Female, 27 years. Recurrent pigmentation after shave excision of naevus, skin of back.Show diagnosis & comments
Recurrent naevus (Ackerman pseudomelanoma)
- History of removal of banal naevus
- Interval usually weeks to months (in contrast to recurent melanoma: local recurrence usually after years)
- Scar tissue in upper dermis, with slightly enlarged and usually pigmented melanocytes, in compact nests
- Irregular distribution of similar pigmented naevoid melanocytes in overlying neoepidermis
- Very often an entirely banal looking naevus remnant in the pre-existent dermis bordering the scar
- Re-examination of histology of previously removed naevus, if available, is important to confirm the diagnosis
- Some of these benign lesions are macroscopically irregular and therefore suspicious: 'pseudomelanoma' of Ackerman.
Fox JC, Reed JA, Shea CR. The recurrent nevus phenomenon: a history of challenge, controversy, and discovery. Arch Pathol Lab Med. 2011 Jul;135(7):842-6.