What does the development of an exophytic nodule on this naevus in the child patient, that has been present since birth, usually represent? Does the patched-hedgehog signalling pathway malfunction in this regard? What advice would you give the parent?
sebaceous glands, which are often located abnormally high in the
dermis, with an increased number of closely set lobules and
A variety of appendageal tumours, sometimes
multiple, may develop within sebaceous naevi. The most commonly
reported are trichoblastoma and syringocystadenoma papilliferum
that are seen in as many as half of all cases of naevus sebaceous
are not always easily differentiated from basal cell carcinoma
(BCC). Misinterpretation of trichoblastoma and basaloid
proliferation as BCC has caused problems in the past.
Short and long answers are provided below as comments.