Case Number : Case 1531 - 06 May Posted By: Guest

Not an easy one for me. I will wait for the next images but I considered morphea, scar tissue, I dont know how to make fit the localized acanthosis (associated acanthotic SK?) also the presence of numerous mast cells got my attention but I cannot make them fit

Very very difficult for me. " I dont know how to make fit the localized acantosis (associated acanthotic SK?) also the presence of numerous mast cells got my attention but I cannot make them fit"...Completely agree. is there any perineurial lymphoid infiltration ( fig bottom left and fig 3)? This could fit to a linear scleroderma scarring alopecia...

Just to share, I found this article http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3985512/ that remarks the role of mast cells and dermal scarring (something that I completely ignored) could they be related in this case? apparently they are related with scleroderma too http://www.ncbi.nlm.nih.gov/pubmed/1642658

I thought the pictures of the epidermis showed lichen simplex chronicus and the other pictures showed chronic inflammation with mast cells in the vicinity of a telogen follicle, apart from the picture of the scar, the site of which I cannot pinpoint on the low-power picture.  I, too, cannot tie things together. 

Agree with the difficulties above...scleroderma and LSC, both come to mind.

Best to wait for additional images!

Agree with the previous comments. Scleroderma, but having some problems when correlating with the epidermal findings.

Agree with the comments. Lichen simplex chronicus,  Dermal scar/morphoea. Scatterred mast cells and plasma cells. No definite suggestion of amyloid, but may do a Congo red. Waiting for the answer :)

So it is desmoplastic melanoma the mimicker of scars. Not easy to suspect in these images without the immunos. I think everybody had DM in the back of their heads due to the lymphoid aggregates and sclerotic dermis but in my mind it looked too paucicellular in the images to consider it as a differential... It would be nice to perform a SOX-10 too  

Great case! Thank's Dr Carr!

Scary....so easily missed!!

I forgot to thank Dr Chris Allen for kindly sharing this very tricky case.

Yes it is that terrible case where you forget to think of desmoplastic melanoma.  Thankfully the clinician had queried a melanocytic macule in the clinical information and an S100 was performed.  Can't remember if a CD34 was done but it really did not look like any neural tumour (lacking the delicate collagenous stroma). Also I did note a small focus of lentigo maligna in one follicle (not illustrated).

I have to be honest and had forgotten the case completely and I did not think of the diagnosis when perusing the case on Friday!  I was also thinking along the lines of morphoea.  Phillip McKee used to say at the beginning of each sign out say to your self "desmoplastic melanoma".  My advice have a very low threshold for doing an S100 on any scar-like or funny "myofibroblastic" spindle process especially when on the sun-damaged skin in the elderly.  Fortunately the lesions are fairly indolent and the metastatic rate for pure desmoplastic melanoma is low and it is more an issue of local control.  However a delay in correct diagnosis would obviously have potentially significant issues relating to the extent of surgery.