Case Number : Case 2532 - 20 March 2020 Posted By: Dr. Richard Carr

The alternate para and ortokeratosis with atypical interadnexal keratinocytes and the poorly attenuated rete ridge, with lentiginous growth of atypical melanocytes and prominent adnexal involvement, make me think of a lentigo maligna arisen in a actinic keratosis/solar lentigo.  

25 minutes ago, vincenzo said:

The alternate para and ortokeratosis with atypical interadnexal keratinocytes and the poorly attenuated rete ridge, with lentiginous growth of atypical melanocytes and prominent adnexal involvement, make me think of a lentigo maligna arisen in a actinic keratosis/solar lentigo.  

Agree

18 hours ago, vincenzo said:

The alternate para and ortokeratosis with atypical interadnexal keratinocytes and the poorly attenuated rete ridge, with lentiginous growth of atypical melanocytes and prominent adnexal involvement, make me think of a lentigo maligna arisen in a actinic keratosis/solar lentigo.  

Agree.

S100?

lentigo maligna.

if you have this kind of melanocytic confluence with a few asymmetrical nests, over sun exposed skin and elderly patient, it should be called Lentigo Maligna, with or without IHC. In this case with AK associated. Agree with Vincenzo. Nice case, thanks for sharing.

Thank you for your responses but on this occasion I beg to differ.

My report: Actinic keratosis, pigmented, with hyperplasia of enlarged dendritic melanocytes of doubtful clinical significance.

Discussion: No confluence and this sort of dendritic melanocytic hyperplasia can be seen in seborrhoeic keratosis, pigmented bowen's, BCC, melanocytic matricoma etc. etc. I'd be very wary about diagnosing lentigo maligna in the setting of pigmented actinic keratosis without more firm evidence. Of course I may be wrong hence my "..of doubtful clinical significance".

Please stay safe during these challenging times (Covid 19).

Thanks, Richard.