In my very long personal clinical experience I have never seen coexistence of PLC and psoriasis. However PLC may sometimes look like psoriasis guttata and this would be possibly misinterpreted as an association or overlap. It is always possible that two different diseases could be present in the same subject but, before to conclude that PLC and psoriasis are present in the same individual, it is important to note that both could mimic the other.

Thank you Dr Jose.

I recently happened to see a young girl with diffuse invovement of scaly lesions ovr her legs, hands , chest and scalp. picture was very much similar to psoriasis, except that the scales were not typical of psoriasis. a bopsy revealed picture of PLC. hence i was in need of a clarification of coexistance or overlap.

Thank you for the clarification

From my experience of PLC notice that coexist with psoriasis, and have clinical and pathohistological evidence ,staying in the same patient. The must raise our question whether the clinical picture of PLC is a new variant of psoriasis guttata, or the opposite, the pathohistological picture of psoriasis guttate testifies for PLC.

I recently encountered a case of histopathologically proven PLC (more intense inflammation with marked necrotic keratinocytes similar to acute PL), but looks like psoriasis guttata clinically.

Thank you Dr Ko Ron Chen, and Dr Mybera Ferizi, for your inputs. I hope this discussion will open newer diagnostic criteria and also not to come to a blind clinical diagnosis of psoriasis.

Do the cclinical and therapeutc management vary for the two conditions or could they be treated as a single entity without burdening the patient.

In my experience of more than 30 years Of Dermatologic practice I never see psoriasis and PLC. Theoretically it is impossible to deny the hypothesis of co-existence but the hypothesis of existence of an overlap syndrome I think we could assume that it doesn't exist.

Dr. Americo Figereido’s experience together with my own represents roughly eight decades of dermatological practice. This would mean more than 160.000 patients (if we take an estimation of 2.000 yearly ); and our comments to your question are alike…. Of course in Medicine we must not say “never” or “always” But we can’t forget that clinical as well as pathological diagnosis is not like mathematics. Therefore Dr. Satyaprasad Venkata, you can take your own conclusions.

Hello Prof. Mascaro, dear friend, colleague and Master of a lot of spanish and portuguese dermatologists like ME. Thank you.

Dr Jose, We are new to this feild of dermatology. some cases which present like psoriasis when subjected to skin biopsy gives us a different picture suggesting pityrisis lichenoides chronica.

It is under these trying and difficult situatuions where the clinical picture is suggestive of one entity and a histopathological description of another entity would raise serious doubts in our mind, and hence this question was asked.

In medicine i do agree that medicine is not mathematics.

we have always grown up only with the guidance of our elders and will continue to do so.

In my opinion, PLC and Psoriasis are completely different entities. The etiopathogenesis and treatment are different for both (except maybe Phototherapy which can work for both). There is no overlap between the two. As some of the colleagues have already mentioned, some cases of PLC could be misdiagnosed as psoriasis; always look for Auspitz's sign and nail involvement which is seen only in psoriasis.

The pathology is quite different between these two and should not be misinterpreted by an experienced dermatolopathologist

This confusion do exist often in the early phase of psoriasis especially in guttate psoriasis. The clinical picture may suggest both. However a meticulous examination may help in differentiating both. As suggested earlier the pathogenesis is quite different in both conditions it is illogical of a coexistence. But in medicine we can not be dogmatic. Do follow up such cases and the time will tell you the diagnosis.

Prof Criton

Regarding the overlap of the psoriasis and pityriasis lichenoids clinically and pathologically, I agree that there is some clinical similarily but by careful clinical examination you can avoid this confusion between these two conditions . the pathology is quite different . coexistence of PLC and psoriasis Theoretically may exist.

Jorge L Sanchez

Add four additional decades of dermatological practice to those of drs Figaredo and Mascaro. The association of PLC and psoriasis is exteremely rare. Of course, early eruptive psorisis may be difficult to differentiate both ciinically and histopathologically from papules of PLC. Remember Brocq's quandary in his historical publication on

"Parapsoriasis".