Case 48B Male, 15 years. Papule, skin of back, with central hyperpigmentation (same case as Case 48A): HMB-45 immune stainShow diagnosis & comments
Combined naevus with deep penetrating naevus-component.
HMB-45 positivity in the pigmentproducing deep penetrating naevus component, not in flanking dermal part of the naevus NOS-component.
HMB-45 is a monoclonal antibody binding to an oligosaccharide side chain of a glycoconjugate present in immature melanosomes. It is therefore logical that it stains parts of a naevus that is involved in melanin pigment production.