Also known as speckled lentiginous naevus, zosteriform lentiginous naevus
What is naevus spilus?
Naevus spilus is a type of birthmark that consists of a flat brown background patch containing darker brown spots or tiny bumps.
What causes it?
Naevus spilus is caused by a localised defect in melanoblasts (the forerunners of pigment cells) that populate a particular area of the skin. There is some controversy as to whether naevus spilus represents a birthmark known as a variant of a congenital melanocytic naevus, or it is acquired later on in life.
What does it look like?
A variable number of black, brown or red-brown spots or tiny lumps are seen within a flat patch of tan-to-brown hyperpigmentation. The “background” tan patch is usually noted at birth, or soon after, while the spots within the patch appear over time.
Any site of the body might be affected.
The spots or bumps within the background stain are usually moles called pigmented naevi. There are many types of these including junctional, compound and intradermal naevi, Spitz and blue naevi.
There are reports of cutaneous melanoma arising within a naevus spilus but this is extremely rare.
How is naevus spilus diagnosed?
Diagnosis is by visual inspection. A skin biopsy will be needed if atypical features are present or there is a history of recent change.
How is naevus spilus treated?
Initially, naevus spilus should be photographed to document stability of the lesions. A biopsy will be needed for any suspicious areas.
Affected individuals should check the area as part of their regular full body self-examination and note any changes.
Laser treatment may be considered when the appearance of the naevus is of cosmetic concern. Both the Q-switched ruby and Q-switched Nd:YAG lasers have been used to treat the background hyperpigmentation and the speckles of naevus spilus. However, results are variable – some lesions respond well while others do not.
Regular self-examination is still necessary, even after successful treatment. You should seek medical advice for any unusual or new changes in appearance.
This information has been written by Dr Davin Lim and Dr Heba Jibreal
Updated 02 March 2016