Male, 51 years. Large, irregular flat hyperpigmentation, skin of shoulderShow diagnosis & comments
Lentiginous SAMPUS (so-called lentiginous naevoid melanoma), with dermal naevus remnant
LENTIGINOUS SAMPUS (SO-CALLED 'LENTIGINOUS MELANOMA', 'LENTIGINOUS NAEVOID MELANOMA')
- Manifests as an irregular, variably hyperpigmented patch that is macroscopically similar to lentigo maligna
- May arise in skin lacking substantial solar damage.
- Stable in size for prolonged periods, or slow growth
- Most cases coming to clinical attention are from middle-aged or elderly individuals
- Local recurrence after incomplete or narrow-margin excision may occur
- Occasional progression to invasive superficial spreading melanoma NOS have been mentioned.
- No distant metastases have so far been documented to arise from this lesion
- Since distant metastasis has not beeen documented so far, I prefer not to call these lesions (lentiginous) melanomas, despite the fact that this term has become entrenched in the literature.
In addition, many reported cases are entirely intraepidermal, which also makes the label of melanoma inappropriate.
Since these are very superficial lesions (entirely intraepidermal, or compound lesions with a very superficial component) and more data regarding their possible malignant potential are required, I prefer to use the term introduced by Dr David Elder:
SAMPUS (superficial atypical melanocytic proliferation of uncertain significance), lentiginous subtype.
Elder DE, Xu X. The approach to the patient with a difficult melanocytic lesion. Pathology. 2004 Oct;36(5):428-34.
King R. Lentiginous melanoma. Arch Pathol Lab Med. 2011 Mar;135(3):337-41.
Weedon D. Lentiginous melanoma. J Cutan Pathol. 2009 Nov;36(11):1232.
Mooi WJ. Lentiginous melanoma: melanoma subtype, or lentiginous SAMPUS? Adv Anat Pathol, in press.