Case Number : Case 1414- 24 November Posted By: Guest

Even if p16 goes against it and the proliferation has clear spitzoid features I would still diagnose this as melanoma in situ.

Agree with [color=#1C2837][font=arial, verdana, tahoma, sans-serif][size=4]melanoma-in-situ. [/size][/font][/color]

Melanoma in situ with spitzoid features, the growth is mainly lentiginous with contiguous melanocytes and there is extensive pagetoid spread.

Agree with Melanoma in situ with spitzoid features. This is a fascinating field. Maybe this melanoma is not associated with CDKN2A mutation (considering that this is a case of familial melanoma), but other kind of germline mutation. CDKN2A mutations are now recognised as an important step in the progression of melanoma to the invasive growth. Spitzoid tumors may be associated with HRAS, ALK, BAP-1, BRAF and other oncogenes and tumor supressors, but little is said about in situ lesions. Most reported spitozid tumors we read are polypoid.

Agree with melanoma in situ.

Agree, I would report this as malignant melanoma in situ.
The main differential is a pagetoid Spitz, which typically shows single cell pattern of spread with intra-epidermal ascent, as also seen in this case. However, it is not a diagnosis that I am very comfortable making as the distinction from in situ lentiginous melanoma is difficult. According To Mckee's textbook, pagetoid Spitz is 'essentially a lesion seen in children and adolescents and if a similar lesion is seen in adults, a diagnosis of in situ melanoma is more appropriate'. Interested to know what others think about this entity.

Agreed and GREAT discussion. I called this melanoma in situ w spitzoid features.

This is a [b]small, atypical, intra-epidermal spitzoid lesion[/b] could be an evolving, or pagetoid Spitz, naevus but one cannot exclude MIS (I don't think one can make a diagnosis with confidence either way) - important point is completeness of excision and given history keep an eye on patient. I don't waste a lot of time worrying about the diagnosis of "SMALL DARK ATYPICAL INTRA-EPIDERMAL LESIONS" when the management / treatment is more important. Try to train your clinical colleagues never to take very narrow margins on small recently grown dark lesions (if they are not worried watch and wait, if they are concernced excision with 3mm of normal skin all the way round) - they are always close to impossible to classify microscopically and this becomes academic if margins are satisfactory!

Thanks for your comment, Richard.
But I guess, the problem is what defines a satisfactory margin! In our practice, if a lesion like this was excised by say a margin of 1-2mm, our clinicians would go back and do a further 5 mm excision if we were to call it melanoma in situ. If labelled pagetoid Spitz, they wouldn't do anything further. If the lesion is on a cosmetically sensitive site, I suppose the distinction does become important. Agree completely that histological distinction in such lesions is virtually impossible, so which way should one err towards??

Our clinicians won't go back to an in situ melanoma if it is excised histologically (after MDM discussion and aggreement of the team). Obviously what constitues a complete excision is down to discussion but certainly if there was a nice 2mm (on small atypical intra-epidermal lesions) I would be happy for watchful waiting in most instances (depending on lesion size degree of atypia etc. etc.). MelanA can be helpful to define the borders and you can also do levels. Far too many patient's get pointless re-excisions in my opinion. It emphasises my point to give it a slightly generous margin ab initio (i.e. train your team and don't spare their blushes for the patient's ultimate benefit).