or papule that becomes evident in childhood or adolescence. Eruptive blue naevi (EBN) describes an abrupt appearance of clustered blue-grey naevi at various anatomical sites. Numbers of blue naevi have ranged from 3 to over 100.
What factors can lead to the development of EBN?
- Immunosuppression
- Medications including certain biologic or non-biologic immunosuppressants and chemotherapeutics (see: Drug-induced immunosuppression)
- Blistering disorders
- Cutaneous injuries
- Varicella zoster infection (see: Chickenpox or Shingles)
- Physiological: puberty and pregnancy
- Febrile illnesses
Describe the typical dermoscopic features of such lesions.
The typical findings on dermoscopy of a blue naevus are: structureless uniform blue pigmentation with a diffuse blue-white veil overlying the surface.
