Case Number : Case 1872 - 1 August - Dr Iskander Chaudhry (Invited) Posted By: Guest

Im on my phone but excuses appart I thought this case could be compatible with a proliferative nodule on a nevus, due to sharp circumscription, homogeneous distribution of pigment and minimal spitzoid like atypia. PN in acquired nevi are infrequent but reported. In real life I would perform some immunos (ki67, melan A, HMB-45 and bleaching) and probably show the case to someone else as the clinical picture is rather alarming.

have never seen one before, wonder if a pigmented melanocytoma would be a valid differential on morphology.

I’m on my iPhone, too, and don’t remember if lip could be a usual site for PEM , but there are many typical large and macro nucleolated cells between the heavily pigmented ones. So Pigmented Epithelioid MelanocytomaI is my favorite spot. 

PS just seen the Urmilapandey comment so am glad we are thinking about the same diagnosis. 

First impression, pigmented epithelioid melanocytoma too. 

Massi and LeBoit, on their absolutely necessary textbook Histological Diagnosis of Nevi and Melanoma, classify melanocytoma as a benign lesion in three circumstances:

• melanocytoma in the setting of Carney complex;
• combined melanocytoma; and
• melanocytoma with maturation in blue nevus, Spitz nevus, or other forms of nevus.

The present lesion has microscopic features of benignity, including small size, confinement to the superficial dermis, sharp circumscription, and insignificant mitotic activity. On the other hand, I don't think it can be accommodate in any of the above three scenarios, and I feel particularly concerned facing a melanocytic tumor that arose from a pre-existing nevus (there seems to be a junctional nevus on the left side of the two first images, and the case history report a nodular change on a longstanding pigmented lesion) on a sun-exposed site of a woman on her late sixties. So I'd consider this lesion as a low-grade malignant melanocytoma with metastatic capability to regional lymph nodes.

6 minutes ago, Robledo F. Rocha said:

Massi and LeBoit, on their absolutely necessary textbook Histological Diagnosis of Nevi and Melanoma, classify melanocytoma as a benign lesion in three circumstances:

• melanocytoma in the setting of Carney complex;
• combined melanocytoma; and
• melanocytoma with maturation in blue nevus, Spitz nevus, or other forms of nevus.

The present lesion has microscopic features of benignity, including small size, confinement to the superficial dermis, sharp circumscription, and insignificant mitotic activity. On the other hand, I don't think it can be accommodate in any of the above three scenarios, and I feel particularly concerned facing a melanocytic tumor that arose from a pre-existing nevus (there seems to be a junctional nevus on the left side of the two first images, and the case history report a nodular change on a longstanding pigmented lesion) on a sun-exposed site of a woman on her late sixties. So I'd consider this lesion as a low-grade malignant melanocytoma with metastatic capability to regional lymph nodes.

thanks for the information Robeldo

Dear All 

Dr Chaudhry added 3 more insitu images 

DermpathPRO Admin

Like it less now, it looks like melanoma in situ with important elastosis and areas suspicious for regression. 

So agree that this should be up-graded, I was mistaken before.

Don't really like it due to some of the reasons cited by Robledo. There is a junctional run of cells, a nodule with abnormal pigment network, possible fine scarring in the last image and atypia. Going for a melanoma. Would have looked at a bleached section, Mel-A and Ki67 .

Dear All 

Thank you for your comments. I have now had a few of these cases and call them 'pigment synthesising' melanomas after the name suggested by Eduardo et al. The proliferation index is often low but I have found clinicians manage them in the same way as conventional melanomas. Is this the experience of others ? 

This lesion has a worry atypical in situ component which you don't always see

Best Regards

Iskander 

Agree with you Iskander. I expect a low risk for metastasis of this "well differentiated" indolent appearing melanoma but obviously hard to predict.

Age, sun damaged skin (FACE!) the junctional component seems to trickle to the edge, in addition some dermal atypia: melanoma. But would like to see melanA (red) to evaluate better: symmetry, delimitation and pagetoid spread