Indian Dermatology Online Journal

: 2019  |  Volume : 10  |  Issue : 4  |  Page : 469--470

Koebner phenomenon in classic juvenile onset pityriasis rubra pilaris

Reena K Sharma1, Mudita Gupta1, Anchana Gulati2,  
1 Department of Dermatology, Venereology and Leprosy, IGMC, Shimla, Himachal Pradesh, India
2 Department of Pathology, Venereology and Leprosy, IGMC, Shimla, Himachal Pradesh, India

Correspondence Address:
Mudita Gupta
Departments of Dermatology, Venereology and Leprosy, I.G.M.C, Shimla, Himachal Pradesh

How to cite this article:
Sharma RK, Gupta M, Gulati A. Koebner phenomenon in classic juvenile onset pityriasis rubra pilaris.Indian Dermatol Online J 2019;10:469-470

How to cite this URL:
Sharma RK, Gupta M, Gulati A. Koebner phenomenon in classic juvenile onset pityriasis rubra pilaris. Indian Dermatol Online J [serial online] 2019 [cited 2020 Jun 3 ];10:469-470
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Full Text


A 6-year-old female child was brought with a 3-month history of mildly itchy scaly lesions all over the body with a cephalocaudal progression. There was no history of consanguinity or similar complaints in the family. On examination, there was generalized involvement of body with multiple discrete follicular and perifollicular papules and plaques covered with furfuraceous scales [Figure 1]. Linear streaks of these scaly papules were present on the trunk suggesting koebnerization [Figure 2]. There was mild palmoplantar keratoderma. The child was suspected to be having juvenile onset classical pityriasis rubra pilaris (PRP) with a differential of childhood-onset follicular psoriasis. Routine hematological and biochemical investigations were within normal limits. Histopathology showed orthokeratosis and parakeratosis in both vertical and horizontal directions with focal hypergranulosis, thick suprapapillary plates, broad rete ridges, and sparse superficial perivascular infiltration [Figure 3]a. In addition, follicular plugging and shoulder parakeratosis were seen [Figure 3]b. The final diagnosis of juvenile onset classical PRP with koebnerization was made. The child was started on isotretinoin 10 mg/day, with a slight improvement seen after 2 months of follow up.{Figure 1}{Figure 2}{Figure 3}

PRP is an inflammatory papulosquamous dermatosis initially thought to be a variant of psoriasis. In addition to trauma, PRP has also been reported in association with burns, malignancies, vaccinations, agammaglobulinemia, and arthropathy. It is classified depending on the age of onset, behavior, distribution, and prognosis of disease; three of these are juvenile variants classical (type III), circumscribed (type IV), and atypical (type V). Juvenile classical (type III) PRP presents between 5 and 10 years with the cephalocaudal progression of follicular and perifollicular erythematous papules, which coalesce to form plaques studded with spiny hyperkeratosis. Areas of sparing and palmoplantar keratoderma with an orange hue may be seen. Our patient had a classical progression and morphology of lesions as seen in PRP type III. But there was only mild palmoplantar keratoderma with no islands of sparing. Childhood-onset follicular psoriasis also may have similar morphology and distribution of lesions with involvement of palms and soles, but the cephalocaudal progression is not a feature.

Histopathology in follicular psoriasis shows follicular plugging with infundibular dilatation and parakeratotic ostium with loss of a granular layer and the presence of neutrophilic infiltrate.[1] The presence of vertical and horizontal orthokeratosis and parakeratosis with focal hypergranulosis and thickening of the suprapapillary plate with the lack of significant perivascular neutrophilic infiltrate suggested PRP in our patient.

The Koebner phenomenon (KP) is characterized by the development of lesions of the same morphology and histopathology as the primary cutaneous disease at the traumatized uninvolved skin. Boyd and Neldner divided KP into four types: (1) true KP; (2) pseudo KP, seen because of autoinoculation in infectious disease; (3) occasionally occurring KP, which is not reproducible. In this category, disease occasionally localizes to the sites of trauma. (4) Questionable isomorphic phenomenon, where only a single case report is described.[2] In PRP, an isomorphic response has been described very rarely.[3]

Epidermal hyperplasia in psoriasis is driven by interleukin (IL)-23 and mediated by IL-17 and IL-22.[4] IL-17 has been found to be increased in lesions of PRP and targeted therapy against this immune mediator has shown improvement in resistant PRP.[5] In spite of being two different types of papulosquamous diseases, PRP shares certain clinical, histopathological, and immunological features with psoriasis.[4] KP in psoriasis occurs because of the increased expression of Toll-like receptor 9 and activation of Th-17. A similar mechanism may be involved in koebnerization in PRP. We are reporting a case of juvenile PRP with koebnerization explaining the possible link between the pathogenesis of KP in PRP with psoriasis.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

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