Case Number : Case 748 - 29 Apr Posted By: Guest

Lichen simplex

pagetoid reticulosis?

I can see marked orthokeratosis with focal parakeratosis on the right side. The 3rd and 4th images illustrates with certainty an interface reaction with necrotic keratinocytes along the basal cell layer and above it. There is marked solar elastosis. The lesion is single as appears from the clinical description. I am thinking of the rare creeping form of LPLK, which shows only focal acute activity. Although lichen simplex may explain the apparently thickened collagen in the dermal papillae and the marked orthokeratosis but it does not explain the interface dermatitis seen focally. I think itching can cause some scattered necrotic keratinocytes but not as this peculiar pattern seen here along the DEJ associated with interface lymphocytes. Nice case...

Please take a look at the extra immuno images on last Friday's case (747) that the Dermpath team posted for me. Shows how helpful immuno can be at times!

[size=4][font=arial, helvetica, sans-serif]Looks to me like three processes:
1.[i] Lichen simplex chronicus[/i]: [color=#000080]Primary findings are psoriasiform hyperplasia with hyperorthokeratosis, wedge-shaped hypergranulosis, stratum lucidum, and mixed acral type basophilic compact hyperorthokeratosis and parakeratosis, with mild acanthosis of a terminal hair infundibulum. Rare necrotic keratinocytes and sparse spongiosis are expected.[/color]
2. [i]Chronic inflammatory reaction[/i]: [color=#000080] Mixture of solitary, small lymphocyte-like hyperchromatic cells and larger mononuclear cells with nucleoli and open nuclei, some with perinuclear halos, with patchy asymmetric distribution in epidermis and papillary dermis. There is predominantly low level pagetoid scatter, with occasional elimination into the stratum corneum. This looks like a classic inflammatory reaction pattern in LSC, to me. Pagetoid reticulosis would be a DDx consideration, (as it often presents with psoriasiform architecture), but the mixed cytology and low density patchy infiltrate doesn't make it for me. Stains for CD4 and CD8 (should be CD4+ in most cases), and CD1a for Langerhans' cells might clear up the identity of the intraepidermal infiltrate if there is doubt. [/color]
3. [i]Marked solar elastosis[/i].[/font][/size]

I suspect for LSC. In Pagetoid reticulosos (PG) i wolud expect more epidermotropism. I also think we would expect lots of CD30 cells.

Thanks for everyone who contributed, the diagnosis is lichen simplex chronicus.