Case 44 Male, 13 years. Pigmented papule, skin of armShow diagnosis & comments
- Two components: most commonly a combination of compound naevus and deep penetrating naevus
- Each of the two components shows the classical features of the corresponding naevus subtype
- The presence of two divergent naevus histological phemotypes may inappropriately raise a suspicion of malignancy (malignant transformation within a naevus)
- The blue naevus-part of the lesion may be noticed clinically and raise suspicion (variation in colour of the lesion; asymmetry)
- The blue naevus component is most often located in the central part, but it may be on one side, resulting in gross asymmetry
- Since each of the two component can be recognized as a benign naevus, the combined lesion is benign as well
- The lesion is sometimes whimsically referred to as 'true and blue naevus'
- A very minor blue naevus-component is not rare in other naevus types, and a small 'non-blue' component is regularly encountered in blue naevi, so that the phenomenon of combined naevus subtypes is not rare at al. The term 'combined naevus' is better reserved for those lesions where both components constitute a significant part of the entire lesion.