Pigmented Spindle Cell Nevus Of Reed

Epidemiology:

• F > M
• 20s median age

Common sites:

• extremities
• trunk
• rarely head and neck (unlike Spitz)

Gross features:

• small (<1cm)
• solitary
• deeply pigmented
• well-circumscribed
• maculopapule

Histologic features:

• symmetry
• maturation
• nests and fascicles of spindle melanocytes arrayed parallel to epidermis within dermal-epidermal junction and dermal papillae
• (junctional and compound varieties exclusively)
• usually no deeper than superficial reticular dermis
• form a confluent plaque of tumour growth
• expansile pattern of growth (rather than infiltrative pattern in Spitz)
• monomorphous nuclei
• nucleus closely resembles nearby keratinocyte nuclei
• larger and more open than junctional cells of common melanocytic nevi
• one or more prominent small nucleoli
• abundant melanin pigment in cells (contrast to Spitz)
• single-cell infiltration of epidermis maybe present
• dense melanophages often
• lymphocytic response at base in some
• mitoses uncommon

Immunophenotype:

Marker:

Sensitivity:

Specificity:

Molecular features:

Other features:

• benign
• frequently misdiagnosed clinically as superficial spreading melanoma

References:

• Sternberg 2004