Pityriasis rubra pilaris
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Pityriasis rubra pilaris, abbreviated PRP, is an uncommon inflammatory skin disorder.
| Pityriasis rubra pilaris | |
|---|---|
| Diagnosis in short | |
|
| |
| LM | alterating orthokeratosis and parakeratosis (known as "checkerboard pattern"), marked uniform acanthosis with broad dermal papillae and broad epidermal ridges, , +/-eosinophils (common), follicular plugging, scattered foci of acantholysis (common), occasional mild spongiosis |
| LM DDx | fungal infection, psoriasis, Darier disease, seborrhoeic dermatitis |
| Stains | PASD -ve (to r/o fungal infections) |
| IF | negative (changes in Desmoglein 1 & Desmoglein 3 in pemphigus vulgaris) |
| Gross | salmon-coloured plaques, well-demarcated |
| Site | skin - see inflammatory skin disorders |
|
| |
| Associated Dx | HIV infection - recalcitrant PRP |
| Clinical history | Classic adult - self-limited exfoliative, erythematous dermatitis that starts over the head and neck and extends downwards forming orange plaques with spared islands of normal skin, follicular hyperkeratosis, palmar involvement with orange hyperkeratosis |
| Prevalence | uncommon |
| Treatment | retinoids, methotrexate and others |
General
- Uncommon.[1]
- Typically sporadic, may be familial.[2]
- Bimodal age distribution:[3]
- Children: <10 years.
- Adults: 40s and 50s.
Treatment:
- Retinoids, methotrexate and others.[3]
Gross
Microscopic
Features:[1]
- Alterating orthokeratosis and parakeratosis - known as "checkerboard pattern".
- Marked uniform acanthosis with broad dermal papillae and broad epidermal ridges.
- Follicular plugging.
- +/-Eosinophils (common).
- Scattered foci of acantholysis.[4]
- Occasional mild spongiosis.
Notes:
- PRP is easy to miss - clinical history (r/o PRP) usually needed to prompt correct diagnosis.
Microscopic DDx
- Psoriasis vulgaris[5] - thinned suprapapillary plates, hypogranulosis, neutrophils in the stratum corneum, dilated papillary dermal blood vessels, acantholysis absent.
- Lichen simplex chronicus - usually a localized process, not a widespread process.
- Darier disease - acantholysis is prominent with corps ronds and grains, follicular plugging absent.
- Pemphigus vulgaris - PRP with extensive acantholysis can mimic; IF will be negative in PRP.
- Hailey-Hailey disease - falling brick wall pattern of acantholysis.
- Seborrhoeic dermatitis - more spongiotic, often with neutrophils.
- Fungal infection.
Associated Diagnoses
- HIV infection - recalcitrant PRP.
Images
Stains
See also
References
- ↑ 1.0 1.1 Marrouche, N.; Kurban, M.; Kibbi, AG.; Abbas, O. (Apr 2014). "Pityriasis rubra pilaris: clinicopathological study of 32 cases from Lebanon.". Int J Dermatol 53 (4): 434-9. PMID 24783259.
- ↑ Mercer, JM.; Pushpanthan, C.; Anandakrishnan, C.; Landells, ID.. "Familial pityriasis rubra pilaris: case report and review.". J Cutan Med Surg 17 (4): 226-32. PMID 23815954.
- ↑ 3.0 3.1 3.2 Klein, A.; Landthaler, M.; Karrer, S. (2010). "Pityriasis rubra pilaris: a review of diagnosis and treatment.". Am J Clin Dermatol 11 (3): 157-70. doi:10.2165/11530070-000000000-00000. PMID 20184391.
- ↑ 4.0 4.1 4.2 Leger, M.; Newlove, T.; Robinson, M.; Patel, R.; Meehan, S.; Ramachandran, S. (Dec 2012). "Pityriasis rubra pilaris.". Dermatol Online J 18 (12): 14. PMID 23286804.
- ↑ Brinster, NK. (Mar 2008). "Dermatopathology for the surgical pathologist: a pattern based approach to the diagnosis of inflammatory skin disorders (part I).". Adv Anat Pathol 15 (2): 76-96. doi:10.1097/PAP.0b013e3181664e8d. PMID 18418089.