Case 22 Female, 36 years. Pigmented papule, skin of lower legShow diagnosis & comments
Pigmented spindle cell naevus (Reed naevus), with relatively pronounced inflammatory response
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
Whether the inflammatory response is induced by pigment incontinence, or vice versa, is a moot point. In Reed naevi, both commonly occur together.