Both unilateral naevus achromicus and congenital agminated Spitz naevi in a checkerboard mosaic pattern.

Abstract

Sir, Spitz naevus is considered to be a type of melanocytic naevus. The solitary form is the most frequent, while multiple disseminated and multiple agminated types are considered rare. Multiple Spitz naevi disseminated over the entire surface, grouped and arizing on normal skin, hypopigmented or hyperpigmented area have been described.1–2 The only case in which Spitz naevi arose on a depigmented patch of naevus achromicus was described by Korting et al.3 Naevus achromicus (NA) is a congenital, non‐progressive, hypopigmented macule or patch that may be localized, segmental or, more rarely, systematized when it follows Blaschko’s lines.4 Very rarely, it has been described in association with other skin lesions or with lesions located within it.5 Here we describe a patient in whom multiple agminated congenital Spitz naevi arose on a large unilateral achromic patch disposed in a particular distribution, similar to that which Happle defined as a checkerboard mosaic pattern. A 4‐year‐old female child had a congenital pink papule (4‐mm in diameter) located on her left forearm and present from birth. From the fourth month of life several similar papular lesions, 1–4 mm in diameter, erupted. The lesions were pink and light or dark brown in colour, and smooth or slightly rough on the surface. All these lesions were confined within the distribution of a large unilateral congenital achromic area covering the back from midline at the level of T5–T6 extending laterally onto the right shoulder and arm down to the hand (Fig. 1a). In the thorax area, the achromic lesion involved a wide region from the midline at the level of T5–T6 extending on the flexural aspect of the right arm, forearm and hand (Fig. 1b). Some older papular lesions had become modified in their colour and flattened. Physical examination at the age of 4 years revealed about 200 brown and reddish papular lesions. Three biopsies were performed. In every case, histological examination showed the features of Spitz naevus. The young patient was in good health and had no family history of similar lesions. Routine blood count and bone radiography of the upper extremities were normal.