Case Number : Case 2966 - 18 November 2021 Posted By: Saleem Taibjee

Pseudoxanthoma elasticum (PXE) and PXE- like papillary dermal elastolysis are the main differentials here. Clinicopathological correlation after staining for elastic fibres and von Kossa stain to detect  calcification of degraded elastic fibres will help in arrival at the diagnosis. 

Would consider PXE-like papillary dermal elastolysis or white fibrous papulosis of neck- both related disorders. Elastic stains and CPC needed. 

I think there are no melanocytes in epidermis. First, I would like to perform SOX10. 

I thought of LSA with evidence of actinic damage, but widespread LSA is rare, 

new thing i learnt

I agree with Anil and Meenakshi.  I think this is PXE-like papillary dermal elastolysis.  The gender and age of the patient are typical.

Without clinical features my first spot had been TMEP mastocytosis, but…waiting for final answer. 

I agree with possible TMEP. Need IHC

51 minutes ago, daniellindsay said:

I agree with possible TMEP. Need IHC

TMEP doesn't fit with the clinical details.

I was being a bit deceitful. I did not mention that the clinician queried vitiligo versus lichen sclerosus. 

As Cem astutely points out, there are no melanocytes in the basal layer. This is further confirmed by Melan-A (see below). Hence I did think this is very likely to be vitiligo, another case we can add to the differential diagnosis of 'invisible dermatoses'. Of course, this is usually a clinical diagnosis and rarely biopsied.

I have checked back on the slide, and I do feel that the elastic is within normal limits in this case. So I don't think this is PXE-like papillary dermal elastolysis or other disorder of elastic fibres (although good suggestions), and similarly I cannot see any increase in mast cells.

BW
Saleem

I accept the loss of melanocytes, but how do you explain the "slight atrophy"?

I can't readily explain the atrophy noted clinically. But I am not really seeing any histological counterpart (the epidermis looks of normal thickness). I suppose topical steroid could be a factor if a history of prolonged usage. I think it may be a red herring.