blue nevus (dermal melanocytoma)
Jump to navigation
Jump to search
Introduction
Variant of dermal nevus. An acquire firm, dark-blue to gray-black, nevus representing a local proliferation of dermal melanocytes.
Etiology
- ectopic accumulation of melanin-producing melanocytes in the dermis during migration from neural crest sites to the skin
Epidemiology
- onset in late adolescence
- equal sex distribution
Pathology
- melanin-containing fibroblast-like dermal melanocytes grouped in irregular bundles admixed with melanin-containing macrophages
- excessive fibrous tissue production in upper reticular dermis
- epidermis is normal
Clinical manifestations
- generally asymptomatic, of cosmetic concern
- appearance is gradual
- papules to nodules, generally < 1 cm in diameter
- color: blue, blue-gray, blue-black, occasionally with target-like pattern of pigmentation
- shape: generally round to oval
- firm to palpation
- most common on dorsal surface of hands or feet, but may occur at any site
Laboratory
- biopsy to rule out melanoma
Differential diagnosis
- dermatofibroma
- glomus tumor
- primary nodular or metastatic melanoma
- pigmented spindle cell (Spitz) nevus
- traumatic tattoo
- venous lakes (ectasias)
- cavernous hemangiomas
- Maffuci's syndrome
- blue rubber bleb syndrome
Management
- most nevi remain unchanges
- melanoma rarely arises from blue nevi
- indications for surgical excision & dermatopathology
- lesions > 1 cm
- sudden appearance of lesion
- change in lesion