Diagnosis:

Pigmented spindle cell naevus, congenital (in view of patietnt history)

Comments:

PIGMENTED SPINDLE CELL NAEVUS (REED NAEVUS)

• Spitz naevus variant occurring predominantly in children, adolescents and young adults
• Usually compact and densely cellular lesion
• Large spindle cells, often containing much melanin pigment, but some examples are poorly pigmented
• Junctional component forms nests, often confluent, resulting in irregular masses
• Reactive epidermal hyperplasia
• Transepidermal elimination of nests is common
• Ascent of solitary cells is commonly present
• Mitotic activity is commonly identified. Abnormal mitotic figures are not a feature.
• Dermal component is commonly rather cellular and compact, but there is no deep extenstion into the dermis.
• Often melanophages and round-cell inflammatory infiltrate
• Overall, this densely cellular lesion has a regular appearance, devoid of sudden changes in cell type, architecture or reactive epidermal or dermal changes