Superficial spreading melanoma and blue naevus within naevus spilus--ultrastructural assessment of giant pigment granules.
BACKGROUND
Abnormal melanosomes occur in naevus spilus (NS).


OBJECTIVE
To determine whether melanoma arising in NS contains abnormal melanosomes.


METHODS
Light and electron microscopy of melanoma within NS and congenital naevus (Case 1), and of blue naevus within NS (Case 2). Light microscopy of additional naevi and melanomas.


RESULTS
The melanoma and NS (Case 1) both had large numbers of giant pigment granules (GPGs), demonstrated ultrastructurally to be melanosome macrocomplexes. These were not observed in a congenital naevus (Case 1), or in the blue naevus within NS (Case 2). Small numbers of GPGs were observed in 0/2 NS, 8/16 benign naevi and 11/16 malignant melanomas (MMs).


CONCLUSIONS
NS may be associated with other melanocytic tumours including MM and blue naevi; abnormal melanosomes in NS may also be present in the associated tumour. The prognostic importance of these is unknown, but occasional GPGs in melanocytic lesions are a frequent finding.
Cox
N H
NH
Department of Dermatology, Cumberland Infirmary, Carlisle, UK.
Malcolm
A
A
Long
E D
ED
D000328:Adult; D003594:Cytoplasmic Granules / Q000648:ultrastructure*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008543:Melanins; D008544:Melanocytes / Q000648:ultrastructure; D008545:Melanoma / Q000648:ultrastructure*; D008854:Microscopy, Electron; D009378:Neoplasms, Multiple Primary / Q000648:ultrastructure*; D018329:Nevus, Blue / Q000648:ultrastructure*; D009508:Nevus, Pigmented / Q000151:congenital / Q000648:ultrastructure*; D011379:Prognosis; D012878:Skin Neoplasms / Q000151:congenital / Q000648:ultrastructure*
D008543:Melanins