Congenital melanocytic nevus admixed with speckled lentiginous nevus.

Sir,

Speckled lentiginous nevus (SLN) clinically presents as a circumscribed patch of hyperpigmentation that has features consistent with lentigines or café-au-lait macules, including scattered, more darkly-pigmented macular, and papular elements.[1] In some cases, dark spots from lentigines to compound or intradermal nevi may occur, and various types of nevi (blue nevi, Spitz nevi) may be present in the same lesion.2 However, only a few cases of the presence of an SLN and concurrent congenital melanocytic nevus (CMN) since birth have been reported.34

A 28-year-old male presented with a large pigmented lesion on his back, present since birth. This congenital lesion consisted of a 7 × 8 cm black hairy plaque on a large light brown patch with numerous scattered darker brown macules [Figure 1]. Its increase in size was solely in proportion to the patient's growth. The patient had no other skin abnormality, underlying disease, or family history. A biopsy was obtained from the black plaque on his back.

Figure 1

A tannish-brown hyper pigmentation with superimposed dark macules, and black hairly plaques ranging up to 7 × 8 cm on the back

Histopathological examination of the specimen showed basal hyperpigmentation with a lentiginous pattern and nevus cells penetrating the dermis around hair follicles. There was no cytological or architectural atypia within the lesion [Figures 2a and b].

Figure 2

Basal hyperpigmentation with rete ridge elongation and nevus cell within the reticular dermis ((a) H and E, ×100, (b) H and E, ×200)

A CMN usually has a somewhat speckled component because of an uneven melanocytic distribution. In such cases, the speckled component is frequently seen only at the peripheral portion of the nevus.23 Therefore, the speckled component of the CMN can be distinguished from an SLN clinically. The speckled component in our patient did not exhibit a peripheral distribution, and there was a classic CMN admixed with a speckled component at the centre of the lesion. A lentiginous pattern of rete ridges in CMN is uncommon. Therefore, CMN seems to have simultaneously occurred above the base of the SLN rather than the SLN spreading from the CMN. Moreover, the SLN and CMN had been present concurrently since birth. Therefore, we diagnosed CMN with concurrent SLN. A few cases of CMN hybrid with SLN have been reported previously. These reports emphasised that SLN that fall within the spectrum of CMN include the following observations. First, SLN present at birth or are noted soon thereafter. Second, the patterns of distribution reflect embryonic development. Third, SLN exhibit hamartomatous behaviour with various types of nevi (e.g. blue nevi, Spitz nevi, and junctional nevi) presenting within the same lesion over time.2–4 We described a patient with a congenital pigmented lesion that had the clinical appearance of an SLN, and presented as a hybrid lesion with a CMN. The occurrence of CMN with SLN is rare. We believe that this case supports the hypothesis that SLN is a subtype of CMN.